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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject.  

BSA Victor issues

Q: There are only 2,500 original miles on my Victor. Since it only gets ridden occasionally in the summer I have drained all the fluids and replaced them. From new, this machine has always had a loud valve noise (I’m presuming that’s what it is), which I have accepted as normal. However, since setting the points gap, cleaning the carb and replacing the fluids, I have acquired a new disturbing clinking sound when I accelerate moderately hard. I’m still not clear on timing, so I have left that alone. It is a higher sounding “tinkling,” almost like pennies rattling around somewhere in the top end. Once up to speed and just riding it is gone, but as soon as I crank it on it sounds off. The spark plug is a perfect color, and the exhaust is clean with no smoke of any kind at any time. The tailpipe has a slight amount of grease in it, but it is fairly dry and the same as it’s always been. Other than the noise, the bike sounds, accelerates, rides and responds the same as it always has. Before setting the points gap, upon kickstarting, the machine made some bucking sounds during one of its periodic kick backs. Could something have been damaged? Or is the points gap setting causing this? Under “specifications” in the owner’s manual it says the points gap should be 0.020-0.025in. However, on another page it says the points should be set to 0.015in. Do you know what the correct setting is? — Larry Bush/via email 

A: The 0.020-0.025in will be for the spark plug; there may be a misprint in the manual. Most points for any motorcycle will be in the 0.012-0.016in range, and I usually strive for 0.015in. If you have the points set to 0.020-0.025in, you will have overly advanced the timing. That leads me to the new noise. It sounds to me like you have “pinging,” the common term for the noise you hear when you have detonation/pre-ignition. It’s a dangerous condition, one that can burn a hole in the crown of the piston and subjects the piston and connecting rod to explosive stresses they aren’t meant to have. It’s usually caused by one of two things: low-octane fuel or overly advanced timing. Start by re-setting the points gap to the proper 0.015in setting. The Victors were high-compression machines meant to run on premium, so fill it with premium fuel and see if the pinging remains. If it does, you will have to check and set the timing. Once the timing is correct, your bike should be easier to start and sound fine. Good luck! MC 

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject. 

Yamaha XV920 Virago troubles

Q: I have a 1983 Yamaha XV920 Virago. Two weeks ago, I over-revved the engine, and it ran just fine for the next 10 miles. After 10 miles I had to stop at a stoplight and the engine stalled. When I went to start it, my starter wouldn’t engage. The starter had been going out like Virago starters do. I replaced the starter and it works great. Now the bike will start but will only run on the front cylinder. My manual said I should clean the carburetors, which I did with carburetor cleaner, and I blew everything out with compressed air. The starting circuit was dirty, but the rest was pretty clean. Now the bike starts and runs better, but still just on the front cylinder. What should I do? I don’t want to throw parts at it until I get it running. Any help would be great. I use this bike to save gas, plus I like it and miss riding it. — Bill Porter/via email 

A: Since you mentioned over-revving the engine, let’s start with some simple engine checks. Too many times I’ve looked for complex solutions to simple problems, wasting a lot of time in the process. The first, simplest and least expensive test is to change your spark plugs. Sometimes a spark plug will show a spark in free air but refuse to fire under compression due to some minor fouling. A compression test on the cylinders could also help pinpoint the problem. Your engine in good shape should show compression of about 135psi per cylinder, and there shouldn’t be more than about a 20 percent difference between the cylinders. Poor compression can indicate a blown head gasket, piston ring problems or leaky valves. A leak down test after the compression test can further isolate low compression to any one of those causes. BikeMaster sells a universal compression tester kit, and you can get a leak down tester from Harbor Freight or Pit Posse. You may be able to borrow these tools from a local auto parts store. You also mentioned changing the starter, so check and make sure no wiring was disturbed when you installed the starter. After that, you can troubleshoot the rest of the ignition. You can usually test the coils with a multimeter as a first step to determine if they are bad. Set the meter to read ohms, disconnect the leads to the primary side of the coil, and connect the probes to the positive and negative terminals at the coil. Your meter should read approximately 2.7 ohms. Do the same thing testing the secondary side of the coil, connecting one probe to the spark plug lead and the other grounded to the coil’s negative terminal. Here the reading should be approximately 8,500 ohms. Less than that and the coil is shorted, more than that or infinity and the coil is open. Either way it won’t produce a spark. If your coil tests OK you’ll have to test the pickup coil and ignitor unit. The easiest location to test the circuit is at the ignitor box under your tank. The pickup coils should read between 124 and 186 ohms, and again, wide variance from this indicates shorted or open circuits. On your bike, the brown/green wire is the rear cylinder and the red/blue wire is the front cylinder. If possible, I’d swap the coils to see if the problem moves with the coil. Also, try moving the trigger wire and spark plug wire from the front coil to the rear coil and see if it still won’t fire the rear cylinder. If the bike then runs on the rear cylinder only you’ll know it’s the coil or spark plug wire. Keep at it and you’ll find the issue. MC 

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject. 

Triumph TR650 backfiring problem

Q: I’m having a backfiring problem with my old Triumph TR650 single carb. It had been sitting for a few years since I was using my other bike. I found that it had a blown head gasket that was leaking between the cylinders and also a stuck intake valve. I had the jug milled to fix a dip between the cylinders, which is what caused the head gasket to blow. I had the valves reseated, but I messed up the valve timing when I was making repairs. I followed the manual for matching the dots on the timing gears, adjusted the timing and added a new Mikuni carburetor. It now starts right up, but it backfires on acceleration. I tried checking the valve timing. It appeared to be off, so I made some adjustments by moving the gears. I also replaced the spark plug wires and checked the spark by cranking the engine through. The magneto seems to be putting out lots of spark. Any recommendations? — Mike White/New Jersey 

A: This seems like a good question to follow the previous one. Now that you’ve repaired all the obvious mechanical faults it may be time to muck about with the carburetor. Before I jump to that conclusion, I have to assume that by backfiring you mean spitting back through the carburetor. If it does that at a certain RPM in any gear you may have to check your valve timing again. When I got my Norton it would idle just fine and run wide open, but it stumbled horribly just off idle and would top out at 5,000rpm. At about 2,500-3,000rpm, it would reliably spit back through the carburetors. I initially thought this was a carburetion issue, and I tried richening the midrange mixture. Opening up the timing chest showed the error of that thinking, as the cam was advanced one tooth from where it should have been set. Once I got that set properly it ran the way Norton intended. Looking at the shop manual for your bike, I really only see one setting that changes between your TR6 and the rest. On the intake valve side, make sure you have the long timing mark on the intermediate gear aligned with the dot on the intake timing gear. The single dot on the crankshaft nests between two dots on the intermediate gear, and the single dot on the intermediate gear aligns with a single dot on the exhaust timing gear. Assuming the valve timing is correct, it’s probable that your midrange is lean. Find out what needle and needle jet you are using. The recommended setup for a single carb 650 Triumph is a 240 main jet, between 25 and 30 for the pilot jet, a P2 or P4 needle jet, 6DH2 needle and 1.0 air jet. Check and see if you have the recommended 3.0 slide. There are subtle differences between the single carb and the twin carbs in the earlier Triumph carb question. MC 

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject.  

Commando electronic ignition 

Q: I have a 1971 Norton 750 Commando Roadster and want to go to electronic ignition. Do you have any recommendations? I’ve been to numerous websites and looked at what they are doing at Colorado Norton Works and other places, like Australia. I want to leave the external looks pretty much unchanged so I want to keep the coils. Any help would be greatly appreciated. I really enjoy reading your column in Motorcycle Classics. — Barry Pittman/Topeka, Kansas 

A: There are a variety of electronic ignitions to choose from. I’ve used two different brands and installed a third brand on a friend’s Commando. My 1974 Commando came with a Boyer, a decent enough ignition if a little old-fashioned. I changed it to a Power Arc optically triggered ignition I bought from Old Britts in Enumclaw, Wash., and I’ve been happy with it. If I don’t let the Norton sit for weeks between starting it, it will start on the first kick. I installed the Tri-Spark ignition on a friend’s Norton; it was the subject of the How-To article in the January/February 2012 Motorcycle Classics. His Norton is now also a reliable one-kick starter. The Tri-Spark and the Power Arc mount inside the stock points cavity of the engine, so there is no external indication that you have anything other than the stock points ignition. In both of these setups we opted to use a dual-output coil instead of the old Lucas coils, but you can use the Lucas coils with one change. Since all of these electronic ignitions are wasted spark, firing on the compression stroke for one cylinder as well as the exhaust stroke for the other, you wire the coils in series. In a 12 volt system, that requires using 6 volt coils so that the load on the battery and ignition is the same as if it were a discrete spark. Your current setup has two 6 volt coils in parallel along with a ballast resistor. You can keep the coils, but remove the ballast resistor and the points condensers. The ignition manufacturer’s instructions will spell this out in greater detail. I would recommend either the Tri-Spark or the Power Arc. They work well and with the right coils will keep your bike looking stock. MC 

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject. 

Mikuni jetting

Q: I own a 1979 Triumph T140E, and I have a pair of Mikuni 34mm VM round-slide carburetors that I would like to use on it. The problem is that I don’t know what size jets and needle to use. The bike is stock with the exception of a Boyer ignition and shorty mufflers. I am from Trinidad and Tobago in the Caribbean, so the temperature is very hot and I’m at sea level. The bike will be used as a daily rider and there are no emission controls here. Any advice would be greatly appreciated. — Brian Amow/via email  

A: I’m still running Amals on my bikes, so I did a little searching and found that the consensus for the T140 using twin Mikunis is 260 for the main jet, between 25 and 35 for the pilot jet, a P4 or P6 needle jet, 6DH3 needle and a 1.0 air jet. That will get you started, then you’ll have to fine-tune it for your temperature, altitude and humidity. The good and the bad about Mikunis is the near infinite amount of adjustments you can make changing main jets, needles, needle jets, air jets, slides and pilot jets — it’s difficult to know when to stop. As always, start by getting the main jet the right size at full throttle, then the idle mixture, and then the midrange. The midrange is where you will find most of the variables. Raising/lowering the needle, selecting a richer or leaner needle jet, and getting a needle with a different taper are all options for setting the midrange mixture. Good luck! MC 

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject. 

Triumph T100SS and an Energy Transfer System 

Q: I am now in the process of rebuilding my first bike. My 1963 Triumph T100SS Scrambler has no battery, as it runs on the energy transfer system. It hasn’t been on the road since 1986, when it got a pencil-sized hole in the right piston. All the books, maintenance manuals and online materials are too general, showing illustrations that do not match my engine or directing me to steps that do not apply to my particular bike. Have I just not been fortunate enough to find a truly appropriate manual, or were too many of the specifics of different models lost over time so that now all materials are just too generic? My engine number is H30587 and is stamped a T100SS. Can you direct me to any materials or sources of info you may have pertaining to these energy-transfer machines. — Kevin Gennario/via email 

A: It took me the longest time to really understand the ETC system; it’s so different from a standard battery/coil ignition. In fact, it’s closer to a CDI-type ignition than battery/coil. The biggest difference between the ETC system and battery/coil is the way the coils are charged and discharged. In a battery/coil system the alternator’s output is rectified from AC to DC and smoothed out to provide a steady level of voltage to charge and discharge the coils. In the ETC system the ignition voltage is taken directly from the alternator. Since the alternator is supplying the voltage directly, and it is alternating current, you have rising and falling voltage as the rotor spins inside the alternator coil. You want to fire the coils as the alternator is generating peak voltage. In a normal battery/coil ignition the points are in series with the primary side of the coil. Voltage charges the coil, then the points open, interrupting the primary coil circuit. The magnetic field collapses, inducing high voltage in the secondary windings, which is discharged through the spark plug. In the ETC system, the points are in parallel with the coils. The primary side of the coil is kept grounded until the alternator reaches peak voltage, then the points open, allowing the voltage to flow through the primary side of the coils. The surge of current induces high voltage in the secondary windings of the coil, which is discharged through the spark plug. Because you are taking the output of the alternator directly you want to time the peak alternator output to the instant of the points opening. This gives you a very narrow range of ignition advance and is why the points plate on an ETC system only allows a 5 degree advance. Just a few degrees one way or the other can really keep the bike from running well. The back of the ETC alternator rotor has three holes that can be engaged by the matching pin on the crankshaft. They are marked S, M or R. For most street use you will want to use the S setting, which puts the maximum advance at 37 degrees BTDC. The M and R settings are for racing and can make the bike difficult to start because they preset the advance higher than normal. This Triumph Service bulletin explains it all. MC  

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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as your subject. 

Take off the Aftermarket Carbs on a Suzuki GR650? 

Q: I’ve read your blogs and enjoy your knowledge of older bikes. I don’t know if you have worked much with Suzuki GR650 Tempters from the early Eighties. I hope so, because I’m in a quandary. I bought one, and it has aftermarket carbs and a K&N airbox instead of the stock carbs and air filter. It runs lean, but it’s in really great condition otherwise. I have thought about taking these carbs off and selling them and replacing them, but I’ve had trouble finding stock GR650 carbs in good condition. Have you ever heard about this kind of bike and what other carbs might work as a substitution for the stock carbs? I can block up the holes that go straight to the valves from the dirt bike carb, and it might be OK, but overall I’d just rather have a carb that’s a better match for this bike. — Jason Ritchie/via email 

A: I’ve not had one of these in the shop, so I had to do a little research to find what you were talking about. It seems Suzuki added a port to these bikes to swirl the air/fuel mixture as it entered the combustion chamber in an attempt to further atomize the fuel. The carburetors for your bike had an additional hose that conducted metered fuel to the swirl port. I doubt those carbs are easily found these days. You can probably close off the swirl ports and just use the main carburetor ports. I wonder if the previous owner made the change because of the difficulty in getting parts? I think if you block off the ports you’ll be fine. If you have the time and the patience, you can work on the jetting, if needed. Other than losing the original look, the bike should run fine if the carbs are correctly set up. MC