300ex problem

[ACracin300ex]

my bros 300ex is having some trouble. IT is all stock except for kn filter. My dad and i adjusted the valves, b.c there was a clicking noise, backfiring, and absolutley no power at all ( blasters were eating it for dinner). We started it up, and 30secs. later it was making the noise again, so we adjusted the valves, and same thing happened. It sounds like the cam chain is slapping on the guide or something? does anyone know what the sound could be, or why the valves keep going out of adjustment??? any help, or info would be more than greatly appreciated.

[Aceman]

That sounds like your topend is starved for oil. What happens is either your oil pump went out or oil line has a restriction running up to the head. So what's happening now is your wearing the lobes off the cam because it's starving for oil which is causing the need for the valves to be adjusted constantly. STOP now before you tear anything else up. My advise, tear the head cover off the top of the motor and look at your cam for any wear. The lobes should be smooth with no roughness at all. Then I would remove the spark plug wire, crank the motor over a few times and visually check to see if oil is pumping up to the rocker arms or not.

[ACracin300ex]

we have already checked for oil, and oil squirts out with the rocker covers removed. The oil appears black and burnt. The rocker arms on the exhaust valves were severly warn on the side towards the cam, and have already been replaced once. We're stumped on whats happening, and anything to help us fix this annoying problem will be great. The exhaust valves were the ones that keep needing adjusting.

[Aceman]

Have you changed the oil and filter? If it's fresh oil I can't see how it would come out black and burnt.

[Aceman]

Also, when you took off the rocker cover did you blow out the oil passages in it with air? Any sealer blocking the oil passage hole between the rocker cover and head? One more thing, is it a hardened cam (web cam, etc.). That will wear down stock rockers prematurely.

[txlxcpe]

Check your tensioner to make sure it is not letting your cam gear jump teeth. Or your cam chain may be stretched out. Had the problem and it drove me crazy... hope this helps

[ACracin300ex]

the oil was changed less than 2 hours ago, and its appearing black and burnt? also the whole top end is stock, the cam included. This is really puzzling, and when we had the top end apart, we noticed that the chain tensioner was abnormally easy to compress, so that might be it? we are lost, so any more info wou ld be appreciated.

[PA440exRider]

First off dont let no peice of **** blaster do that. lOl Blaster suck wang. I dont know really what it could be. ride hard and funk that blaster up.

[dirtmomma]

Originally posted by PA440exRider
First off dont let no peice of **** blaster do that. lOl Blaster suck wang. I dont know really what it could be. ride hard and funk that blaster up.

1st off this is a useless post:rolleyes: 2n doff blasters are POS's they are good little 2 strokes that have LOTS of potential :D Just get tired of people like you posting stupid chit :devil:

[txlxcpe]

the cam tensioner should lock into place once it is racheted out. If you already have the top end apart I would go ahead and replace the chain. Also make sure the cam is phased correctly. Solved my problem....

[Aceman]

Yes, exactly what he said. You shouldn't be able to compress the tensioner at all without sticking a tool through the screwhole on the back and loosening it. Once the cam chain tensioner ratchets itself out, it doesn't go back in. But since your chain is so loose it's affecting your timing which is making it backfire.

[dirtmomma]

Originally posted by Aceman
Yes, exactly what he said. You shouldn't be able to compress the tensioner at all without sticking a tool through the screwhole on the back and loosening it. Once the cam chain tensioner ratchets itself out, it doesn't go back in. But since your chain is so loose it's affecting your timing which is making it backfire. Hey Aceman I see you have an FST oil cooler on your 300 what did that run ya if you don't mind me asking?? Looking into getting one one of these days Thanks, ~DM

[Aceman]

It was around $104 shipped. The kit comes with everything you need.