Acceptable compression for a 1989 force 125?

[bunder]

What is the lowest compression that would be considered acceptable for a 1989 Force 125? The third mechanic I've had look at this thing said the cylinders are around 117 across the board and that's why it won't run over 2500 rpm. I checked the compression my self and verified it at 117 it comes up to 122 after squirting some oil into the cylinders. The manual gives a range of 125 to 145. Is it possible that 117 is bad enough to keep this thing from running over 2500, or is this guy just trying to sell the rebuild?<br /><br />Any advice would be appreciated.<br /><br />Bob[*]null

 

[clanton]

Re: Acceptable compression for a 1989 force 125?

Try a can of engine tuner/deep creep, it will clean the carbon out of the engine. I would think that you may have other problems. What is the ignition system doing at 2500 rpms?

 

[ozarkjeep]

Re: Acceptable compression for a 1989 force 125?

My 50hp Force engine has no problem revving past 2500 RPM and its got about 70 psi in each cylinder<br /><br />I havent had time to decarb it yet

 

[ODDD1]

Re: Acceptable compression for a 1989 force 125?

Bunder, compression like this will NOT CAUSE YOUR PROBLEM...when compression drops, the first signs are hard starting, stalling in gear, a weak, lazy idle quality.......you will lose some top end, but NOT what you are talkin about....dont get me wrong, 117 aint too good,the rings are definatly getting stuck in the ring grooves, but you have enough that it should function reasonably well at high speed....your tech's should be lookin for additional prob's.....

 

[sony2001]

Re: Acceptable compression for a 1989 force 125?

bunder change mechanic and fast. Your runnig on 3 cylinders not 4. Most likely one of the two CD units {SWITCHBOX} has failed for that<br />cylinder. Decarbonize that cylinder at 117 lbs. It may not be the one not working!

 

[bunder]

Re: Acceptable compression for a 1989 force 125?

I checked each plug wire while running at 2450 rpm while it's cutting out and I don't see any drop on the plug wire. I've pulled each plug while it's running and they all drop about the same. at 2400 it starts to cut out and at 2500 it falls flat on its face and stalls. It starts immediatly after it stalls so I don't think it's fuel starved. Can anyone think of anything else I can check?<br /><br />Thanks

 

[sony2001]

Re: Acceptable compression for a 1989 force 125?

bunder since all cylinders are cutting out you may have a shorting wire. When the timing advances the assembly may ground on something. OR a problem with the trigger housing or stator. If shorting test for spark at full throttle........!

 

[12Footer]

Re: Acceptable compression for a 1989 force 125?

He might have measured it with a "dealer's gauge", meaning perhaps, the gauge is readin low. I would be more concerned with the "across the board" statement...As long as the compression was equal in all cylinders (or close to it), I would dissmis it as a well-worn engine, but not a dead one.<br /><br />Do the decarb thing, re-check the compression,and you might be pleasantly suprised.

 

[sony2001]

Re: Acceptable compression for a 1989 force 125?

Oh bunder! Do a number of decarbonizings. The previous owner could of never done it. Your Force new is 145 to 165 psi. Hang in!