So, my 1987 CR250 made 185 psi on a compression test as of last night. Pretty good, huh? Well, it made good compression but I could grab on to the flywheel and turn the motor over easily by hand. Last night, I put new rings in the bike and after a short ride this afternoon, it made 200 psi. Not that much higher, but the blow-by was so reduced I cannot turn the engine past TDC by hand at all. Now, it took something like 1.5 hours to get the bike started. It started within 5 kicks last night, I idled it for a few seconds, but had to shut it down as it was midnight. I had to pour a little gas in the spark plug hole to get it going it was so badly loaded up, I think I put too much oil on the piston before I installed it. The bike has a ton more midrange, I haven't run it much on the top end yet. It like to point the front wheel for the sky over the slightest of bumps.
The rings were so badly worn, the gaps were about 4-5 times what the new rings were. The moly band around the outside of the ring was so thin you could barely see it. All this and the motor still made 185 psi.
The rings were so badly worn, the gaps were about 4-5 times what the new rings were. The moly band around the outside of the ring was so thin you could barely see it. All this and the motor still made 185 psi.