rpm's on 225 evinrude

[sandy151]

Help! I have a 1997 evinrude 225 ocean pro that I can't get over 4500 rpms. I have rebuilt just about everything including the carbs, and just replaced the stader. Power pack looks good and throttle is good<br /> ...any ideas?

 

[ob15]

Re: rpm's on 225 evinrude

Were you ever able to get more than 4500? If so what was it?<br /><br />Edit: I noticed another post about the motor overheated. Something from that could be causing the problem.

 

[andy6374]

Re: rpm's on 225 evinrude

Are you sure you are getting spark on all cylinders? <br /><br />All the ignition coils have a good ground? This is a classic.

 

[sandy151]

Re: rpm's on 225 evinrude

The motor used to get to 5500 rpm. Going to take it out in a bit and use the timing light to see if we are getting spark on all cylinders. Any other thoughts?

 

[ob15]

Re: rpm's on 225 evinrude

How does the motor sound? Have you checked the compression? <br /><br />Once the problems gets figured out & get your rpm's back to where they were, we'll have to work on your setup to get the rpms up a little higher than 5500. But that's a totally different post in the prop section.

 

[sandy151]

Re: rpm's on 225 evinrude

The compression was good on all but one cylinder which was only slightly low...not enough to cause a problem. Tried a 15.5 prop, but actually ran better with the 17" prop we had on it. Motor sounds good and idles fine.

 

[ob15]

Re: rpm's on 225 evinrude

Do you know what the numbers were?

 

[Dhadley]

Re: rpm's on 225 evinrude

Ditto. Describe "slightly low".

 

[sandy151]

Re: rpm's on 225 evinrude

5 cylinders are at 115. The low one is at 90. All cylinders are firing.

 

[ob15]

Re: rpm's on 225 evinrude

I suspect that is why you only can get the rpm's you mention. something is not right. Because the motor overheated, I think it would be wise to pull the head and have a look at the cylinder with low compression. Should probably try to figure out why it overheated to prevent that in the future.<br /><br />This is time for the experts to chime in and help out.

 

[TxShorty]

Re: rpm's on 225 evinrude

Standard accepted compression deviance is 10% from highest to lowest. I'd be willing to bet you have some scoring in the low cylinder, and this is the cause of your lowered RPM's. It's definitely time to pull the head and see what's going on.

 

[sandy151]

Re: rpm's on 225 evinrude

Pulled the head and there is some scoring, but very slight. I suspected that this might be part of the problem, but did not think that it would cause such a marked decline in the performance. If 10% is accepted then I am thinking that my 25% in that one head is an issue. Thank you for all of your help.