Compression values ?

[chodie]

What should be the normal compression on the following motors:

CD-20R 1963 5.5HP

1985 6HP

All help is much appreciated.

 

[R.Johnson]

Re: Compression values ?

Depending on your guage, probably between 75-100 lbs. This is a figure that you really can't pin down,especially when dealing with these small engines.

 

[jbjennings]

Re: Compression values ?

Well, How much do you have?
I'd be hoping for about 80lbs., but I'm not totally sure on the 5.5's and 6's.
How close the cylinders are to each other is a good indication, usually. If one's quite a bit higher than the other, you have problems. I don't have any small motors that run right with more than a 10lb. difference.
Don't worry, someone will check in with the actual numbers on those, they're very common.
Good luck,
JBJ

 

[chodie]

Re: Compression values ?

The 5.5 HP has about 60psi on both cylinders.

The 6. HP has about 75 on both cylinders

 

[R.Johnson]

Re: Compression values ?

I would simply start them up, and see how they run, any problem, pull the cylinder head, and look. I doubt if you have a problem.

 

[JB]

Re: Compression values ?

Those numbers are acceptable because the two cylinders are close. That "spread" is what matters most. Not over 15% difference is what you need to worry about.