How screwed am I? Cam tensioner fail

2009 wr250r 5500miles

Freshly rebuilt top end and new cams. Rode 60 miles on single track and ran great!. Get home roll it off the truck started it up to drive to the garage and it died and would not start. After trying all the regular stuff opened up the cover and boom out of time. Exhaust cam spun about 7 teeth off tdc. Its at the dealership now to find out the total damage. Just trying to get worst case/ best case so I know that they are not jerking me around when they tell me the cost(happened on my last bike and was very nervous to bring it to a dealership again)

Thanks for any help

Some disassembly is in order, I believe.

When the cam jumps timing like that, the worst thing that could happen is that the piston meets the valve at a high rate of speed. That high-speed contact is usually where the carnage happens.

If you're worried about your dealership jerking you around, ask to see the damaged parts they're replacing before you authorize any work from them. Sometimes the damage is a little more obvious; a cracked piston will have a crack in it, a bent valve will be bent, etc.

Have your dealer save all the old parts they remove so you can do some measurements on your own (and, you know, report back to us!). There's a measurement in the service manual for the service limit of a cam chain (x inches per number of links) to see if it's stretched. If they replace the cam chain guides, check the old ones for damage/wear.

My motor is getting a little rattly, and I'm at 10K miles. I've also got a manual tensioner on order, so hopefully that solves that issue. A new OEM cam chain is ~$15-20, so I'm probably going to go in and swap that out as well just to be on the safe side.

Were there any other symptoms that you noticed prior to this happening? Did it just up and jump timing?

mechanic called back today.... all he had to do was re time the engine. He said he had no clue why it got out of time, no bent valves or anything. everything was in spec (chain/ valves) Tensioner was in working order. Im going to take it for an easy 20 mile ride tomorrow. crossing fingers on no phantom issues.

also brokenagain. no there was no symptoms it felt exactly like stalling the bike and that was it

I find that strange. I mean, I'm no mechanic, but at the same time, the chain jumps timing because it's not under enough tension to hold it against the sprockets in place.

I also find that extremely lucky. Count your blessings! Glad nothing expensive happened!

Lucky guy... not too many exhaust cams are going to be out 7 teeth and not crash the piston into a valve.. it must have been a retard timing condition and the open valve followed the piston down after TDC.

The chain must of had some serious slop to ride above all the cam gear teeth. Its always a good practice to turn the engine over a few times by hand with a ratchet /socket.. with the valve cover off to view/ check that the tensioner is properly engauged and tracking against the chain ok.