2S Compression Check w/o reeds & pipe?

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
I was doing a compression check today (as my bike is running poorly) and was suprised to see that the gauge was not registering any psi. 

kick, kick, kick =  0  :(

Bike is 2-stroke.  I have the pipe, carb and reed block off of the engine.  Should this make a difference?  I checked out the gauge on another bike and the gauge itself seems to work fine.  I did have the o-ring of the compression gauge seated down to the head.   I did not warm up the engine as i had critical items to make the engine run off of the bike (like the carb).

Is it ok to do the check with the reed block off?  I expected to at least get some reading.

Bike symptoms: very hard to start, no power, will not run at low rpm (dies).

fyi:  I've already read through many threads on compression checks via SEARCH but did not see an answer to my question.

Rings & gaskets are on order.
 
Last edited:

IrishEKU

A General PITA.
LIFETIME SPONSOR
Apr 21, 2002
3,806
0
]Is it ok to do the check with the reed block off?
Yup,

Seal the intake and exaust. Best guess is that you are leaking from one or the other. For the intake manifold I cut a pattern from a coffee can lid and used the boot coming from the carb to seat it to the block. You can do the same trick with the exaust too by cutting another piece placing it against the the cylender and putting the pipe back on. It's kind of "Shade Tree" I know but it works.
 

darringer

LIFETIME SPONSOR
Dec 2, 2001
1,029
0
There should still be compression. Once the piston closes the ports it should seal the combustion chamber. How does it feel when you kick it over? Any resisitance? Could be a broken ring(s) or even a hole in the piston crown.
 

jmics19067

LIFETIME SPONSOR
Jan 22, 2002
2,097
0
I dont think it should matter at kickstart speeds if you have the pipe and reed block off. You should be reading something. My guess is you either have a hole in the piston or the rings stuck bad
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
I agree - there should be some pressure.   There is only a little resistance when i kick it over.  I'll update you with what i find when i pull the cylinder head - probably tonight.
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
Well - the piston looked good.

As i was looking through the engine i noticed that the clutch shaft and flywheel/magneto shaft had some up/down&nbsp;play in them.&nbsp;&nbsp;<IMG alt="" src="http://www.dirtrider.net/forums3/images/smilies/frown.gif" border=0>&nbsp; I didn't want to run the engine in this condition so i crated it up and sent it off to Eric Gorr for a bottom end rebuild.&nbsp; I was expecting to have this done at the end of the season anyway.

Eric will look into the top end condition too while he has it.&nbsp; Now i guess i'll be able to get those things done around the house that i keep putting off as i will not have a bike to ride for the holiday week-end.

And another little thing i found (SEE PICTURE):
 

Attachments

  • kdx water pump case bearing.jpg
    kdx water pump case bearing.jpg
    65.9 KB · Views: 101
Top Bottom