Expecting my 351 kit to arrive soon. Is the stock head ok to use with the new cylinder diameter? Have been reading the threads and find no mention of head mods, so I must be ok...
Comments?

 

Yes in fact you will be surprised at how much it wakes your bike up without head mods.

you will love this 351 BB kit it is awesome.

 

thanks Ramjet! I was worried I forgot to have something done an wouldnt be able to install the 351 right away.

 

buy some Gasgacinch gasket sealer as recommended by Bill Blue and use it on the base gasket.
I had a hard time finding it in the local Speed shops and had to order it.
you will be very happy!!!

 

Isn't the head on the 250 the same basic head as the 300? I noticed when pulling the 250 top end off that the valve reliefs in the 250's piston went down past the crown. This seems indicative of a valve design and spread that was designed for a bigger bore. The KLX 300 piston that's going in now obviously has the reliefs located in what I'd classify as a more normal location on the piston top. I'm no authority on this whatsoever, but it makes me think the cylinder head was designed for the 300 to begin with and just accomodated the 250 later. On the other hand, it looks like the 250 has been around for some time if the 1993 designation on the back of one of my factory manuals is any indication. I've hardly seen every piston in every motorcycle, but the somewhat extreme valve relief location on the 250 seems different to me. Most of my 4-stroke motorcycle engine dealings have been with various XR's, Z1's, and such, so we're not talking high tech, cutting edge.

 

You may be right but all I know standard head still BIG improvements with this bike; with the BB kit.

Did you get the pumper carb? If not I highly recommend it. "Out of the chute performance will be outstanding."

See how easy it is for me to spend you're money.

 

I think Bill recently switched the type of gasket he sends out, and you no longer need the Gaskacinch.
Check into it before you order.
Dan

 

wow, you guys are all awesome. My 351 kit arrived today, so I started the process. No instructions with the kit, but reading the threads here (thx armycopter) and the manual has me off and running. I am to the point of removing the cam cap, and had to stop as it is now dark. Will continue in the morning.

Attached photo is of the base gasket and the sealer I got. Couldn't find the gaskacinch, so I hope this napa high temp will be ok. The photo doesn't show well the base gasket material, it is some type of soft metal.

No, RJ, I didn't get the pumper carb, I will up my DJ main to the 132 and the pilot to #40 for the 351. I am currently w 2bros slip on and dj kit 128 main middle needle clip. This runs great, except for decel popping (lots of popping).

Have been taking photos as I go so if anyone is interested I am happy to share

 

Nice, you're gunna love it!

Don't use that sealant, it will break down over time from the petrol.. Find the gasgacinch! Check motorcycle store..

 

The Head gasket is different, the BASE gasket is the same and needs to have a sealer on it so it won't leak oil after your hard work. Take the time and use it.