Dropped a valve on the 250 yesterday

For some reason, we dropped the exhaust valve on the right bank yesterday on Bryce's 2004 CRF250R. Looking like perhaps due to some odd wear on the keeper key that it might be the weak link. However, just curious if anybody else has ever experienced anything of this natur. I was riding it a lap in consideration of trading Bryce for my 2005 CRF250R. As I came out of the woods onto the straight of way heading back to the truck I got on it a bit, the bike hesistated for a few seconds and then grabbed, when it did there was plent of power pulling the front wheel off of the ground and then I heard what sounded like the timing chain slapping the case so I immediately hit the kill switch and pulled in on the clutch at the same time coasting to a stop. I got off and pushed it to the truck. Whenever we took the top cover off the timing chain was in tact. However, upon further inspection we discovered that the shim was missing off of the right bank exhaust valve. So, we tore the side case off, still no shim. We continued to remove the rock arm and discovered that the spring, top washer and shims were literally just sitting around the stem of the valve and loose. Upon turning the auto adjusting screw for the timing chain, the shim dropped straight through the engine and onto the ground. The exhaust vavle was bent from slapping the top of the piston 4 times as you can see in the following picture.

Please tell me this is not my old 04 CRF250R! I would guess not since I do not see a rekluse cover on the side or kick stand.

Anyway sorry to hear about the mishap. Did it have any prior head work?

I am curious to know if it came apart cleanly. If you find keepers and valve stem pretty much in tact, then maybe valve float to blame?

In any case don't reuse the valve train components. And the head is not worth rebuilding if it's an 04, unless you put new seats in it. Cheaper to upgrade to 07 or 08 using components from one of those years.

Might get away with a piston kit only but for good measure if it has a lot of hours, consider a crank assembly. I have the tool to press the crank out. And air tools and a flywheel holder.

Nope Curado, it's actally Scott Grizzo's old bike......many on here will find that interesting as we bought it from BikeJunkie.


Ended up being a couple of hairline cracks in the exhaust valve guide that we believe caused the valve to stick and the rest is history.

Got the engine completely back together last night, sub frame is straightened, going to set up the suspension for Bryce's size and weight tonight and hopefully bring her home.

Cool

Suspension is all set up for Bryces size and weight. I never knew how much adjustment could actually be made to a dirt bike until after last night.

Ended up with only $500.00 tied up in the whole bike. That included two exhaust plugs, two extra oil filters and a few other odds and ends.

Picked up a Garmin 800 series with 2012 3D Maps downloaded onto it last night for $40.00 too. Now, I just have to do some research to see if it can be adapted to my 2005 CRF250R.

Damn sounds like you made out

that bike has made its way around the gang huh lol. looks like a big project

Yes Geoff, it definately has done that.

The project went really smooth and didn't have any problems at all.

Going to probably give her a spin or two while we are down at Chadwick to make sure she's good to go before Bryce gets back from Oklahoma.