86 150XP Compression Question

[otis44]

I've got a 1986 150XP, the compression #'s read 90lbs on all cylinders except one and it's 85. My question is I have half-heartedly tried to sell this engine. I'm not really sure if I want to or not. Are these #'s within spec or if not what should they be. The engine runs very strong and has never given any problems. Also the check I did was cold and removing one plug at a time. I have since read to do it warm and with all plugs removed. Would this make a difference. Thanks in advance for the help.

[Lockjaw]

That is about normal from what I have seen. You might see a little more with a warm engine.

[DoferGofer]

Those are the numbers I see with my XP . . . and I am keeping mine.

[otis44]

Thanks for the input, from what I had read in the past I thought the numbers were probably okay. The way the engine performs also indicates they are okay. Just curious what were the specs on this engine new. Thanks again

[DoferGofer]

I bought my engine new in 1985, have the original owners manual, bought OMC repair/overhaul manuals for this engine as well.

During all these years I have never seen any mention as to what the actual compression should be for this engine.

Some say no more than 10-15% difference. With compression numbers like you and I have on our engines. I worry more about the total timing and using good fuel.

I run my total timing at 28* BTDC. I know the sticker on the air silencer says 30* but, that was in the days when we had leaded gas.

With todays fuel and gasohol I dropped my back to 28* some folks drop theirs back to even 26*.

Good luck and enjoy your XP.

[Hookerz Tackle]

Them seem like good numbers. I just rebuilt my power head and on my old compression guage I am reading in the 80 - 85 range.

[DoferGofer]

Prior to your overhaul, what were your compression figures?


Regards,

[mountbkr]

My sis and bil are looking for one if you decide to sell IM me and Ill put you in touch with them. They are in Overton Co. Tn.

[ChampioNman]

I can have one ready in about 2 weeks total package or just PH just need a core.

[DoferGofer]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ChampioNman &raquo;</TD></TR><TR><TD CLASS="quote">I can have one ready in about 2 weeks total package or just PH just need a core. </TD></TR></TABLE>
Good afternoon my jovial and good natured friend who is always in a real good mood. I know that because the Bassmister told me so. Now that said and done and most of buttering you up is testing for results.
Since you overhaul these old crossflows, what are the most likely compression figures at the onset of an overhaul and what should one expect after the overhaul and then after breakend?