KLX250S jumped time, I hit the starter without knowing and sheared off both exhaust valves. One of the broken valves got sandwiched between the piston head and combustion chamber. The piston head is OK, but I didn't get so lucky with the cylinder head.

You can see in the first photo (with the new exhaust valves installed) that the combustion chamber took a good whack. The second photo shows the nearer exhaust valve in the light. The third photo shows the nearer exhaust valve in the dark with a flashlight in the exhaust port. The last photo shows the nearer intake valve with a flashlight in the intake port. There's only a gap in the nearer valves where the head was damaged.

I'm curious what my best option is here. Trying to salvage the head and lap the valves, replace the head, or something else?

Thanks for your help!

 

You need your valve seats cut. Many times when this happens the seats/guides get damaged. I have even seen this from engines over heated. If you can't find a machine shop in your area LMK. I work at one. I haven't done a Klx yet so not sure if I have a pilot that fits the Kawi guides but I still maybe able to help.
If I don't have the right pilot adapter I can get one. After all I may need it someday.

 

Thank you s10gto. I called the local Kawi service shop and they said they might could do it but would have to take a look at it first and it may just be cheaper to replace the whole part. How much would you charge to cut the seats and which part of the country are you in?

I'm guessing I'll have to reshim the valves after tweaking the head

 

You will need to reshim. If I have a pilot and can just give them a light cut well just cover return shipping. If it is junk I will be able to tell when it's in my hands but even If all the seats need to be replaced I highly doubt if would be more then a new head.

I am in Massachusetts.

 

If you can find an automotive machine shop that has the equipment to do valve jobs, then they should be able to cut the seats and lap everything back. You will need to reshim the valve clearance. How did it jump time?
How the guide clearance feel when the new valve was installed? If the guide was damaged it will allow the valve to wobble and not seat.

 

I dropped a valve and had to put in a new valve guide, that took a lot of cutting on the valve seat on my SR500. I'm thinking you can probably cut your valve seat enough to fix the issue. Again a performance car shop (tuner cars, Hondas and others) can probably do the cutting if the bike shop can't.

I don't see how it would be cheaper to replace an entire head, although it might be. If nothing else I'd see about what the cost would be to install a new valve seat or bigger valves if it took that. Again, done by a high performance automobile machine shop, not something the average dealer can do.

 

We do many import heads. I am thinking the Klx valve stems are 5mm like the 5 valve audi. If so this head is a piece of cake to fix.

If smaller I would need to get a pilot.

 

Valve guide diameter for KLX300 and earlier model KLX250:
Exhaust and Intake 4.500 - 4.512mm

The valve seats are ground to three angles, 32, 45, and 60 degrees.

Ride on
Brewster

 

Thanks Brewster. I will have to check all the pilots but I am pretty sure my smallest is 5mm.