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MC How-To
Step by step: From general maintenance to complete restorations, we share tips and tricks for working on classic bikes.

1968 Triumph Bonneville Voltage Regulator Upgrade

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Making sure your charging system is working to full capacity is important on a number of fronts. To begin with, there's the simple issue of generating enough voltage to keep your lights bright. This is particularly important on vintage bikes, which generally have low-capacity charging systems and run low-output headlights, which tend to be dim even with full voltage. And even if your lights are off, there's the issue of generating enough voltage for proper ignition. If you own a decades-old British twin, chances are good you've already ditched the stock ignition points for electronic ignition, a highly recommended upgrade to ensure steady, reliable firing of the spark plugs. However, some electronic ignitions are very sensitive to voltage supply, dropping completely out of circuit if the voltage drops below a certain range. Boyer electronic ignitions, for example, will drop out below 10 volts.

On Sixties and Seventies British bikes, the original Lucas charging system can be prone to failure. By the mid-Sixties, most British motorcycles were using Lucas charging systems with Lucas' silicone diode rectifier for AC to DC voltage conversion and a Lucas zener diode for voltage regulation. Although relatively simple components, after 40-50 years of vibration and exposure, the voltage regulator and rectifier are ripe for replacement. The original-style components are still readily available, but there are better products on the market that deliver superior performance and reliability, like the Podtronics voltage regulator/rectifier we recently installed on Tech Q&A man Keith Fellenstein's 1968 Triumph T120R Bonneville.

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Keith's Bonneville didn't have any particular charging issues, but with a fresh Pazon electronic ignition upgrade, and wanting also to convert to 12-volt negative ground from positive ground, Keith considered it a good move. Adding to the appeal, it's also a relatively cheap and easy conversion. The Podtronics unit was $57 (before shipping), and while we did opt to clip off what became redundant ground lines from the old rectifier to the battery and frame, had we wanted to, we didn't have to make any permanent changes to the original wiring. Keith's bike already had a replacement wiring harness, so we didn't feel bad about altering it in any way as it's not original.

We also like this upgrade because A) it delivers superior performance over stock and B) the only way anyone will know the charging system has been changed is if they lift the seat and see the new Podtronics unit in place of the original Lucas silicone rectifier. On 1968 and up through the mid-Seventies Triumphs the Lucas regulator (the zener diode) is housed in a large, finned aluminum heat sink attached to the bottom of the lower fork yoke. You can leave it in place to preserve your bike's original looks, as we did, or remove it. For the conversion, we isolated the wiring to the zener diode and then tucked it into the headlamp shell.

We also switched the Bonneville's electrical system from 12-volt positive to 12-volt negative ground. The Podtronics will work either way, as will the Pazon electronic ignition. Switching from positive to negative ground is easy, requiring no permanent changes. Finally, we upgraded to an LED headlamp and taillight. The taillight was a Sylvania Zevo 2357R red LED ($24.95 at O'Reilly Auto Parts). We got our H4-style headlight shell ($44.95) and 80-watt LED bulb ($59.95) from Donelson Cycle. You'll also need an H4 headlamp socket and pigtail ($3-$5 at O'Reilly). The lights are much brighter and with a significantly reduced amperage draw, and they'll basically last forever.

As ever, we recommend having a good shop manual on hand for parts identification and proper torque specs.

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1) Disconnect the positive lead to the battery, followed by the negative lead. The stock silicone diode rectifier is located behind the battery box. Remove the nut securing the rectifier. Remove the rectifier and disconnect the electrical leads.

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2) The zener diode, which regulates charging voltage, is housed in a large heat sink located on the lower fork yoke. We left it in place to preserve our bike's original look, but it must be taken out of circuit. Remove the ground strap from the bottom of the heat sink, then resecure the heat sink to its mount.

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3) Next, reach behind the heat sink and unplug the brown/white lead running to the zener diode.

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4) We left the wiring to the zener diode in place, isolating it from the system by sealing it in heat-shrink tubing.

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5) Next, we routed the now isolated wires into the headlamp bucket to keep them out of the way.

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6) We also converted our Triumph from positive ground to negative ground, which required swapping the blue/brown and brown/white leads to the ammeter in the headlamp housing, shown here as they were positioned originally, with the brown/white lead already disconnected.

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7) Next, we mounted the new Podtronics regulator/rectifier, securing it with a single bolt to the same locating point as the original rectifier.

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8) We then connected the black lead from the Podtronics to the red ground lead from the wiring loom that previously ran to the ground post on the stock rectifier, wrapping the red lead with black heat shrink tubing to color code it as negative ground after first removing the now unneeded extra red leads that ran from the rectifier to the frame and battery.

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9) Next, we connected the brown/white lead (which we marked with a "+" for positive) previously disconnected from the stock rectifier to the red lead to the Podtronics unit.

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10) Connect the green/white and green/yellow alternator leads that ran to the Lucas rectifier to the yellow leads to the Podtronics unit. The alternator output is AC so it doesn't matter which alternator lead goes to which yellow lead to the Podtronics.

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11) We installed a 15-amp blade-type fuse to the blue/brown power lead from the wiring loom after covering the blue/brown lead with red heat shrink tubing. The eyelet will run to the positive side of the battery.

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12) Here's the battery back in place, with the now red fused power lead running to the positive side of the battery and the formerly red but now black-sheathed ground leads running to the negative side of the battery.

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13) Our Triumph was already running a Pazon electronic ignition. The Pazon will work with either negative or positive ground. With the conversion, the red and white leads had to be swapped.

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14) As wired for positive ground, the red lead from the Pazon ran to the "+" side of the left ignition coil and the white lead ran to switched power. The red lead running rearward from the coil goes to ground.

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15) With the conversion to negative ground, switched power connects to the "+" side of the left coil. The red lead running to ground connects to the white lead to the Pazon.

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16) We replaced the stock headlamp and taillight with LED bulbs. For the headlamp, that meant getting a complete shell compatible with H4-type halogen bulbs, but fitting it with an LED bulb. The replacement headlamp is on the left, the stock to the right.

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17) For the taillight we used a Sylvania Zevo 2357R red LED bulb, which directs the light to the reflector. Like the LED headlamp, it's brighter and uses less power than the standard incandescent bulb, and should last basically forever.

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18) The ammeter gauge tells the tale, the current draw with lights on dropping from 4 amps-plus (top) to less than 2 amps (above).

Having a Blast Using our TP Tools Skat Cat 40 Blast Cabinet

Before and after: The Laverda SF2 fork yokes were pretty rough, but after media blasting they’re ready for fresh paint. Photos by Richard Backus.

We’ve wanted a good media blast cabinet for, oh, like forever, so actually having one makes us almost giggle every time we find an excuse to put it to work. We picked up our TP Tools Skat Cat 40 blast cabinet about a year ago, and since then it’s become a central piece of equipment in the Motorcycle Classics garage, an alchemist's dream that lets you magically turn lead into gold by transforming time-worn parts into like new forms, ready for refinishing. Just recently, we blasted our way through a trio of steering bits; two motorcycle related and one bicycle.

First up was the upper fork yoke on my daughter’s 1980 Moto Guzzi V50. The original plan was to replace the Guzzi’s pitted fork tubes and leaking fork seals. The upper yoke had to come off to pull the tubes, and it seemed pointless to put it back on with its scruffy and worn black paint. Guzzi seems to have gone back and forth on yoke finish at the time, sometimes painting them black and others leaving them in a natural aluminum finish. On the V50, the bottom yoke was a natural aluminum finish and the top was black, so I opted to take the top yoke back to a natural finish.

Previously, I would have used a chemical stripper to remove the original paint. That works OK, but it’s slow and tedious compared to having a blast cabinet, and there’s a fair bit of clean up and final prep to get to a finished result. Using the TP Tools blast cabinet, it took maybe five minutes tops to completely strip the yoke. Once stripped, I worked it over with a buffing wheel, starting with Brown Tripoli compound before moving to White Rouge. That took longer than stripping the yoke, and maybe even a little longer than had I opted to repaint it, but the result is a clean, natural aluminum finish, and it looks excellent back on the bike.

The Moto Guzzi V50 fork yoke before blasting.

The Moto Guzzi V50 fork yoke midway through blasting.


The Moto Guzzi V50 fork yoke blasted and polished.

Next up was refinishing the ugly off-white handlebar stem on my road bike. The stem was a freebie from a friend, but I wanted a natural finish and was actually on the cusp of getting a new one when I did the Guzzi. I went through the same process as with the Guzzi’s steering yoke, and like the Guzzi, it only took a few minutes to strip. And being a smaller piece, it was a pretty quick job to polish it up. I didn’t go for a mirror finish, but could have if I’d wanted to put in a little more effort.


The painted bicycle stem.


The bicycle stem after blasting.


The bicycle stem after polishing.

That was hardly done when I turned my attention to replacing the steering head bearings on a 1974 Laverda SF2 750. Pulling the yokes off, the paint on the upper yoke was much worse than on the Guzzi, and the lower was no better. Unlike Moto Guzzi, Laverda was consistent with the final finish on the yokes, painting all of them something between a flat to satin black. The paint on the Laverda yokes was thicker than on the Guzzi, so it took a little longer to strip them, taking maybe 10 minutes each to get them how I wanted them. I took both pieces to get powder coated, but haven’t collected them yet. I’ll post picks of the finished yokes shortly.

A quick note on blast media:
We started with TP Tools’ suggested blast media, Skat Magic Abrasive crushed glass. That gave excellent results on aluminum, which is what we’re mostly working with, leaving a perfect base finish ready for primer and paint. When it was time to restock media, we turned to our local Tractor Supply Co. store, where we picked up a 50-pound plastic drum of their house brand U.S. Minerals crushed glass media. Both are rated as medium grit, and both work well, although we think the TP product performs better and lasts longer, and with less dust, which is a downside to crushed glass versus glass beads. The upside? Crushed glass cuts faster. The price was nominally the same, the Skat Magic priced at $31/50 pounds and the TSC glass media priced at $33.99/50 pounds. We’d go back to the Skat Magic if we could, but shipping costs pretty much kill that option for us. Next time around, we’ll stock up with glass beads to see how that media performs relative to the crushed glass. And finally, we’ll also order another air filter for our Skat Blast HEPA Vacuum ($27.95 for a standard filter, $42.95 for HEPA). We’re on our second so far, and we’ll be curious to see if we get longer filter life with glass beads, as the filter seems to load up quicker than we’d expect given our blast cabinet’s relatively light work load. — Richard Backus

Honda CB450 Starter Overhaul

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As reliable as vintage Japanese electrical hardware may be, everything has a service life, and that includes the starter motor on our subject 1970 Honda CB450K4, which had been displaying a tendency to drag and otherwise turn slowly making the CB450 somewhat hard to start.

BikeMasterNew starters for the CB450 haven’t been available for some time, and while used starters are — typically for around $50- $90 — it’s possible you’ll end up buying the same problems you already own. That makes rebuilding your starter a good option, and fortunately, kits like the one we got from Honda specialists Common Motor Collective are readily available. The $65 kit we purchased is very comprehensive, with all new wear and service parts including a new drive-end bearing and seal, a new brush plate assembly with brushes, starter housing O-rings and gaskets, planetary gear bushings, the armature support plate bushing, the rear cover bushing, and new fiber gaskets and replacement nuts for the starter battery cable post.

Save for the hassle of having to remove the left side cover, which also houses the alternator, removing the starter on the CB450 is relatively easy. The side cover must be removed, as it’s otherwise not possible to re-engage the starter drive chain once the starter has been removed, as the photos will make clear. First, however, you have to remove the shift lever, followed by the drive chain sprocket cover. Make sure to have a new side cover gasket on hand, typically around $12-$15. Once the starter has been removed, make sure the armature and field coils are good before going any further. You can research how to confirm all of this for yourself using a simple multimeter, but we took both pieces to our local automotive electrical shop, where a quick test confirmed that 1) the armature was running true and the windings weren’t broken or damaged; 2) the commutator end was in good condition with even resistance, needing only a light sanding to clean up the contact face; and 3) the starter field coils were good. If it hadn’t passed these tests, we would have had to look for a used starter and start over.

How To

Getting all parts clean before reassembly is paramount. Brake and electric parts cleaner works best here; just remember it’s nasty stuff, so wear gloves and work in a well-ventilated area. Although not technically complicated, this can be a challenging project as it involves a fair amount of detail. Although the photos don’t show it very well, note that the brush plate keys to the starter body for proper alignment.

We suggest giving yourself a full morning or afternoon so you don’t rush the job; give yourself time to work slowly and carefully. If you can do that, you shouldn’t have any problems, and you might even find it a fun challenge. This project doesn’t require any special tools, although we strongly suggest having the proper JIS “Phillips” drivers and an impact driver for removing the necessary fasteners, especially the neutral switch, which also secures the alternator wiring. A small bench-top tool press comes in very handy, but you can get away without it; you just won’t have as much control when it comes time to press in new bushings and such.

As ever, we recommend having a good shop manual on hand for parts identification and proper torque specs.

How To

1. Disconnect the negative lead to the battery. Disconnect the positive battery lead at the starter (the post is just visible on the end of the starter, under the left exhaust header). Remove the two bolts securing the starter. Remove the starter.

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2. Remove the gear shift lever, then the final drive cover. Remove the two screws securing the neutral switch above the sprocket, which secures the alternator wiring. An impact-type driver is recommended as the JIS “Phillips” screws can be tight. The neutral switch is keyed. Note its orientation for reinstallment.

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How To

4. With the starter on the workbench, remove the two long bolts holding it together. If the bolts are tight, use penetrant and an impact driver. Remove the bolts, then the rear cover.

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5. Place the starter upright on the drive end. Remove the screw securing the lead from the starter motor field coils to the brush assembly.

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How To

6. With the brushes still in place, lift the brush assembly and plate straight up and remove it from the starter. Remove the thrust washers from the end of the commutator. Clean and set them aside for reassembly.

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7. Remove the drive end of the starter. The drive end is a planetary gear set for starter drive reduction. The starter motor spins the two smaller gears, which spin the starter output shaft. Remove the two small gears and set aside.

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How To

8. Remove the armature support plate and any thrust washers under it. Remove the armature and clean it using electric parts cleaner.

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How To

9. Flip the drive end over. Remove the keeper ring for the end bearing, then the snap ring on the output shaft. Push the output shaft free of the drive end housing. Remove the thrust washer from the shaft. Clean it and the shaft and set aside for later reassembly.

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10. Place the housing on wooden blocks or a vise (as shown) and drive out the end bearing using a flat punch. It should come out fairly easily.

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11. With the bearing removed, use a seal extractor or suitable tool to remove the drive housing seal. Thoroughly clean the housing.

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12. The original bearing features a metal shield on the engine side, while the replacement bearing has rubber shields on both sides. It could be argued that change makes the starter seal unnecessary. Regardless, we did install the new seal, which should be pushed into place with the open side up.

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13. With the seal seated in the housing, install the bearing using a bearing driver, making sure it’s inserted deep enough for the securing clip to be installed. Install the clip. Push the output shaft with thrust washer installed back into place and reinstall the snap ring.

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14. To remove the bushings in the planetary gears, we supported the gears on a suitably sized socket (open end up), then used a small press and a 1/4-inch drive, 5/16-inch deep-well socket to push the old bushings out.

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15. The new bushings are chamfered at one end to ease installation. Start the bushing by hand making sure that it’s square with the gear, then press it fully home using the press.

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16. Install the rebushed gears onto the output shaft, making sure they turn freely on their posts and that the entire gear assembly turns freely. Lubricate the gear teeth with grease.

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17. Clean the armature support plate, removing any old gasket material. Press out the shouldered bushing in the plate, then press the new bushing in with the shoulder in the same orientation. Install the new support plate gaskets with the narrow gasket facing out and the wide gasket to the inside of the starter.

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How To

18. Slip the cleaned armature back into the starter body. Install any thrust washers removed earlier, followed by the armature support plate. Loosely install the drive end housing.

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19. To remove the rear bushing, we first tapped 8mm threads into the bushing. We then threaded a bolt into the bushing, through a flat plate placed over the cover opening. Tightening the bolt pulled the bushing out easily.

How To

How To

20. With the bushing out, remove and save the felt oil wick as the kit does not include one. Clean the cover. Reinstall the wick and press the new bushing in flush. Oil the bushing.

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21. Stand the starter on the drive end. Install the new O-ring seal on the starter body. Pull the brush springs back and slip the brush plate over the commutator. Ensure the coil wire aligns with the insulated brush set and the tang in the plate aligns with the notch in the starter body. Attach the field coil wire.

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22. Replace the thrust washers removed earlier. Smear a thin film of oil on the end of the armature shaft. Install the rear cover, making sure the brush plate is properly aligned.

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23. With the rear cover in place, install the two long Phillips bolts through to the front housing and screw them home tight. Turn the starter by hand to ensure it does not bind.

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24. Install the new O-ring on the drive end housing and grease lightly. Remove the old starter cable nuts and insulators and replace them with the new ones in the overhaul kit.

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25. Hold the starter drive chain and sprocket in position and install the starter, making sure the sprocket and starter drive ends spline together.

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26. Secure the starter with the two bolts. Ensure the sealing surfaces for the engine and side cover are clean. Install a new gasket. The dowels will hold it in place. We did not use any sealant.

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27. Finally, reinstall the side cover with the alternator, the alternator wiring securing plate, the final drive cover and the shift lever. Secure the positive battery lead to the starter. Connect the negative lead to the battery. If everything went right, your starter should spin right over.

Installing an Electronic Ignition on a 1973 BMW R75/5

We appreciate that many BMW owners are perfectly satisfied with their stock breaker points ignition system, but we also think that upgrading to electronic ignition is desirable if you ride your old airhead regularly. For one, the stock points on the /5 are hard to adjust. Camshaft actuated, they’re obscured by the mechanical advance unit, making confirmation of proper gap difficult. Further, showing almost 80,000 miles, our subject 1973 R75/5 was developing an odd propensity for points slip, likely from the points lift block wearing. The points were new BMW replacements, but were requiring regular adjustment. And while the mechanical advance unit looked to be OK, with good springs and no indication of undue wear, it appeared to be hanging up, sometimes sticking at full advance.

BikeMasterFollowing our excellent experience with Euro MotoElectricscharging system upgrade for the BMW /5, we decided to check out their EnDuraLast Electronic Ignition upgrade for the /5 and later airhead boxer twins.

This isn’t a difficult project, but it does require patience. The trigger and sensor are easy to install and the sensor wires route out the top of the front cover. To aid routing, we cut a relief in the grommet for the charging wires and ran the sensor wires alongside them, making sure they wouldn’t be pinched when the front cover was installed. A dab of silicone seals it up. 

The control module has three curves. Curve 1 is the default and provides 34 degrees of advance. Curve 2 is for dual-plug heads and provides 28 degrees advance and Curve 3 (which is what we used) is in the middle, providing 32 degrees advance and a slower advance rate than Curve 1. An optional 9-curve module is also available. Installing the module was straightforward and ignition timing was a cinch: With the engine on top dead center, slowly rotate the trigger wheel clockwise until the gap in the wheel passes the sensor and the red light on the sensor board illuminates. Continue to rotate until the light just goes out. After locking the trigger wheel in place, a check with a timing light showed we were absolutely spot on. 

One important note: The otherwise excellent and detailed installation manual says to remove the spark plug caps before adjusting the trigger wheel. This is incorrect, a point verified in a phone call to Euro MotoElectrics. The spark plugs must be connected and grounded, otherwise the module could be damaged when it fires. Never remove a plug lead from a running engine with this system. Also, as the optical sensor is light sensitive the ignition system will likely drop out if the sensor is exposed to direct sun during tuning or, say, a test ride, with the front cover off.

A side benefit of the system is the fact that you can leave the stock points and wiring in place as a backup in the unlikely event of module or sensor failure. If that happens, simply disconnect the module from the circuit, reconnect the points lead at the coil and reinstall the mechanical advance unit, although our guess is you’ll never need or want to revert back to points. 

Importantly, our subject R75/5 has never run better, with quicker starting and absolutely solid performance across the rev range. 

As always, we recommend having a good shop manual on hand for parts identification and proper torque specs.

1. Disconnect the negative lead to the battery. Disconnect the fuel lines and remove the gas tank. Remove the three 5mm Allen head bolts securing the front cover, then remove the cover.

2. Remove the 10mm nut securing the mechanical advance unit. Remove the advance unit and replace the nut, being careful not to over-tighten it. You can leave the points in place as a backup; they’ll no longer be actuated.

3. Since we left the points in place, we also left the wiring to the points in place. The points must be taken out of circuit, however, so we disconnected the points grounding lead at the right hand ignition coil, leaving the wire accessible.

4. Next, remove the 6mm Allen head bolt securing the alternator rotor. It will usually break free with a sharp rap on a socket handle. If not, put the bike in gear and lock the rear brake.

5. Replace the original washer on the alternator Allen bolt with the washer in the kit. Next, insert the bolt and washer through the trigger wheel hub.

6. Lightly coat the bolt threads with thread locking compound. Install the bolt with the trigger wheel hub. Torque the bolt to 14ft/lb, slightly less than stock owing to reduced thread engagement due to the trigger wheel’s thickness.

7. Remove the two screws securing the alternator wiring connector plate. Note the Y post at left. As the next photo shows, we had to shift the position of its lead to make room for the sensor.

8. Put the sensor assembly in place on top of the connector plate. Using the two Allen head bolts with washers included in the kit, secure the sensor assembly and connector plate. 

9. Next, slip the trigger wheel in place over the trigger wheel hub, centering the disc in the black sensor pickup slot. Lightly tighten the two small Allen head screws to secure the trigger wheel. The exact position of the trigger wheel will be set later.

10. Route the sensor harness to and through the top of the front cover. We cut a small relief in the grommet for the charging wires, making sure the sensor harness wouldn’t be crimped by the cover once installed.

11. The kit includes three separate wires; brown wire for ground, black wire to ignition coil negative terminal, red wire to ignition positive power supply. With a soldering iron, tin one end of each wire. This ensures a positive connection when connected to the module plug.

12. Following the manual instructions, install the wires as shown in the module plug and secure the clamping screws. From left to right: red ignition power supply wire; small white sensor unit wire; small yellow sensor unit wire; small brown sensor unit wire; brown ground wire; black negative coil wire.

13. Using the included hook-and-loop material, mount the module under the rear of the top frame tube, toward the seat. Secure with the included zip ties. Plug the harness into the module and zip tie the wires together.

14. We needed an additional spade terminal on the positive side of the left coil for the red power lead to the module so we added a terminal from an old coil, then connected the red power lead after crimping on one of the supplied spade connectors.

15. Next, crimp one of the supplied spade connectors onto the black lead from the control module and connect it to the negative terminal on the right coil. 

16. Crimp one of the supplied ring connectors to the brown ground wire from the module. We secured the ground wire at the front mount of the left coil, pairing it with factory ground wires already located there.

17. Set the engine at top dead center, “OT” on the flywheel. Reconnect the battery. Turn the ignition on. Loosen the trigger wheel. Rotate the trigger wheel clockwise until the red LED on the sensor lights. Continue slowly until the trigger wheel opening passes the sensor and just turns off the LED. Lock the trigger wheel set screws in place.

18. Start the engine. Using a timing light, check ignition timing at idle and full advance. We were spot on, requiring no further adjustment. Remove the trigger wheel set screws one at a time, coat with thread locking compound and reinstall. Disconnect the battery. Reinstall the front cover. Install the gas tank and reconnect the battery. Go ride.

Replace Honda CB450 Swingarm Bushings

Honda CB450 swingarm bushings have a reputation for wearing out prematurely. Early CB450s like our subject 1970 CB450K4 used metallic bushings, while later ones apparently switched to plastic, a material more than a few manufacturers embraced for ease of installation.

Whether early or late, CB450 swingarm bushings don’t appear to last more than 10,000 miles or so. Our subject bike doesn’t appear to have led a particularly difficult life, yet with a mere 13,000 miles showing on the clock the swingarm bushings were shot, exhibiting an easy 1/8 inch or more of slop on the swingarm pivot pin. Although a small amount of play won’t show adverse effects, too much results in a wandering rear end, the back wheel moving left and right, generating an uncontrollable steering input. Typically, once the wear becomes great enough to notice, it accelerates rapidly.

As originally fitted, the swingarm on the CB450 (and many other Hondas, including the CB500T, CB500 and CB550 Four and all pre-1979 CB750s) had a single bushing on either side of the swingarm followed by a felt sealing washer, a thrust bushing and an outer metal dust cap. Original replacement bushings are still available, but experience shows that if you’re actually riding your bike you’re wise to consider fitting aftermarket bronze bushings like the ones we sourced from Honda specialists Charlie’s Place.

The bronze bushings from Charlie’s Place do away with the felt sealing washers and the thrust bushings, and at $70 a set they are only marginally more expensive than stock (typically around $55-$65 for bushings, thrust bushings and felts), and thanks to their superior material it’s unlikely you’ll ever replace them again. BikeMaster

Better yet, the bronze bushings are very easy to install. The factory bushings have no shoulder, requiring the installer to ensure they’re properly inserted to the correct depth inside the swingarm. The bronze replacement bushings are shouldered, making insertion installation much easier: Just press them in until they seat.

While installation is easy, the old bushings can be difficult to remove, particularly the early metallic style, which can become seemingly welded to the swingarm. The solution is often to cut them out or press them out with a hydraulic press, if available. Thankfully, ours removed quite easily using nothing more than a hammer and a blunt punch.

As we show, installation is a snap, but you might have to give the bushings a quick pass with a small brake cylinder hone to get a proper fit for the swingarm pivot. The bushings are a light interference fit with the swingarm, so they tend to compress slightly. If you have to hone them, do so in short passes, checking the fit of the swingarm pivot pin frequently. You don’t want to remove any more material than necessary for the pin to slide into place.

This is a fairly straightforward job, easily within reach of the average weekend mechanic. The only special tools you might need are a small 3/4-inch to 2-inch brake cylinder hone and a torque wrench for final tightening. Budget a morning to get the job done, and as always, we recommend having a good shop manual on hand for parts identification and proper torque specs.


1. Put the bike on its centerstand. Disconnect the chain. Disconnect the brake stay at the brake hub. Disconnect the rear brake actuating rod. Remove the rear axle cotter pin, loosen the axle nut and then remove the rear axle and finally the rear wheel. Remove both lower shock absorber mounting bolts.

2. Remove the swingarm pivot bolt nut on the left side of the swingarm.

3. The end of the swingarm pivot bolt is dimpled. Using a suitably sized punch, gently knock the pivot bolt through the swingarm. Remove the bolt.

4. With the pivot bolt removed, pull the swingarm straight back and free of the frame. To give ourselves a little more working room, we removed the left shock. Although we didn’t, removing the chain guard simplifies chain installation.

5. Once the swingarm is free, remove the dust caps and thrust washers (thrust washer pictured). Set the thrust washers aside; you won’t use them with the new bronze bushings.

6. Next, using a suitable drift, remove the swingarm pivot pin. It should knock out easily, but accumulated grease, dirt and corrosion can make it a little stubborn to remove.

7. Here’s our pivot pin after knocking it out of the swingarm. Thankfully, it cleaned up well, as replacements are getting quite difficult to find.

8. With the pivot pin knocked free, remove the felt sealing washers at either end of the swingarm and discard them. The new bronze bushings don’t use these.

9. Next, remove the old bushings. Ours pushed out fairly easily using nothing more than a blunt-ended punch and a hammer, but they are known to be difficult to remove, sometimes requiring a hydraulic press to push them out or a hacksaw blade to cut them out.

10. Here’s one of our old bushings removed from the swingarm. Before moving on to installing the new bushings, clean any debris or grease from the inside of the swingarm tube.

11. Next, install the new bushings. We pressed them in using a simple homemade tool made up of a piece of all-thread rod, with washers and nuts at each end, steadily tightening the nuts until the shoulders of the bushings seated against the swingarm.

12. Here’s one of the bushings fully seated in the swingarm. With the new bushings installed, we found the swingarm pivot pin to be a tight fit.

13. To make the swingarm pin a sliding fit in the bushings, we lightly honed them with a small brake cylinder hone, removing only enough material to allow a tight sliding fit. After honing, thoroughly clean the bushings with brake parts cleaner.

14. With the bushings honed, our swingarm pivot pin (visible inside the bushing) slipped into place. With the pivot pin installed, lightly grease the dust caps and install them on either side.

15. Using a grease gun, push the old grease out of the swingarm pivot bolt until only fresh grease comes out of the lubricating holes in the bolt.

16. Push the swingarm back into place in the frame, then insert the swingarm pivot bolt through the swingarm from the right side.

17. With the swingarm pivot bolt in place, thread the pivot bolt nut onto the bolt and then torque it to 51-65ft/lb. We went for the middle of the range, 58ft/lb.

18. Next, using a grease gun, grease the swingarm pivot until fresh grease just starts to show around the dust caps. Reinstall the rear wheel, the drive chain, the brake stay and the brake linkage. Adjust the chain as necessary and tighten the axle nut, making sure to reinstall the cotter pin.

Replace Norton Commando 850 Clutch Plates

If you’re actually riding your old Norton Commando 850 — and we hope you are, because they’re one of the great bikes of the ’70s — chances are good that at some point you’ll have to replace the clutch plates. The original setup used five alternating bronze friction plates keyed to the center clutch hub, with four plain steel plates keyed to the outer clutch drum followed by a pressure plate and a single diaphragm-spring plate compressing the plates. It’s a fine setup, but eventually the plates wear. Slippage and overheating take a toll, as well: Once the steel plates start to blue, they’re toast, and both the steel and the bronze plates can warp from overheating.

The good news is, replacement clutch plates are readily available and the design of the Norton clutch makes servicing quite simple. Only one special tool, a diaphragm spring compressor, is required. You can buy the tool for $26 from, or you can make your own if you want (go here to see how).

BikeMasterThere are a few points to appreciate, one of them being the stacked height of the clutch plates. According to various sources, Commando 850 clutch plates should have a stacked height — the total thickness of all the plates stacked together — of approximately 1.17 inches. However, replacement clutch plates (even stock Norton items) rarely stack out to that exact specification. The height matters because of the nature of the diaphragm spring clamping the plates together. A shorter stack allows the spring plate to push farther into the clutch hub, resulting in a stronger pull at the clutch lever, while a taller stack means the spring plate is flatter, resulting in a lighter pull. That makes a taller stack desirable, but only to a point. If the stack is too tall the clamping pressure is reduced, increasing the risk of clutch slip. Back in the day, variations in stack height were routinely balanced by inserting a fifth steel “shim” plate to compensate, but shim plates are now hard to find.

So what to do? Well, as we discovered with our Barnett plates, which had a stack height 0.145 inches shorter than recommended, there’s lots of room for variation, as our installed clutch requires only moderately strong pull and shows every indication it will work just fine. Bottom line: As long as the installed assembly is below the diaphragm spring retaining clip, you’re probably fine.

As noted, we sourced all our plates from Barnett, known for quality clutch parts. The Barnett friction plates are fiber, not bronze, which brings up the age-old issue of whether to run the clutches in engine oil or, as some prefer, automatic transmission fluid. Barnett notes that their clutches are made to run in engine oil, but are also designed to work in ATF, as well.

As to cost, Barnett sells the friction plates as a set for $65.53, while the steel plates are sold individually at $8.10 each. Primary case gaskets are readily available from a variety of sources for $4-$5. As always, we recommend having a good shop manual on hand for parts identification and proper torque specs.


1. Remove the three nuts and washers securing the brake/foot peg assembly to the aluminum sideplate. Remove the brake/foot peg assembly. Place a drain pan under the primary cover. Using a 13/16in socket, remove the center primary cover securing nut. Remove the primary cover and let the oil drain.'

2. With the 13/16in socket, loosen the clutch adjuster lock nut. If it’s stuck, give the socket wrench a quick rap with a hammer. It should shock loose easily. Unscrew the clutch adjustment screw.

3. Next, install the clutch diaphragm removal tool. Screw the center bolt into the clutch to engage at least five threads. Lock the bolt with its lock nut. Next, tighten the outer nut while holding the bolt until the clutch diaphragm spins freely in the clutch hub.

4. Next, remove the wound circlip securing the diaphragm. The circlip has a slotted opening in its free end. Insert a screwdriver into the slot and pull the circlip toward the center of the clutch hub, then pull the circlip free.

5. The clutch diaphragm should now simply fall out, exposing the outer clutch pressure plate. Note the clutch adjustment rod protruding from the center of the clutch hub.

6. Next, remove the outer clutch pressure plate, examining it for any signs of scoring. If it’s badly blued from being overheated, consider replacing it as it could be warped.

7. Next, remove the clutch plates. There are five bronze friction plates and four steel plates. The plates alternate, starting with bronze and ending with bronze. On bikes with any kind of mileage, these will generally show signs of scoring and/or overheating.

8. The Commando 850 clutch works best with a stacked height of approximately 1.17in. A thicker stack equals a lighter pull, but also introduces the risk of more slip, which causes overheating and wear. Our original plates had a stacked height of 1.053in.

9. Our replacement Barnett plates had a stacked height of 1.025in. Although shorter than the stock recommendation, they worked fine and with good pull at the clutch handle. It was once standard to insert a fifth steel plate of the needed thickness to make up the difference. However, custom steel “shim” plates are no longer available.

10. Before installing the new fiber plates, soak them for a few minutes in quality engine oil or automatic transmission fluid, depending on what you plan to use in the primary case.

11. Drain the plates after soaking. Wipe off excess oil with a lint-free cloth. Install the new plates, starting with a fiber friction plate and alternating with steel plates, ending with a fiber friction plate.

12. With the new clutch plates installed, install the outer pressure plate. If reusing the original, lightly scuff the surface with a Scotch-Brite pad and then clean it with brake parts cleaner or similar before installing.

13. Next, with the removal tool still attached, place the diaphragm spring in place, then secure it with the large wound circlip. Make sure the circlip is seated in its groove, then loosen the outer nut on the tool to release the diaphragm. Remove the tool.

14. Before installing the clutch adjuster, remove the inspection cover on the right outer transmission cover. Make sure the clutch release arm is properly located and that the cable is secure as shown.

15. Screw the adjuster into the center of the diaphragm and loosely fit the locking nut. Screw the adjuster in until it just touches the release rod, then screw it back out 1/8-1/4 turn. Lock the nut in place.

16. Remove the larger primary cover rubber “O-ring” seal. Clean the groove it sits in, then install a new seal. When installing the new seal, place the bonded end joint at the highest point as shown to diminish the chance of an oil leakage from the primary cover.

17. To further discourage oil leakage from the primary, place a suitably sized O-ring over the outer primary cover stud. The O-ring will crush when the outer cover is installed.

18. Finally, fill the primary cover with 300cc of quality engine oil or, if preferred, automatic transmission fluid. Reinstall the brake lever/foot peg assembly.

DIY Norton Clutch Hub Compressor

Our homemade Norton Commando clutch hub compressor tool (at right) next to a factory tool. It may not be as sleek, but it works just as well.

If you’re servicing the clutch on your Norton Commando, a clutch hub compressor tool is a must. The Norton Commando clutch is a simple, robust design utilizing a single diaphragm spring to clamp the clutch plates together. Although factory-style clutch hub compressor tools are readily available and reasonably priced, (typically $25-$45), if you’re like us you get a certain kick out of making your own tools when you can, and this is one tool you can easily make, usually for less than $10 if you already have much of the hardware sitting around, as many of us do.

To make the compressor here, you’ll need:

• 1 x stick of fine-thread 1/2-inch all thread or a 5-inch 1/2-inch threaded bolt
• 1 x 1/2-inch bolt washer
• 1 x 1/2-inch fine-thread steel (not nylon insert-type) lock nut
• 2 x 1/2-inch fine-thread nuts
• 1 x 4-inch PCV pressure cap
• Medium (blue) thread-locking compound

Here’s all it takes to make the tool: a 5-inch OD PVC slip cap (shown here with center hole already drilled), a 5-inch bolt or piece of all-thread, and a few nuts and washers.

Making the compressor is simple.

• Take the PVC pressure cap and drill a 1/2-inch hole directly through the center of the cap. The pressure cap we used is rounded at the top instead of flat. You can use a standard slip cap, which is flat at the top, but we like this type better as it’s a little stronger. If necessary, trim the cap to an overall length of 3 inches. The cap we purchased was already at this dimension.
• Cut a 5-inch piece off the all-thread stick or use an existing 1/2-inch fine-thread bolt, making sure the threads are clean and serviceable.
• If using all-thread, thread the two standard nuts onto one end of the all-thread and then tighten them against each other to lock them in place. Clamp the end threaded with the two nuts in a vice to hold it firmly. Apply locking compound to the other end of the all-thread, then thread the steel lock nut onto the all thread until it’s fully on engaged on the all-thread and locked in place.
• Loosen the two nuts you jammed together. Remove the lower nut, then thread the upper one up to the lock nut. Install the washer under the nut then insert the threaded shaft through the top of the PVC cap. Thread the second regular nut onto the threaded shaft. That’s it; you’ve made your Norton clutch hub spring compressor.

Drill a 1/2-inch hole through the center of the PVC pressure cap. If necessary, trim the cap to an overall length of 3 inches.

Cut a 5-inch piece of 1/2-inch fine-threaded all-thread (or use a 5-inch bolt if you have one). Clean the threads and apply locking compound to one end.

Lock two regular nuts to one end of the all-thread, lock the piece in a vice, then thread the steel lock nut onto the all-thread until it’s fully engaged and locked in place.

Release the two regular nuts. Remove the lower one, then thread the upper one up to the lock nut and install the 1/2-inch washer.

Insert the center bolt through the PVC cap and thread the second regular nut onto the center bolt.

The homemade spring compressor assembled and ready to work.

Using the clutch hub compressor

To use the tool, remove the center adjuster screw from the clutch diaphragm spring hub. Place the clutch hub compressor loosely over the diaphragm spring. Thread the clutch hub compressor center bolt into the diaphragm spring hub, making sure at least five of the bolt threads are engaged in the hub. Jam the nut on the clutch tool center bolt tight to the spring hub. Next, hold the clutch hub compressor bolt while tightening the standard nut against the washer and PVC cap. As the nut is screwed tighter the clutch diaphragm spring will be pulled flat. Tighten slowly until the diaphragm spring releases and spins in the clutch hub. Remove the diaphragm retaining circlip, followed by the diaphragm spring.

To use the tool, remove the clutch hub adjuster screw then screw the clutch hub tool into place making sure at least five threads are engaged in the diaphragm spring hub.

Jam the lower nut against the diaphragm spring hub to lock the center bolt in place.

Hold the center bolt and tighten the outer nut until the diaphragm spring pulls flat and spins in the clutch hub. Remove the diaphragm spring circlip.

The Norton clutch diaphragm spring removed.