I recently purchased a 350l 4x4 and a 400l 2x4 for parts. The 400 had siezed bearing on the crank and the guy I bought it from had stripped some parts off of it for his other bike. I thought I saw somewhere on this forum that a 350 could be converted to a 400 just by boring the cylinder out. The 400 has a good cylinder and head...can I just bore/hone the 400 cylinder, install new piston/rings?? The rod is the same part number but the crank, cylinder, head and related gaskets are all different. I would appreciate hearing from someone who has done this conversion. If a friend of yours knew someone who did it-that probably won't help me-I hate to shell out a bunch of $$$$ just to find out it don't work. Anyone with first hand knowledge????? Thanks-Tom

 

OK, apparently no one has first hand knowledge of this swap. Has anyone ever heard of it or was the post a saw just a load of crap. Thanks to anyone who can shed some light on this for me.
Tom

 

OK Tom, this is the scoop on these motors. The crank and all other things below the cylinder are the same. You cant bore the jug to a 400. You can put a 400 jug and piston in the 350 motor, BUT.......... The bottom of the liner has to be machined thinner on the outside to fit down into the crankcase, and the intake side of the piston has to have about 3mm removed off the bottom so it doesnt hit the case too. I ran into this problem last year when doing this swap. Even Darrell at HPD had not come across this problem. He machined the cylinder for us (we bought the jug from him) for no charge, but I had to modify the piston myself. Hope this helps answer your question,Bubba

 

Thanks Bubba-I was hoping to find someone with your knowledge. Usually someone will say "Oh yeah! no problems, just slap it in there". Thanks for the good info-you saved me a bunch of trial and error headaches.
Tom