Compression test results


13 replies to this topic
  • zimak

Posted February 05, 2008 - 02:15 PM

#1

Decompressor pulled: 0lbs
Decompressor not pulled: 120lbs

Where to start?

  • pwrpapa

Posted February 05, 2008 - 02:50 PM

#2

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.

  • Maroast

Posted February 05, 2008 - 03:12 PM

#3

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!

  • martinfan30

Posted February 05, 2008 - 03:21 PM

#4

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

  • zimak

Posted February 05, 2008 - 03:27 PM

#5

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.

  • zimak

Posted February 05, 2008 - 04:41 PM

#6

Ok tried the wet/dry test.

No change. Guess its time for some valve work.

  • zimak

Posted February 05, 2008 - 04:49 PM

#7

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

Rather confused here.

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  • martinfan30

Posted February 05, 2008 - 05:19 PM

#8

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.

  • zimak

Posted February 05, 2008 - 05:21 PM

#9

Runs smooth and starts easy, garbage for power.

  • zimak

Posted February 05, 2008 - 05:21 PM

#10

BTW Manual says I should be seeing:
Decompressor pulled: 89lbs
Decompressor not pulled: 160lbs

  • martinfan30

Posted February 05, 2008 - 05:25 PM

#11

BTW Manual says I should be seeing:
Decompressor pulled: 89lbs
Decompressor not pulled: 160lbs


Check my edit above.

  • zimak

Posted February 05, 2008 - 06:29 PM

#12

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

  • creeky

Posted February 05, 2008 - 07:08 PM

#13

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??

  • zimak

Posted February 05, 2008 - 07:58 PM

#14

I should give it a shot then huh?





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