Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => 350 Talk => Topic started by: Puchman66 on October 07, 2010, 06:07:20 PM
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I did a compression test on my 350 recently after taking it for a ride and this is what I found.
L-95 / R-90
I squirted a little oil in the cylinders and it brought each up about 5 psi
What do you think?
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Your compression is way low, should be around 150lbs each, take the top end off and see if rings are stuck, if not and the cylinders look good, get a new set of pistons and rings, Richard owner of this site has them in stock at low prices
Jeff Bar
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For what it's worth, Here's the text from page 72 of the 350 shop manual:
Standard : 8.5–9.5 kg/cm2 (121-135 lbs/in2)
Permissible Limit : 6.3 kg/cm2 (90 lbs/in2)
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Hi Puchman66
Question.
When you did the compression test did you have the throttle wide- open!
If so i agree with Jeff get new pistons and rings from Richard that's if the
cylinders are OK.
Thanks.
Reed.
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I'll check it again with the throttle open.
Thanks for your input guys.
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For sure.... check it with the throttle open.
If your readings are still low, squirt some oil in the cylinder and test it again. The oil acts as a sealer and will temporarily boost compression. If that works and your compression improves, that is a clue that your rings may be stuck or your cylinders are worn. Since you have no valves in the top end, you don't have to worry about problems there.
I have had several two stroke motors come down with stuck rings. Apparently the two stroke oil that is added to the gas carbons the rings up. Also, since the rings can't rotate, (there is a peg at the ring gap that keeps them from rotating in the grooves) they may not be able to keep clean as well as a four stroke motor.
The good news is that this is a relatively easy fix on a two stroke.