Too much compression?

[Geoff Smith321]

Hi Ya my friends, I checked the compression on my Johnson VRO 70hp circa 1990 and found the following figures:- No 1= 145psi<br /> No 2= 145psi<br /> No 3= 142psi<br />The difference in No 3 could be down to the fact that the engine had been running with No 3 main jet partially blocked. The readings were taken with engine cold.<br />Would you consider these excessive as when reading other posts on the subject I have yet to see anything as high as these.<br />Thank you.<br /> Geoff.

 

[R.Johnson]

Re: Too much compression?

If you were to check with a different guage, you could well find the readings' 10-15 lbs. lower. These guages work fine for making a comparison test between cylinders, but I don't think I have ever seen two guages in agreement when it comes to the lbs. reading.

 

[umblecumbuz]

Re: Too much compression?

Your cylinder by cylinder readings are very close. <br /><br />To me, that's a better sign of a healthy engine than the actual compression figures. These testers can be way out. Try another, and you'll probably get different pressures.<br /><br />Go and fish huh?

 

[Geoff Smith321]

Re: Too much compression?

Thank you gentlemen, as you will probably gather I am a newbie at this engine repair lark but your assistance along with the rest of the posters will give me the confidence to try some repairs myself.<br /><br />Tight Lines.

 

[G DANE]

Re: Too much compression?

I have a two cylinder looper 1988 which has 148 in both cylinders. I think they were about 150 new.

 

[Chinewalker]

Re: Too much compression?

Sounds good to me - my 75hp Johnson triple punches my own gauge a shade over 140 with about a 2psi variance...<br />- Scott