200 Johnson compression

[ckb5412]

I have a 1995 Johnson Oceanrunner. The powerhead was rebuilt 2 seasons ago and now has around 250 hours on it. What is considered good compression for this engine? It has 5 cylinders at 90psi and 1 at 110psi and runs good.

 

[Gary H NC]

Re: 200 Johnson compression

No pro but the 90 sounds a little on the low side.Did you test with engine up to running temp?
I was getting some 90's readings on my 81 model 175 until i warmed it up and retested.
Then it was all 105 to 110..
I'm not sure what the normal readings should be on that year engine.Dhadley or one of the other Johnny-Rude pros should chime in..

 

[JMO]

Re: 200 Johnson compression

Is this a looper motor if it is then 90 is pretty good these motors came from the factory witk 100 i did a lot of research on this because my 99 ocean runner was the same way but all were around 95 100

 

[luckyinkentucky]

Re: 200 Johnson compression

I don't know about the Oceanrunner, but I have a '94 200 Evinrude Vindicator, and it came from the factory around 105. I now have 5 on 100 and 1 on 95 on an engine that is 13 years old. From what I've seen those numbers are pretty consistent with other 200s in the same class.

 

[Monkaroo]

Re: 200 Johnson compression

One thing for sure . I would rather have 5 read alike and 1 read 20 pounds higher , than to have 5 read the alike and 1 read 20 pounds lower . The way I understand it is that even pressure between the cylinders is more important than actual pressure readings , as long as the readings are any where within reason . I think I would try what Gary said and get a warm reading for sure .

 

[luckyinkentucky]

Re: 200 Johnson compression

Another thing I remember from talking to my local Evinrude tech ....

For some reason Evinrude put the last cylinder a little lower than the rest for some reason. I can't exactly remember why, but I can ask if you need to know. He told me that it was something that he learned in Evinrude school about the last cylinder being off by 5 to 10 psi from the factory.