300ex topend still no start pt 2

[cbrooks118]

Hey guys, just a follow up. I had a friend come over and help me tear it down again. we both checked and rechecked timing again...we put the timing gear on cam shaft, with line on top, two lines aligning with the head, we put first bolt in, turned crankshaft one full rotation to put second bolt in timing gear, the chain turned with the crankshaft, however after reassembling the rest of the bike and tried to start up, nothing.... took off valve covers and hit starter real quick, and imagine our surprise when the camshaft did not turn at all! Why would the gear shaft turn when aligning timing, but not when you crank motor? Also if you try to start it while in gear with clutch in it lurches real bad? Any help would be appreciated.... this is first 4 stroke rebuild so go easy on me

[zeppelin]

is the starter actualy turning the motor over?

[cbrooks118]

yeah, when spark plug is out, i can feel the compression!

[zeppelin]

so what your saying is the starter is turning the crank over, but not the cam. but when you put a socket on the crank and turn it over yourself, the cam does turn? man that is weird i have never heard of that happening before.

[cbrooks118]

could something be binding it down? how free should the cam gear turn when you are turning the flywheel?

[cbrooks118]

could something be binding it down? how free should the cam gear turn when you are turning the flywheel?

[zeppelin]

is the motor stiil apart right now, it would be worth a shot to take off the clamps that hold the cam down to make sure nothing is binding there, but i doubt that is your problem. if that was it the motor wouldnt turn over at all.

[bwamos]

You're cam chain is not on the lower sprocket on the crankshaft.

When you have the head cover off, there's no pressure on the cam so it turns easily when turning the crankshaft.. but installing the headcover adds resistance from the rockers and is causing the chain to slip on the crankshaft because it's not on the lower gear/sprocket.

You either need a long screwdriver to finagle the cam chain back on it, or you'll need to remove the clutch side cover (and probably the clutch). You should be able to get it on there with a long skiny screwdriver and some patients without having to remove the clutch side components..

That's my theory.

[cbrooks118]

just took off valve covers and hit the starter for the fun of it. cam turns easily... however, when i put back on the valve covers the rocker arms seem to be holding the cam from turning..... in my opinion i thought you could really put the cover back on to fit correctly if your rockers aren't on there correctly..... sorry for wasting everyones time with this, i guess i'm just not that bright.

[cbrooks118]

didnt really think about it slipping off the lower gear. I will check on that tommorrow after work.. thanks for the advice

[Cody_300ex]

Originally posted by bwamos
You're cam chain is not on the lower sprocket on the crankshaft.

When you have the head cover off, there's no pressure on the cam so it turns easily when turning the crankshaft.. but installing the headcover adds resistance from the rockers and is causing the chain to slip on the crankshaft because it's not on the lower gear/sprocket.

You either need a long screwdriver to finagle the cam chain back on it, or you'll need to remove the clutch side cover (and probably the clutch). You should be able to get it on there with a long skiny screwdriver and some patients without having to remove the clutch side components..

That's my theory.

Exactly what i was thinking, Almost happend to me recently when I helped rebuild a motor a few weeks ago..

[cbrooks118]

Thanks for your experience and advice from everyone who responded. The chain did indeed come off from the bottom, got it togethor tonight and it runs great. I will break it in in the next couple of weeks! Thanks again everyone....

[bwamos]

No problem, glad we could be of help. :)