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

Trickle Charger Question

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.

Trickle charger

Q: I have recently obtained a 1970 BSA A65T Thunderbolt with a 12-volt positive ground system. I would like to keep a trickle charger on it if possible. No fancy lithium batteries here, just a plain old sealed unit. The gentleman who owned it previously had a pigtail connected to the battery for a trickle charger. He explained that the positive connection on the charger went to the grounded, positive side of the battery, while the negative side went to the, well, negative side of the battery, which is not grounded. When I connect my Battery Tender to it, the indicator light says that the charger is incorrectly connected and so it won’t charge. How can I correct this situation? If it matters, I have a Boyer ignition system. — Doug Stobbs/via email

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A: Check to make sure you really have positive from the charger going to positive at the battery. I suspect it’s not. Most charger pigtails have a fuse in the positive/hot line as most vehicles are negative ground. This will confirm which is the positive line. Even though your BSA is positive ground, the fused or positive lead from the charger should still go to the positive side of the battery. In other words, ignore the fact you have a positive ground system. My unsolicited advice is to not leave the tender connected all the time, just connect it as needed, say once a week or month, and remove it once it shows the battery is fully charged.

Lithium Batteries and Chargers

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.

Lithium batteries and chargers

Q: In your January/February 2017 column you mention that lithium batteries last longer maintained by special lithium chargers. Why? If special chargers are needed, maybe lithium batteries are not viable in our bikes with their non-specialized charging systems? And what is the life expectancy of the lithium battery? — Cliff Elkins/via email

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A: The chargers are designed to meet the requirements of lithium batteries. A single lead-acid cell develops higher resistance as it charges, while a lithium cell develops lower resistance as it charges. Lead-acid batteries self balance as each cell reaches capacity, while lithium batteries trend toward short circuit. A battery management system reads the individual cell charge state and directs charging voltage to the cells at a lower charge state. If your charging system produces between 14 and 15 volts at running rpms and if your battery has a built-in management system, a lithium battery should be fine. Battery chargers that have de-sulphation circuits should never be used with lithium batteries. Modern lead-acid battery chargers can be used, but should be monitored and disconnected once they indicate the battery is charged. Shorai says that their batteries have the same charging requirements as AGM batteries, but recommend their charger for the reasons laid out above. Shorai warrants their batteries for 5 years.

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.