Real world compression numbers?

New to me 1988 250 XC starts and runs ok. No apparent lack of power. Measured compression while spinning the crank with a power drill and got only 40 psi. Cold and dry. Shot some oil in and compression improved to 60 psi. Still way less than I would expect. It may be that my old compression gauge is whacko, which I need to figure a way to test, or maybe my ring is toast.

So, with a good gauge, what kind of psi numbers are people seeing normally?

If the bike has been sitting for some time or stored away most likely the ring is just stuck in the piston ring land from dried up carbon or oil. I can't say what is a good compression reading is for that model of Husky but yes it should be considerably more than 40-60psi.

Marty

Don't have any experience working on the 80's stuff but I can say for certain that a fresh rebuilt early 70's 450 runs 130 psi when turning it over with the kicker.

Thanks guys. That was my hunch too. I’ll double check it since the readings were before I got it running and if it hasn’t improved greatly, and my gauge is believable, I’ll look into the top end. Maybe just a disassembly, clean-up of the ring groove, check for excess wear, and reassembly will get me back in business.

If it runs... compression is not likely to be a true 40-60psi. Doubt you could get it started with that little compression. And it would feel very soft at the kick lever.

On the other hand, It could have been stuck and/or rusty in there, and once running it has cleaned itself out to some degree. That's obviously not the 'best' way to rebuild a top end! But I've seen it.

Try pushing it down the street in second gear for about 50 feet with the gauge attached to get a better number

Got to have the throttle wide open and kick until the gauge stops going up. Usually no more than 6 or 8 kicks does it.

87-88 250 are around 200 psi with a healthy motor...earlier 250 are 160-180..

It would not run with 40 psi . Did you have the throttle open ?