400ex jumpin time new cam chain+Tensioner...... Still?????

[airman88]

i have an 03 400ex , 416 bore, hotcam st1, HD Studs and i started having problems with the thing not starting. before i put it away for the summer build up i was riding it and its was making funny sound but would go away. then i would park it for a minute and when i would tryand start it it sounded like it had no spark and would fire once or twice and not fire. i would finally get it running and it would run fine.
well i tore it apart i had scoring on the back side of the piston and the bottom comp. ring was sized on the back side only. top ring was fine oil rings were fine. replaced the piston and found that it just kept jumpinhg time 45 degrees of every time, checked the flywheel key, still good, cam chain and a half ling broke, replaced it and the tensioner, and it still keeps jumpingtime.... my chain sliders were a little bit torn up like theedges were torn off, but other than that, nobody has a clue what could be wrong with it.
possible crank bearings, altho they didn't seem bad, but anyadvise would be majorly apreciated...

[m36indiana]

ck cam gear could be bent, mine was once had same problem

[airman88]

ck cam gear, never heard of it, is it the cam sproket or what?

[400exrider707]

Originally posted by airman88
ck cam gear, never heard of it, is it the cam sproket or what?

Yes.

[airman88]

i dont think that is the problem because there is just alot of slack in the cam chain after the ensioner is installed, and yes i did reload the tensioner, and im just not sure why it cam chain will not get any tighter? any suggestions?

[Glamis400ex]

cam chain tightener may be wore out or chain has stretched to much.

[bwamos]

Make sure the chain did not come off of the lower sprocket at the crankshaft.

Honestly, sounds like what you've got going on.

Either that or they gave you the wrong chain.

[airman88]

no i got the new chain fro a running motor, the tensioner is new, and i just replaced the chain and im pretty sure it is still on the gear b/c the chain is not that loose, like it is loose enought to slip or jump but not enought to fall off. it is about a half link to loose.

[lpmaster]

how did you figure out you were juming time? is it getting timed correctly initially? do you run a base gasket? have your head decked at all?

[400exrider707]

Originally posted by airman88
no i got the new chain fro a running motor,


So you're saying you've got a used cam chain then? Sounds like that may be the problem.

Bwamos - if it came off of the crank, it wouldn't even turn the cam over when he tried starting it, it would just spin on the crankshaft.

[lpmaster]

i haven't been in an ex motor in a while but wouldnt 45 degrees be more than a tooth?

[airman88]

im not sure the 45 degrees was an estimate, the motor was timed correctly, i checked and rechecked it. i would start it up it would fire right up the run for about 2-3 sec and jump time. the head is stock and i am running a base gasket the way i know it was jumpin time was after it would stall and die, i would put the motor at TDC and the lines on the cam sprocket were turned clockwise "about" 45 degrees.

[JOEX]

Originally posted by airman88
im not sure the 45 degrees was an estimate, the motor was timed correctly, i checked and rechecked it. i would start it up it would fire right up the run for about 2-3 sec and jump time. the head is stock and i am running a base gasket the way i know it was jumpin time was after it would stall and die, i would put the motor at TDC and the lines on the cam sprocket were turned clockwise "about" 45 degrees.
If it's really jumping that far i'd think there would be some piston to valve contact:ermm:

[josh31]

your flywheel key isn't sheared off is it? I have had this happen once to me. Make sure piston is on TDC, Cam gear is lined up right and the marks on the flywheel line up with the left side cover. If they are not lined up, there is a good chance this could be the problem.

[airman88]

no the key is still good, i thought that could be the problem but it wasn't, i am positive it is the chain that will not tighten up all the way, i am gonna try a new chain and tensioner and slides to see if that is the problem, if not i have no clue...

[Toadz400]

Just make sure to get a new chain this time. The one you threw in was probably stretched already.

[sandspanker]

:) Hey make sure that the cam gear is not turning on the cam itself. just one more thing to eliminate. I would get a new crf 450 chain to put in it. they are real cheep from service honda. :p