Topic: Two Stroke ? Right Side Hotter than Left, Bridgestone 350

[Popwood]

Bringing this bike back to life. Running, but not perfect. New to 2 strokes, but have been reading a lot about them.

This 1967 GTO model is running now after 15 years sitting, and was likely sitting for a long time before that. Given that, it’s been under roof all that time and is in remarkably good shape considering age. Less than 5,000 miles on the clock.

I’ve thoroughly cleaned carbs, synced them, checked timing, points gap, condensers. New, appropriate plugs. Since both tires are flat can’t ride yet but have started it several times and run for a few minutes so it’s thoroughly warmed up.

Today I noticed the right side pipe is notably warmer/hotter than the left. Both headers are hot, and I’m pretty sure both cylinders are firing. Plugs would suggest this is so. Roughly, I’d say right is twice as hot as left feeling along the length of the mufflers. The air exiting the right pipe is warm, air on the left seems a bit cool, call it room temp.

I’d say there is more smoke coming out the right pipe compared to left. This bike is equipped with an early model that introduced oil injection rather than mixing oil and gas. I’ve checked the oil pump and made slight adjustment and it seems to be working.

So, sorry for the long background, but wondering if anyone has thoughts about why one side is running hotter than the other. Appreciate any feedback.

Thanks.

[ekpent]

Only thing I can add is that on Yamaha and Kaw triples and probably Suzuki's is that if a particular cylinder is smoking more then the rest it could be a sign of a bad crank seal.I cannot right now name which pipe per model is a potential clue without looking it up.
  Also not saying that is your problem but more oil could cause it to be cooler or the carbs are not metering the same. If you google there are some tests I believe that can be done to see if crank seals are shot.

[Popwood]

Steve-O warned in an early post when I started work on this that crank seals are frequently a problem. Think I also read that a seal in the transmission could also leak into the engine, but I may be remembering wrong. Regardless, I’ll look into the crank seal, twice warned and all. Thanks.

[craz1]

Im assuming it has one cable which splits into two. Check and make sure the slides are raising together

[Popwood]

Yes, carb slides synced. But if they weren’t, would it cause heat difference or just smoking difference?

[craz1]

It would have to way out of sync

[Stev-o]

Steve-O warned in an early post when I started work on this that crank seals are frequently a problem.

Highly suggest doing a leak down test.  Here is a pretty good DIY article...

https://www.diymotofix.com/blog/how-to-do-a-diy-two-stroke-leak-down-test

And video...

Or you can buy an expensive one...

https://www.revzilla.com/motorcycle/motion-pro-2-stroke-leak-down-tester?gclid=CjwKCAjwjZmTBhB4EiwAynRmDy1SCQOSvDXEc5egZ-w4_8Qpeh0juFtWtHsJB2j0iGQ1DXjJ2O9tlhoCpcYQAvD_BwE&sku_id=173784

I was lucky, my buddy had one that we used.  My Kaw H1 had bad crank seals and burned a hole in the piston.  Did an expensive engine rebuild [crank rebuild w/new seals, cylinder bore and new pistons/rings] and it has run great ever since.

[MrGardman]

I would have to agree about the crank seal being the cause of your issue.