Low Compression

[Monte1961]

Re: Low Compression

what are you experiencing now? Did you retest compression? If so did you get same results? Please elaborate!! also model # would be a good thing for us to have. post back.

 

[speterson1011]

Re: Low Compression

J90PLSIF is my model #. After putting it back together im still getting the same compression on all cylinders. All the cylinders look great even the one with low compression. All rings are good and cyl walls are good

 

[Monte1961]

Re: Low Compression

speterson1011. So what was/is the engine doing besides running like sh*t? We might be chasing a rabbit in a rabbit hole. With your old compression readings, I do see a 20% drop in compression readings witch tells me even after replacing cooper rings on cylinders and not changing anything, you might have to face the possibility doing minor/major overhaul. My only thought at this point is, If engine has sufficient fuel supply, timing is good and has good spark, do a link & sync and make it run the best you can. Look in to the fall for tear-down and major overhaul. Well that is in case you get lucky and find something really profound. Good luck and post back let us know.

 

[speterson1011]

Re: Low Compression

When I have it at 3/4 or full throttle it skips which im assuming is the water being mixed in the cyl causing this. about 1/2 throttle and lower speeds it runs great. Smooth and never misses a beat. I'm going to start tearing it apart today looking for problems

 

[Monte1961]

Re: Low Compression

When I have it at 3/4 or full throttle it skips which im assuming is the water being mixed in the cyl causing this. about 1/2 throttle and lower speeds it runs great. Smooth and never misses a beat. I'm going to start tearing it apart today looking for problems

Before tearing it down after reading your last post, what your describing a lean condition at 1/2 throttle and above. When was the last time the carb/s were overhauled? I would almost bet the high speed carb circuit/s are plugged up!!! If you have no idea when they were last overhauled, you might want to think about it?! Even if you do have to overhaul engine, you will know carb/s will be fresh. Overhaul carb/s with OEM kit/s, do a link and sync. You might just get lucky! Good luck and post back.

 

[jbjennings]

Re: Low Compression

Before tearing it down after reading your last post, what your describing a lean condition at 1/2 throttle and above. When was the last time the carb/s were overhauled? I would almost bet the high speed carb circuit/s are plugged up!!! If you have no idea when they were last overhauled, you might want to think about it?! Even if you do have to overhaul engine, you will know carb/s will be fresh. Overhaul carb/s with OEM kit/s, do a link and sync. You might just get lucky! Good luck and post back.

I would heed the above advice. Figure out what the problem is with your motor. Even with the one cylinder a little low on compression, I'm still betting it will seem to run fine when you get the problem fixed. You may still consider rebuilding it in order to keep the motor in good balance, but if it were mine I'd want the problem with it figured out before I rebuilt it and ruined it first time out due to a dirty carb or misadjusted spark advance or whatever.
Good luck,
JBJ

 

[perron582]

Re: Low Compression

just wondering what a link and sync is?