[BWalker508D]

Hey all. I recently purchased a Vertex 290 big bore kit for my '04 250R. I am about to start tearing it down to have the machine work done for the kit and have the valve seats ground for my new kibblewhite valves. My question is; do I need to split the cases and remove the crank to have the cases machined to accept the big bore? I havent read that this is the case, but I havent read that it isnt either. I havent found much information about the procedure yet. I would think so, but I have no idea. Any help is greatly appreciated. Thanks a bunch.

[124]

I would never mill a case without separating. Particle intrusion in the crankcase is what I would be worried about.