valve clearance correct and still low compression ?!?!?!?

alright i have my dads 2004 Suzuki rmz 250 that will not start and feels like very low compression.since the bike is not mine and myself being a 2 stroke guy i think I'm overlooking something or lack the knowledge lol. so roughly 2 years ago the bike had a new top end and valve adjustment. the 04s have a real problem with valves it seems like from what iv read and this one being no different has been shimmed and new valves installed at a shop. this was my first time adjusting the valves and i thought i did everything correctly. right now the valves have a intake clearance of .007 and exhaust valve clearance of .007. before i shimmed the intake valves the right valve was at .005 and the left was zeroed out. i did not touch the exhaust valves. so I'm not sure if i didn't get the timing marks correct or what because it feels like i have less compression then im kinda stumped as to look next. keep in mind this is my dads bike and hes 50 ,only trail rides, and is not hitting the rev limiter!!


thanks guys any input is welcome !!!!

Count even number of teeth to the marks that line up on top of head on each side. If you do have timing correct, Think about it. When you have low compression in a 2 stroke what causes that condition? Well you would be right if you said you got bad rings. 2 strokes and 4 strokes have piston rings. When they go bad compression drops. Valves can also create this condition. However, if your valves are in spec then it's not the valves that are causing it. Also check the spec on your valves for your bike. .007 for the intake doesn't sound right. Should be .006in and .008ex. You should really invest in a manual. Guess work doesn't slide with engines. Especially 4 stroke dirt bikes, and more so 04-06 rmz250s.

Edited by Mxerdude179

What exactly do u mean by count the even number of teeth between the trimming marks.?How would it help check timing? The exhaust valve can be between .007 and .011 I wanna say and intake is between .005 and .009 I know for a fact I'll check the manual when I get home. Once again thanks for the info and help!!! :)

You should see two dots embossed on the side of each cam sprocket. One dot should face upward at exactly 90 deg and the other dot should be at 360 deg on the intake cam and 180 deg on the exhaust cam. Make sure those are lined up with the top edge of the head. You should count 13 teeth between each on each sprocket or something. Check your manual for the specifics. Cam lobes should be facing in opposite directions laterally. You should also have a timing mark on the stator. If your timing is correct and valves are in spec then your rings are shot. Time for a top end. That's my opinion.

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