2G Bent valve?

[Honda hunter 1]

I,ve just took the compression from my dsm and cylinder no3 is at 125. I put some oil in the cylinder and took the compression and it still at 125 .I,ve just put that head on the car I purchased it from a freind, its ported and cammed hks 272 and the valves are over size ,if I have a bent valve would it affect my afpr? Cause they are off a lot they are at 37 40 afpr instead of 25,afp.

 

[NOSLO2PT0]

Bent valves affect compression of that cylinder, nothing to do with AFPR. You could have a bad valve stem seal, a valve not seating perfectly, or some slight piston ring damage that is dropping your compression. 125psi isn't too terribly bad. Anything lower than 100psi is when you start noticing some power loss.

 

[JacksonAuto]

If you do a leakdown test it will tell you where the compression is leaking from. I would bet you've got a valve that is not sealing or is bent. Was a valve job done on the head? Was the head ever transported with the camshafts installed? With the cams installed, there are always going to be valves that are open. These valves only need a slight bump to get bent. If you do a leakdown test and it does not show the valves or rings leaking, use a pressure tester to check your cooling system. This will tell you if the head gasket is not sealing or if you've got a cracked head.

You could have a bad valve stem seal,

Also for the record, a bad valve stem seal wont leak compression. The job of a valve stem seal is to stop oil from running down the valve stem and into the chamber. It has nothing to do with sealing the combustion chamber.


Things that lead to poor compression include;

Bent valve(s)
Contaminated valve seat not allowing the valve to close fully
Cracked piston rings
Cracked or otherwise broken piston
Head gasket seal
*Wrong gasket
*Improper installation/torque
*Warped head or block
*Improper surface finish for the gasket being used
Cracked head or block