Couple of questions...post-rebuild

[Reggie08]

Just fired up my motor for the first time since finishing a complete rebuild and had a couple of questions. The motor is an 85 'Rude 90hp

Checked the compression first and and the #1, 2 and 4 cylinders were 135-145psi. The #3 however is about 100psi But the #3 is also bored .040 over while the other three are .030 over. Could the larger cylinder cause the lower compression? Are there over-size rings I can use on that piston to bring the compression up?

Also, when she fired up she took off on me. I don't have it on the boat right now so I couldn't tell you what the rpm's were. But how do I properly adjust the idle on it? I'm going to study the manual and try to do a link-n-sync but I'm wondering if that should be done with the control cables disconnected? Is there a base setting I need to set everything at?

 

[Faztbullet]

Re: Couple of questions...post-rebuild

Hey Reggie, Make sure timer base and throttle arm are toward rear of engine, and check your pick up linkage on carb cam. GO BY THE BOOK!! That .040 piston should have came with matching rings. Also compression will change as rings break in, Give it about 5 hrs of break in @ 1500rpm then recheck compression. Any readings before starting will be off as some cylinders may have more oil coating and higher readings.

 

[Reggie08]

Re: Couple of questions...post-rebuild

Sounds good FB. I checked the compression before I even turned the key so those numbers may be very skewed. I figured I re-check the compression after the break-in period was over.

I found a picture I took of the motor prior to any disassembly so I'm going to reset everything back to that point since that's where the motor was setup at prior to the piston getting damaged. I'm thinking/hoping that will give me a good starting point.