1966 CL 77 Compression Test

geosar · Post by **geosar** » Fri Dec 17, 2010 7:13 pm

I have a CL77 which has not run for over 25 years. From a former restoration false start, the carbs are off and the exhaust pipes are off. I have been spraying WD 40 for the past week and today I attached a compression gauge to each cylinder separately.

I cranked the kick starter until the compression reading topped out.

Then engine is cold. Right cylinder is 120 Left cylinder is 140.

Did I do any harm? Did this give me a usable reading and does it indicate I can leave the engine in place and reinstall peripherals to try to get it running.

Thank you very much.

George in Arizona.
CL77-1965,66,67

brewsky · Post by **brewsky** » Fri Dec 17, 2010 7:29 pm

Those are definitely good enough to get it running and see if there are other issues.

Ideally, the readings should be closer together, but they may settle in after some running time and the rings free up.

Goodysnap · Post by **Goodysnap** » Fri Dec 17, 2010 9:28 pm

Depending on how much WD was in the cylinders when you performed the test it may be a tad higher than a dry test. Good enough numbers to run at any rate. When you run your test make sure you have the plug out of the opposing cylinder and hold the throttle open.

geosar · Post by **geosar** » Fri Dec 17, 2010 10:24 pm

Thank you for the quick responses. I have no carburetors on the engine right now and I did have the opposite cylinder unplugged.

Thank you for the advice about the WD. I thought cycling the pistons dry might damage the cylinders.

Well, I will start the reassembly and try to get her running.

Again, thank you to everyone for the help.

George

Snakeoil · Post by **Snakeoil** » Sat Dec 18, 2010 10:41 am

You may want to pour a little Marvel Mystery oil down each plug hole and let it sit in there while you work on the bike. It will help free up the rings if they are stuck at all.

regards,
Rob

geosar · Post by **geosar** » Sat Dec 18, 2010 11:19 am

Already done. Thanks Rob.

Going to get the carbs on today and try to find a smaller jet for them.

George

Goodysnap · Post by **Goodysnap** » Sat Dec 18, 2010 12:40 pm

Snakeoil wrote:You may want to pour a little Marvel Mystery oil down each plug hole and let it sit in there while you work on the bike. It will help free up the rings if they are stuck at all.

regards,
Rob

I just used a mixture of 50/50 Marvel/ATF in my Saturn commuter SC1 w/ 180K on the clock. Suprisingly I could still see the cross hatching on the cylinders(with a video scope). Its seems to have cut the oil consumsion in half so far. Didnt bother checking compression as it was using a qt every 1000 mi. I'm not out much if it doesnt work.