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Hi. New poster. Just going through a 71 CB350-K3 making it roadworthy again. Fairly new at this but I have basic wrenching skills.
Right now I'm chasing low compression in the left cylinder; the right hits 135 psi stone cold easily on the kickstarter -- and the bike ran on that cylinder when I picked it up a few years ago -- so for now I'm calling that good. The left is very poor, I can kick it up to about 60 with effort.
- Set valve clearances and also just to be sure, tested with them loose to be sure they're closing. No change.
- Tested with a few ccs of 20w50 squirted in the plughole. No change.
- A few ounces of seafoam poured in the cylinder ... figured it can't hurt and might help with stuck rings ... did not drain out past the rings for several hours. Was finally gone the next morning.
So at this point I'm guessing the rings are sealing okay and it's more likely that it's valves or headgasket. I'm gonna have to pull the engine eventually but for my next test I'm thinking of pulling off the carbs and exhaust and just listening closely for air seeping out past one or the other valves while handcranking through the compression stroke with a socket on the alternator bolt. I don't know offhand if that actually works but it seems like a reasonable thing to try.
Any other ideas for narrowing it down? Thanks for any thoughts.
Right now I'm chasing low compression in the left cylinder; the right hits 135 psi stone cold easily on the kickstarter -- and the bike ran on that cylinder when I picked it up a few years ago -- so for now I'm calling that good. The left is very poor, I can kick it up to about 60 with effort.
- Set valve clearances and also just to be sure, tested with them loose to be sure they're closing. No change.
- Tested with a few ccs of 20w50 squirted in the plughole. No change.
- A few ounces of seafoam poured in the cylinder ... figured it can't hurt and might help with stuck rings ... did not drain out past the rings for several hours. Was finally gone the next morning.
So at this point I'm guessing the rings are sealing okay and it's more likely that it's valves or headgasket. I'm gonna have to pull the engine eventually but for my next test I'm thinking of pulling off the carbs and exhaust and just listening closely for air seeping out past one or the other valves while handcranking through the compression stroke with a socket on the alternator bolt. I don't know offhand if that actually works but it seems like a reasonable thing to try.
Any other ideas for narrowing it down? Thanks for any thoughts.
