compression

[J Strickland]

Ok I have 49 Cub with compression readings of

CYLINDER 1 150
2 95
3 120
4 120

Mainly concerned with the 150 reading what is up?
Reading taken wet.

 

[rustred]

possibly carboned up.

 

[El Toro]

If you know anyone with a borescope light see if you can borrow it and look inside No1 cylinder. It may have a lot of carbon buildup. Hal

 

[edward will]

J. S
Try putting some alcohol in the cyl and put the plug back in. Let stand o/night then start engine. Let it run for some minutes and recheck compression. Ed Will

 

[rustred]

to get rid of carbon, run at a higher idle and add water to carb intake. can spray it in with a spray bottle.

 

[old]

The low one could be caused by sticking rings and the high one carbon build up. On both one simple way to clean is yep good old ATF in the cylinders. ATF will loosen up rings and also loosen up carbon

 

[mkirsch]

Inject Seafoam directly into the intake manifold through the vacuum port if your tractor has one. Otherwise, pull the air cleaner hose off and spritz it in through there.

You can get more into the engine through the vacuum port.

Run a 1/4 to 1/3 can in and then shut it off. Let it cool down overnight, then start it up again the next day. It'll smoke black for a while but hopefully that'll clean it up.

 

[gene bender]

Mite need to remove the side plate behing the carb so you can observe the valves to see if they are sticking or stuck. I had one similar to yours and it was sticking valves got them free and the readings evened out and then it ran just fine after the residue got all burned out. The tappet clearence could also be off a bunch never know just what you will find out in an old engine but the valves sure all need to open and close.