My 1994 85HP yanmaha is running rough between 2000 and 4000rpm. idles good and run smooth at 4000+. I have changed spark plus, cleaned carbs, new fuel filter and checked coils. Compression is 100, 100 and 95psi. Is the one cylinder compression off far enough to cause this? Any ideas?
no
you have either a spark or fuel issue
what was it doing before you cleaned teh carbs, and how did you clean them?
It was running rough before I cleaned the carbs. I took each one complettely apart and cleaner with carb cleaner - did not see any signs of build up on any of them. There was no change to performance after this. Could I have a bad coil? How do I check this with an ohm meter?
you can ohm test with a multi meter, but you cant do any real output tests without a DVA meter
have done a drop cylinder test?
Not trying to hijack thread, but Chris V check your pm. Thanks
Tried the drop cylinder test today and determined that the #3 cylinder is the problem. This is the one with the lowest compression. Swapped coils and eliminated the coil as a problem. I suspect the problem is still in the carb. Any thoughts?