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Tech Corner
Technical Q and A for classic motorcycle maintenance and repair.

1966 Triumph TT Ignition

Motorcycle Classics tech expert Keith Fellenstein 

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

 

Triumph ignition

Q: I have a 1966 Triumph TT with an ET ignition system. I have a five-wire stator and the armature has three holes in the back; S, M and R. Which one is the best for timing for street use and ease to start? How do I install the five-wire stator? It seems to me the end connections must be removed to get the wire through the opening in the tube. I am thinking the tube would be slipped on, then the ends soldered on. — Andy/via email

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A: The first part of your question is easy; the hole next to the S mark should be used to pin the rotor to the crankshaft for best timing for everyday use. The other two are for racing and will make it hard to start while giving better spark at high rpm. On the wires from the stator, you can remove the bullet connectors, but I’ve had good luck feeding the wires through one at a time. If the insulation has stiffened with time, careful use of a heat gun can soften the wires to make them flexible.

Finding Spark on a 1980 Suzuki GS850

Motorcycle Classics tech expert Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Finding spark

Q: I’m having trouble getting spark at the plugs on my 1980 Suzuki GS850. At first I wasn’t getting any spark, so I replaced the igniter unit. It then had spark, but when I installed the carburetors and tried again, there was no spark. What should I do? — Tyler Hubenthal/via email

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A: We’ll consider the igniter a good part. Get your volt-ohm meter (VOM) and check from the battery to the igniter for voltage. From the battery, there should be two wires: one to the starter relay and a second, smaller lead to the fuse box. Follow the smaller lead to the first junction, disconnect and test for 12 volts from the battery. If good, reconnect and follow that lead to the fuse box. Test the 15-amp circuit on both sides of the fuse for 12 volts. That leads to a multi-pin connector that leads to the ignition switch. If I can trust the colors on the wiring diagram I have, the 12-volt lead into the switch is red, out is orange. Orange leads back to the fuse box where it branches to feed three 10-amp circuits. The one we’re interested in looks to me like orange/white. Test both sides of the fuse for 12 volts with the ignition switch on. Next is the emergency stop, or kill switch. Test for 12 volts on the orange/white wire leading in and out of the switch. Now check the orange/white leads at the coils for 12 volts with the ignition switch on. Now we end up at the igniter. Test the orange/white lead there for 12 volts with the ignition switch on. Assuming you find 12 volts or slightly less at each of these test points, switch ranges on the VOM and test the signal generator that triggers the igniter module. You’ll find the connector under the left side cover. Put the VOM in resistance testing mode, set to 100-ohm range if not auto ranging and put one probe on the blue lead and the other on the green lead after disconnecting them from the igniter module. Look for a reading of between 250-350 ohms. If very low (0) or higher than 350, the signal generator is bad and needs to be replaced. Finally, pull number 1 and 2 spark plugs and rest them, connected to their high-voltage leads, on the cylinder to ground them. Set your VOM in resistance test mode to the 1 ohm range. With the ignition switch on, touch the plus probe to the blue lead, and the minus probe to the green lead on the harness side of the interconnect for the igniter. Number 1 should spark when you connect the second lead, and number 2 should spark when you disconnect it.

Motorcycle Battery Worries

Motorcycle Classics tech expert Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Battery worries

Q: I just went out to start my bike, turned the key and got no lights at all. I attached a battery charger and my USB port LED lights up, but I’ve still got nothing else lit. What should I check for? — Bob Gent/via email

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A: The first thing I’d check would be the charge level of the battery. Anything less than 12 volts and you definitely need to charge it. Next, I’d check the electrolyte level of the cells. If the electrolyte level is low or has been boiled off due to overcharging, the battery may show 12 volts, but have very little ability to push current, and current is what you need to make the incandescent bulbs in your bike light up. Your LED lights up because it requires milliamps of current where your incandescent bulbs require more. If you do find the electrolyte levels are low, go ahead and charge the battery. After it’s charged, add distilled water to each cell to bring them back to acceptable levels. If you do all this and still get no lights, have a look at the fuse box. MC

1979 Triumph Bonneville T140E Wiring

Motorcycle Classics tech expert Keith Fellenstein 

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Bonneville wiring

Q: I have recently acquired a pristine original 1979 Triumph Bonneville T140E 750. It has been in storage since 1981. I am having difficulty getting fire to the plugs. This bike has a Lucas pointless system and I haven’t been able to find a manual that provides info for this particular system. I’m relatively certain the ignition module is shot as there is no fire at the spark plug. There is power to the module. Without specific info concerning the Lucas components, I cannot be certain what to replace or not. So far, I haven’t found the “E” designation on any of the manuals I’ve researched. It’s my understanding that is the emission compliant version for the model years 1978 through 1983, hence the electronic ignition. –  Dale Lawless/via email

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A: Your T140E is indeed the emissions compliant version of the 750 twin. It would have the Lucas Rita electronic ignition, which has been out of production for many years. If it has failed you have a variety of options for replacement, including Sparx, Pazon, Boyer and Tri-Spark, to name a few. But before you replace the system, let’s run through a few tests to see if there’s a simple fix. We’ll start with the trigger, found in the cavity on the right side of the engine where the points would be on a standard ignition. You probably have the type used with the AB11 amplifier. Disconnect the leads to the trigger and using a volt ohmeter (VOM) set to read ohms, measure the resistance across the leads to the trigger. It should be in the range of 600 to 700 ohms. Reconnect the trigger. Next, remove a plug or attach a spare spark plug to one of the high tension leads. Lay the plug on the cylinder head. Turn the ignition key on and off, this should produce a spark at the plug. Next, check for voltage at the left coil by switching the volt ohmmeter to DC volts. Place the positive probe on the positive terminal of the left coil, and ground the negative lead of the VOM to frame ground. With the key on, you should read 12 volts on the VOM. Move the positive lead to the negative terminal of the left coil and check the VOM again. Your voltage will drop slightly as you move from coil to coil, but an abrupt drop to 0 will indicate a bad coil. Move to the positive terminal of the right coil and check the VOM. This and the last reading from the negative terminal of the left coil should be the same as the coils are connected in series, with the negative of the left and the positive of the right directly connected. Move the positive lead to the right coil negative terminal for the last of this test and again check the VOM. Since the coils are connected in series, a failure in one coil will bring the whole circuit down. Finally, switch the ignition off, set the VOM to ohms and check the resistance from the right negative terminal to ground. It should read 0 ohms if the wiring is good. If none of these tests show the fault, the amplifier is probably bad and you’ll have to buy a new electronic ignition. Finally, disconnect the black/white and black/yellow leads that come from the amplifier to the coils and with the VOM set to DC volts, test each lead to ground. If both read 12 volts, the amplifier is bad. MC

Stuck on a Whitworth

Motorcycle Classics tech expert Keith Fellenstein 

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Stuck on a Whitworth

Q: My 1968 BSA 441 Victor has a nut that I can’t manage to remove. It’s the one down inside the fuel tank that secures the tank to the frame. The nut is rounded off. This seems like an impossible place to reach with my limited collection of tools. Any suggestions? – John Grenier/via email    

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A: I’ve run into this problem before, and at the time I had to carefully force a socket over the nut and then carefully unscrew it. An easier way would be to get a set of bolt extractors. These are specially machined sockets made to fit over a rounded bolt head and bite into it so it can be unscrewed. Individually they can be expensive, but you can buy an inexpensive set from BikeMaster.

1968 Triumph T100S Fork Oil Questions

Motorcycle Classics tech expert Keith Fellenstein 

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Fork oil questions

Q: I have a 1968 Triumph T100S and want to change the fork oil. I have taken the drain plugs out of the bottom of the fork legs and will let the oil drain for a day or so. For refilling, I have a few questions: I assume I take the nuts off at the top of the triple tree. My manual says to add 190cc to each leg. Do I just pour the oil in the top and replace the nut? What oil do you recommend to use? I have Harley-Davidson fork oil from my old Shovelhead days left over, would that be OK? Some people have advised to use ATF transmission fluid, but I don’t want to mess this up. John Schaub/via email

A: In addition to pulling the plugs and letting the oil drain, it’s helpful to pump the forks to get even more oil out. Unfortunately, with the drain holes pointing left and right, pumping the forks just about guarantees spraying oil all over the place. Once you’ve emptied the forks as much as possible, you do indeed just pour the oil in the top. You should either put a jack under the engine to support the bike while you remove both caps, or take the easy way out and just remove and replace one at a time. Either way you’ll have to compress the spring to get the cap back on the fork tube. That’s easiest if the bike is jacked up so the least amount of load is on the fork springs. Take your time pouring the oil back into the fork tubes as the oil will collect in the spring before trickling down into the lower stanchion. Your Harley fork oil should be fine, too, providing it’s 20w fork oil. After 1972 Triumph recommended ATF for fork oil, probably because is was a similar weight and easy to source. MC

1981 Yamaha XS650 Stalling Problems

Motorcycle Classics tech expert Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Stalling 1981 Yamaha XS650

Q: I’ve been enjoying your magazine for a number of years now, but this is the first time I’ve needed to write for mechanical advice. I have an essentially stock 1981 Yamaha XS650 Special. Outside of some initial carburetor issues when I first bought it, the bike has performed flawlessly, until now. I try to put a few miles on it every week or so, and last week when I took it for a spin the engine inexplicably died about 7 miles into the ride. No stuttering, sputtering or misfires; it just quit as if I had inadvertently hit the kill switch. I tried to restart it, and although it turned over with both the electric and kickstarters, it wouldn’t catch. I checked the fuel lines, vented the gas tank and checked the plug wires, but that is about the extent of my roadside mechanical acumen. About 15 minutes later, as I was waiting for my distress call to be returned, I tried it again and it started right up. Hopping on I headed home, but it died again after about 4 miles. I waited another 15 minutes, it started up, and I made it home just as it died again, after about another 3 miles. I’ve taken it for a test drive around the neighborhood and the same thing happened again. Because the problem comes on so suddenly and affects both cylinders, I suspect the ignition coil (my understanding is that this bike has a single coil), but before I start randomly replacing parts, I thought I might seek a little guidance. Any insights into this problem would be greatly appreciated! Jan Cordes/Yorktown, Virginia

A: I think you’re right about the ignition coil, and my guess is that it’s heating up and opening up either the primary or secondary side. It’s also possible the pickup coil in the alternator has gone bad. You can test the pickup coil by first disconnecting the plug between the air boxes. The plug should have black/white, white/red and white/green wires. With an ohmmeter, measure the resistance between the black/white and white/red leads, and again with the black/white and white/green leads. In both cases the meter should read between 550 and 850 ohms. Ideally you’d test this as quickly as possible after a failure, since your failures seem to be heat related. If that tests out OK you can proceed to test the ignition coil, but you’ll have to remove the tank to do that. Probing the primary side of the coil (the side not connected to the plugs) should result in a reading just shy of 3 ohms. Checking the secondary or spark side your readings should be somewhere in the 10,000 to 20,000 ohm range, depending on condition of the resistor plug caps. If after all this testing you find those components are fine, the only thing left is the TCI unit, which can’t be tested by ordinary means. MC