what should compression be on a 1991 120 hp evinrude?

[caldog101]

just bought the boat and motor at a good price.the motor has not run in about 8 months,The motor started right up this morning,the motor is a 1991 120 hp evinrude it is in good shape and i am going to do a compression check,i would like to know what a good pressure should be and i know they should be close to 15 % of each other i also own a 1991 90 hp v4 crossflow is the 120 hp a loop and what is the big difference between the 2? also are the 120 a good motor ?

 

[DHPMARINE]

Re: what should compression be on a 1991 120 hp evinrude?

Maybe if you told us what readings you have,we could help you better.<br /><br />DHP

 

[Dhadley]

Re: what should compression be on a 1991 120 hp evinrude?

As long as the compression is within 15 lbs (not %) of high to low you're OK. One side may be even but slightly higher than the other side, that's OK too.<br /><br />The difference between a V4 crossflow and a V4 looper? Night and day. The looper is a torque monster. <br /><br />Clean the carbs before you stick it in the water. Use only Champion plugs, and set it up as close to 6000 rpm with an average load as you can.

 

[caldog101]

Re: what should compression be on a 1991 120 hp evinrude?

Well guy's did a compression check today and the numbers are standing behind the motor looking at it<br /> 122 128<br /> V4<br /> 125 125<br />Dhadley the motor was not run for about 8 months had to squirt a little 2 cycle gas mixture in the carbs and it fired up.I let it run for about 4 minutes and it idled good and accelerated fine but i noticed the the port side was a little hotter "i put my hand on both sides of the block "the second time i started it was today for the comprssion test ,it started fine with no need to squirt carbs let it run for about 4 minutes to warm it up again the same side felt hotter to the touch of hand.the tell tale is pissing water real good and it is not hot at all.i am wondering what my next step should be thanks for your help

 

[Solittle]

Re: what should compression be on a 1991 120 hp evinrude?

With any engine that is new to you it is a good idea to replace the water pump, thermostats, spark plugs and gear case oil. Test the overheat alarm while you are at it. Your compression is as good as it gets.<br /><br />We are off to Elliot tomorrow.