Timing Chain Tensioner -> 2006 450 EXC

Hello all!

I had a minor fall over the weekend, which resulted in my timing chain tensioner breaking off the cylinder head. I have no clue how this happen other than maybe the heel of my boot hitting it in the fall?!?!?

Anyhow, I cut the motor immediately while still on the ground. My buddy found the broken parts (housing, spring and ratchet adjuster) in the dirt which bummed us out real quick cuz it wasn't going to be a fun walk back to a road. 

I've already ordered a DJH manual adjuster, my question is besides my planning to dump the oil & filters, is there anything else I MUST do before buttoning things back up with the new DJH manual tensioner???

I did make one potential mistake, due to our location and not wanting to push up hill AND not knowing at the time exactly what it was that broke, I did power the motor up and ride the bike up this smallish hill at very low revs and shut her down seconds later coasting down the path. I did not hear any metallic or bad sounds as a result of the crash or briefly starting it up getting it out of the woods so I'm hoping all is well. I've never done this before so I'm unaware whether or not I need to open up the valve cover or not to check for clearances or if that's not necessary (crossing fingers)???

ANY advice would be greatly appreciated!

Sounds like you probably lucked out and didn't have you chain skip a tooth. Don't know for sure, but I imagine the valves would hit the top of the piston if the timing was too far off the correct setting. Guys more knowledgeable would know for sure, and It would be a sure bet that Dave (DJH) would know.

I've just recently bought one of his manual tensioners as well. Im looking forward to getting it installed on my 08 450exc. My chain is fairly noisy with still the stock setup installed.

Back to yours, I believe the plastic chain guide that the chain runs on gives it a slight bit of tension just on its own, and since you took it easy on your ride up the hill with no unusual noises I'd think positive and say you are good to install the tensioner when it comes in and fire it up. But if you want to be safe....because the alternative could be costly, you should check your valve timing per the manual prior to firing it up again.

That was brave to even attempt to start, with it obviously broke. EEEEEEKKKKK!!!!!!

But yeah I think you lucked out.

I agree Spud, I just got back into dirtbikes a few months ago and honestly, I didn't even know what broke, had I known I'd probably still be out there pushing the damn bike. LOL!


Thanks for the advice, I might try to contact Dave (DJH) for his take.

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