xr100 timing... problems!

i just rebuilt the motor and come to realize my motor on my supposivly 2000 xr100r is a junk motor that came from an older model bike but on a newer frame..

so heres the problem..

the timing is right on the cam and everything... but the timing marks are off from what they are supposed to be on the crank.. seems like nothings matching up right..anyone have this problem before and know how to time it right?

blew out a perfectly brand new intake valve trying to set the timing..i dont feel like waiting ANOTHER week for a 3rd valve and another month and a half waiting to ride please help!

The flywheel might have sheared the key or the key may be missing. Is it a CDI ignition? If the engine is older than '92 it had points. If they put the 2000 ignition on they probably left the key out since the slot for the CDI flywheel is wider (or narrower, can't remember). You can get a stepped key from XR's only(I think). Search.

Another possibilty is the crank gear is on wrong. It is pressed on without a key but I don't think it could be off enough to bend a valve.

By the way, some guys run without the key. The taper is enough to hold the flywheel in place if it is assembled clean and the nut is tight. The key is there to assure the proper position of the flywheel not to keep it from turning.

it has the key.. everythings fine nothings broken just cant figure out the timing marks.

When you line the T on the flywheel up with the arrow, the cam bolts should line up with the top of the head.

And yes, the little "O" on the cam gear should be at "12 o"clock".

That what you have?

Get your piston to the top of the cylinder (look down spark plug hole)and then check to make sure your valve tappets have slack in them, if they dont then rotate one more time. This would be your TDC point and now make a mark on your flywheel to line up with the pointer on the inner case, This should work regardless of where your factory T mark on the flywheel is. I had to do this once before.

see when i get my motor TDC the flywheel is showing its off from where it needs to be with the T marks..should i dissregard it and just make sure theres slack in the valves get the piston to the top, get the cam gear 12 o'clock...and not worry about the T?? thanks

If the flywheel is indeed located with the key on the crank, then yes, you can make a reference mark but I would want to know what's going on here.

For valve timing the only issue is the piston at TDC flywheel position control ignition timing.

You didn't say whether it was CDI or points.

Has this engine ever run for you?

yes it has a key (shears). yea the flywheel is the only thins messing me up cause of it not lining up right with everything else.. im not sure if it is cdi or points or what it even means lol.. im still new at the bikes.

Yes the motor ran for me.. i bought it a few months back and the guy told me the timing chain needed replacing soon..well after riding it bout 10 times it broke down on me..now im at the point of trying replacing parts and now getting the timing right on it.. after getting the motor together i got it cranked and started with all the new parts but it snap crackle and popping in higher rpms like it wasnt gettin fuel..thus tearing the carb apart and cleaned the jets..put it back together n still no luck.. it wasnt the carb, i figure do the timing.. The bike frame is a 2000 xr100r model and its showing that the motor itself is a older xr100 motor..

broke a brand new intake valve trying to time it last week so i just got my new valve in today and should be trying to tackle this problem sometime this week if i can get enough info off of here

please help in any way people!

Get a manual. If you don't know what ignition it has, you definitely need one. Trying to do anything without one is just about pointless. You need to post a pic of your flywheel so we can tell whetehr or not it's a CDI or points. Then we can go from there.

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