Leaking BSA Lightning and Triumph Bonneville

Ready to take your classic queries: Tech Editor Keith Fellenstein.

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by Flickr/70_musclecar

Carb kits

Q: I have a 1981 Honda 750 Classic. I am having trouble finding carburetor repair kits. Are OEM kits still available? All of the dealers here in Ohio have closed. Any help would be appreciated.
John Walker/via email

A: You might try Matt Wiley at Moto-Vintage.net, as they sell K&L carburetor parts. Sirius Consolidated Inc. (siriusconinc.com), also sells kits for that year.

Throttle response

Q: Hi Keith, I enjoy reading your articles in Motorcycle Classics. I just got a modern Triumph T100 and I noticed the on/off throttle response at lower speeds is very “jerky.” I read up on this and it seems this is a common problem. There is a device called a booster plug which I have installed and it seems to help. Is there a better way to improve throttle response (i.e. ECU program). Thanks.
Bob Bentzinger/St. Louis, MO

A: Bob, there are a number of modifications you can make to your fuel injected T100. Triumphtwinpower.com has several options. Most of the mods require removal of some or all of the emissions controls and noise reduction systems on your bike so be sure to check local regulations before diving too deep. Speaking of deep, engine modifications is a deep rabbit hole. Once you get started it’s hard to stop chasing that last little bit of extra power. It helps to have a fat wallet.

Leaking BSA

Q: First, I want to thank you all for a great PAPER magazine. I love that it’s still coming to us all every other month IN THE MAIL. I have a 1970 BSA Lightning 650 with a 1969 engine in it. I have been told that there were many 1970 models sold with older engines, since BSA had leftover engines from the year before. My problem is that over the course of last winter, the bike was sitting in my heated garage and had been started approximately one year before. The bike had been sitting for about a year. One day I went out to the garage to leave for a ride on another bike, when I noticed a large pool of oil under the Lightning. It had all of a sudden, without any action on my part, leaked most of the oil out of the engine. It seemed to be coming from the oil screen/filter on the bottom of the engine. Is this something you have seen before? My plan is to drain all the rest of the fluids out of this bike, add fresh fluids and see if there is any leaking going on. Does that sound like a good plan, or should I do something else first? Any thoughts would be appreciated. I know, I should have ridden it, instead of hidden it.
Tom Sener/via email

A: First of all, thanks for subscribing. There is indeed something special about having a physical paper magazine to refer to. BSA 650 engines have a simple anti-drain ball valve in the oil pump outlet and it’s probable that it is open when it shouldn’t be. Oil then drained slowly through the pump and into the sump until it finds a way to leak out on your floor. Check the oil tank, I’ll bet you find it low or empty. Your best bet at this point is to drain the sump completely, then remove the plate at the bottom of the engine. Check the scavenge pipe ball valve, clean the coarse filter on the plate and clean all old gasket material off of the engine and the sump plate. Reassemble everything with new gaskets and possibly the gasket sealer you like best. The simplest gasket dressing is a smear of grease, and the worst you can use is RTV silicone. Somewhere in the middle is my favorite, blue Hylomar, now branded as Permatex 85420. It’s fuel and oil resistant and doesn’t dry out, making future inspection easier. If you intend to continue to store the bike, leave it empty of oil but write a note saying so on the bike for future reference.

Leaking Triumph

A reader offers another possibility for Joe Preston’s leaky pushrod tubes from my January/February 2022 column. — Keith

A: Regarding Joe Preston’s leaking Triumph Bonneville, I had the same issue with mine. After replacing the pushrod tube O-rings twice I finally discovered that the culprit was the O-ring that seals the exhaust tappet block to the cylinder. The hole the block is pressed into has very sharp edges so it’s almost impossible to install the block without damaging the O-ring. I carefully chamfered the edge of the hole and pressed the tappet block back in with a new O-ring and a little high temp sealer. Along with yet another set of the correct thickness tube seals the bike is now leak free.
Mike Jones/via email

Mechanic needed

And finally, a plea for a reader for a Triumph Trident mechanic in the Pacific Northwest. — Keith

Q: Good morning Keith, I find myself the owner of a 1969 Triumph Trident. I’m looking for a reputable mechanic, preferably in the Pacific Northwest, to go through the engine. Any thoughts or are you familiar with the triples?
Tom/via email

A: Tom, I own a 1974 Trident and do most of the mechanical work on it myself. Unfortunately I’m in Kansas so I can’t be of much help. Any Trident or Rocket III owners up there with helpful information for Tom?

Email questions and feedback to keithsgarage@motorcycleclassics.com or write: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609

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