Very low compression, what to look for?

deafanddiabetic · Post by **deafanddiabetic** » Thu Jul 24, 2014 1:40 pm

Many many thanks to Loud Mouse for help bringing my project back to life. The frame came back from paint last weekend and I can now install the engine happily and get started on rewiring. Much appreciated.

LOUD MOUSE · Post by **LOUD MOUSE** » Thu Jul 24, 2014 3:15 pm

Ben and I fixed his "0" compression problem.
I saw that earlier in the discussion he had the engine apart.
Anyone have an idea where a person who is working on his first C/CB/CL72/77 engine may have a "0" compression problem!
I directed him (nice feller ya know) and as we talked he corrected the problem.
Good on ya Ben.
Call anytime you need advice. ...............lm

LOUD MOUSE wrote:I would like to be of help.
Please call me at 830-895-0654 when you can be at the engine or give me your number and I'll call you. ...............lm

deafanddiabetic wrote:Well, I'm still registering zeros on both cylinders with my compression tester. It sucks and blows my finger over the spark hole but I don't know where to look next.

I've adjusted the valves several times, turn the crank to the "T" mark, feel for the looser rocker arms, adjust those to be .1", then turn the crank 360 degrees to the "T" mark again and adjust the other side valves to the same. Then after a few kicks, I notice both intake valves are closed and only one exhaust valve is closed. Am I overlooking something stupid? Maybe my tester is not working anymore? Feeling pretty frustrated.

G3 · Post by G3 » Thu Jul 24, 2014 10:37 pm

D&D; Bet your one uhhappy guy now!
On behalf of those who know...thanks Ed for once again personalizing your service. Awesome.

mike1969 · Post by **mike1969** » Fri Jul 25, 2014 6:12 pm

So what turned out to be the problem?

deafanddiabetic · Post by **deafanddiabetic** » Sat Jul 26, 2014 4:28 pm

mike1969 wrote:So what turned out to be the problem?

Specifically, I'd installed my cam chain with the camshaft positioned incorrectly. There was a very light mark in my camshaft end (where the points are) that needed to be sanded to find, then I put the crank at the "T" mark, had the mark on the cam end and the sprocket straight up together, then replaced the cam chain on it, then the valves all ran exactly as they were supposed to and I went from 0psi in both chambers to 100~ dry on each!

mike1969 · Post by **mike1969** » Sat Jul 26, 2014 5:58 pm

D&D, Thanks for sharing that with us. It seems we learn more from mistakes than by doing things right.
LM helped me out if a jam with my Dream around 4 years ago. I put my engine back together about 5 years after taking it apart and forgot the oil control head cover plate which gave me very serious blowby. I had the motor out and apart at least 7 or 8 times. LM solved the problem and bike was perfect after that. Mike

deafanddiabetic · Post by **deafanddiabetic** » Sat Aug 16, 2014 12:13 am

So, finally got the bike all put together after paint and rewiring the harness, carb and tank on, set the ignition timing, put fresh oil in it and still had about 100psi in both cylinders.

I tried to kick it over a few times, I got it to idle and stay running for a few seconds and then died. I tried several more times, playing with the choke and carb screws but never got it to stay running more than a few seconds and it sounded pretty rough.

Next, oil starts dumping out of the flange around the left exhaust header. I decided to call it a night, but first I checked compression again. 90 in the left cylinder, 60 in the right. Sigh.

Tomorrow I'll attack the valve clearances again and see if anything changed as it's "settling in" after new rings, valve job, etc.

Anything I might be overlooking? (Besides needing to readjust and tighten the exhaust header to the body better)

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Very low compression, what to look for?

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