Compression test results

Decompressor pulled: 0lbs

Decompressor not pulled: 120lbs

Where to start?

that's a little low. put some oil in the plug hole an see what you get then.

if it goes up it's rings, if it stays the same it's valves.

that's a little low. put some oil in the plug hole an see what you get then.

if it goes up it's rings, if it stays the same it's valves.

Very interesting...cool tip, thanks!

Ya, referred to as "Wet and Dry compression tests".

Ok gonna give that a shot. This is just confusing the hell out of me.

I get no smoke and dont eat a drop of oil. My valves are spot on for clearance (although they were at 0 for a while from the PO).

Plug looks good.

Jetting should be damn near perfect according to the charts.

Starts first / second kick hot or cold but just runs like crap.

Wont even consider lifting the wheel in first.

Ok tried the wet/dry test.

No change. Guess its time for some valve work.

Any guess as to why I'm getting 0 with the decompressor pulled in but 120 with it out?

Rather confused here.

Is it misfiring, or runs smooth but down on power?

A cylinder leakdown test may be in order here. What this will do is after pressurizing the cylinder with air pressure, you will know where you are losing compression. Here it in the exhaust=exhaust valves. Hear in the air cleaner=Intake valves. Hear it through any opening in the case=rings. Air bubbles in coolant=head gasket/or crack some where.

You will have to set it at compression TDC and hold the crank to keep the air from pushing the piston down.

Runs smooth and starts easy, garbage for power.

BTW Manual says I should be seeing:

Decompressor pulled: 89lbs

Decompressor not pulled: 160lbs

BTW Manual says I should be seeing:

Decompressor pulled: 89lbs

Decompressor not pulled: 160lbs

Check my edit above.

Here is a weird one.

Manual says during valve clearance check.

Intake: .15mm

Exhaust: .20mm

However during Compression check part of the manual it says that QFT:

"If compression is not within specification, recheck the following.

Loosen the exhaust valve lock nut and adjust the exhaust valve to a valve clearance of approximately 1mm (0.04in).

Warm up the engine.

Stop the engine and recheck the compression."

....should I seriously redo my valve clearance from .20mm to 1mm and try to run it?

pg 8-4 of the manual btw

Here is a weird one.

Manual says during valve clearance check.

Intake: .15mm

Exhaust: .20mm

However during Compression check part of the manual it says that QFT:

"If compression is not within specification, recheck the following.

Loosen the exhaust valve lock nut and adjust the exhaust valve to a valve clearance of approximately 1mm (0.04in).

Warm up the engine.

Stop the engine and recheck the compression."

....should I seriously redo my valve clearance from .20mm to 1mm and try to run it?

pg 8-4 of the manual btw

I think that this procedure is to ensure that the auto decompressor is not causing a low compression reading??

I should give it a shot then huh?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now