what should compression be on 1991 60HP Johnson 3 cylinder

[twierz]

2 cylinders at 125 psi...1 cylinder at 135 psi. What should they be at? Could the mismatch cause me problems? Mechanic didnt think so. Thanks

 

[Greg22]

Re: what should compression be on 1991 60HP Johnson 3 cylinder

Hi Tim J,<br /><br />The rule is all cylinders should be +/-10% of each other, therefore your motor is ok.

 

[clanton]

Re: what should compression be on 1991 60HP Johnson 3 cylinder

I would insure service bulletin SB2221 temp sensor, SB2225 thermostat seat, SB2271 jet, timimg kit, SB 2276R1 relocated tattle tale nipple,and waterpump kit 432955 has been installed. The waterpump kit has different impeller and pressure relief spring and cover.

 

[Dhadley]

Re: what should compression be on 1991 60HP Johnson 3 cylinder

Those motors tend to run lean in the mid range - especially on #2 - so be careful. Use Champion plugs and FRESH 87 octane. If you do a lot of extended running in the mid range it wouldnt hurt to richen up the mid range jets some. Prop it out at 6000 with an average load so as not to stress it. <br /><br />All of the upgrades clanton mentioned are a must.<br /><br />Good luck!

 

[G DANE]

Re: what should compression be on 1991 60HP Johnson 3 cylinder

Hi timj<br /><br />Its hard to tell normal compression as different gauges often come out with different readings. However most of these motors in good condition will show compression figures somewhere between 125 and 150. In my experience 130 is very common. Usually it will run well if they are just above 100 and within 10%. The performance will drop as wear lowers compression.

 

[JB]

Re: what should compression be on 1991 60HP Johnson 3 cylinder

TimJ.<br /><br />Go to Roscoe's post "Messed up post??".<br /><br />This is a perfect example of the confusion you cause readers when you start a new topic in the middle of an exchange on your original post.<br /><br />Please keep all questions and replies on one engine problem in one topic.<br /><br />Thanks.