Okay I did a search and I have learned alot about bikes on here. This is my first bike and I am pretty green on it actually it is my second bike but the first one (81 yz250) needs a piston and rings before it can be ridden. My 88 RM125 was "supposedly" rebuilt about 8-10 hours of riding ago but I am not able to get it running after quiting on my brother the other day while riding. It just chugged and quit and wouldn't start again. I did a comrpession test and I got 105 Psi and 140 psi after putting oil in the cylinder. shouldn't it spike higher than that with the oil in it? I also get a weird sorta of backfire but not a typical back fire after about 5 kicks and it sounds like a fluid "psst" sound not a regualr backfire sound. I am getting spark and I am getting fuel so I am to assume it is a compression problem. I am just wondering why after only 10 hours it might have a compression issue after a professional shop rebuild? Does it sound like I need new rings already? I was running 32:1 so I don't know why it would have worn that quickly and I don't ride hard at all. Do anyone have any specs for this motor or bike at all? (yes I know I need a service manual but I don't have one right at the moment! LOL!) Ran fine before it quit on us. Got it running again once and it went part way down the road before it just quit again and will not start again after many many kicks.
P.S. yes I did do the test properly with the kill switch pressed and the throttle wide open
P.S. yes I did do the test properly with the kill switch pressed and the throttle wide open