[Cross849]

I have acquired a 2002 crf450. When i bought it the kick starter was broken. I replaced it and tried to kick and the kick start wouldnt move. I had read all the compression stuff. So i pulled the plug to see if that would help it move but to no avail. I popped the bike into gear and rolled it backwards and could hear piston move. At this point the kick starter would move but only until the bike got on a compresion stroke and then almost as if it is locked. What could the problem be? Any help would be apreciated. Also it seems like it will only make about 3/4 turn when trying to turn by hand.

[Cross849]

Is there any chance it is just out of time?

[JimDirt]

Welcome to the site !!

Yea i would definitely check the timing , make sure the 3 timing marks are aligned , and pull the valve cover and physically look at the chain , the timing marks on the sprocket , and the tension on the chain , if you can lift the chain off the sprocket then what i am thinking is the issue would be the timing chain or tensioner , i would first guess that your timing chain has stretched and has possibly caused the tensioner to un-spring or blow apart , if it did , most likely the timing chain is bound up at the retainer guide down by the crank that keep the chain from falling down , if its wadded up down there , the engine will move slightly and that's it ,(or a valve is broke and hitting the piston ....hopefully its the chain)

Do you have a manual ?? , if not i can post up some images from mine to guide you thru the timing checking process

[Cross849]

I do have a manual will definatly check that timing chain and see what it looks like.

[Cross849]

Looks as if it is a bent valve. If the piston looks ok. Do i only need to replace the valve and spring?

[JimDirt]

Ouch !

Well , i would be worried that if the valve hit the piston enough to bend it , then most likely you will find (even without major visible damage to the piston surface) that is highly likely that it put a major load on the rod/crank bearing , what "can" happen is that you could replace the valve/s , and put everything back together , and go to fire it up , and have a rod knock , i have seen it happen before , and then you will be out all the effort (and some money) , then have to go ahead and tear the engine completely apart , and replace the crank

Its a hit and miss issue , and generally , just replacing the valve , is not going to fix all the damage , and possibly create more damage if it causes something else to let loose , personally , i would not take the chance , since you don't know how this happened , so its a crap shoot at best , you might get lucky , but you might not , again , i would rather be safe than sorry , and i know its a larger expense , but in the long run i think you would be better off

Replacing the crank

Replacing the piston

Replace the Valves

Having the head professionally serviced and repaired (the valve seat WILL be damaged and needs cut or replaced) , OR , Replace the head with a rebuilt one

I truly believe , this is your best option/solution , just do what your budget allows , but do it right as far as the head and crank goes , wish i could say just go ahead and replace the valve and go ride , but , i don't believe that is the way to go , i think it will cost you more in the long run , and most likely (especially if the engine was running when it bent as opposed to someone starting it when it did , which i believe it was running) , and the fact that you have no idea what exactly happened and how much real damage that has not been detected is there


I know its not what you wanted to hear , but unfortunately , there is no telling what caused this to happen , and it would be best to replace all parts involved to be safe , you will end up with a fresh engine that you know will last , and the security of knowing that it was done right

I love my 02 , its almost as fast as any "new" 450 (its AS fast as any 450 up to about 2012)and it will hold its own on the track or the trail , i have a 12.5-1 JE piston in mine , and Stainless Intakes , its otherwise stock engine wise ...

The older ones are still worth the effort to redo

This is mine