Anybody ever try to put a 350X cylinder on?

[250Renvy]

Just wondering if anybody has ever tried or lined up the cylinders to see if they could adapt to make the 300ex a big bore?

[2muchquad]

Yes the cylinder will physically bolt on but its so much taller than the 300ex cylinder.If your looking for a big big bore,my 300ex uses a 400ex sleeve.I have a 86mm kit from profab.The 350x cylinder is only 81mm.If your really serious,once you go up in bore,a 350 head will work with little mods as well.This isnt stuff i "heard" but stuff i have done personally.

[250Renvy]

I am building the same thing you have only with a Laeger frame that was built for 300exs. I want to go as big as I can without sacrificing reliability. I am thinking of getting the Powroll 350 Kit but your is at 385? How's the power/reliability?

Do you have info on this profab place?

Is there anybody you would suggest for a port/polish or should I just leave it stock and go with the stoked and bored?

Are you using the 250R petcock?

[RichM1983]

Originally posted by 2muchquad
Yes the cylinder will physically bolt on but its so much taller than the 300ex cylinder.If your looking for a big big bore,my 300ex uses a 400ex sleeve.I have a 86mm kit from profab.The 350x cylinder is only 81mm.If your really serious,once you go up in bore,a 350 head will work with little mods as well.This isnt stuff i "heard" but stuff i have done personally.

What kind of piston do you use? I was gonna use the 400ex sleeve but the piston wont work and to get a piston that will work I had to buy 4 custom made ones that was going to cost $700.

[dork]

FST sells 380(86mm) and 390(87mm) kits and sleeves with headgasket. thats with a stock stroke.

[2muchquad]

Mine has been bullet proof...so far.Get an oil cooler because it definately runs a bit hotter.Profab isnt around anymore but the guy (scott Smith) still does a few things out of his house.I emailed him a few weeks back and he had like 2 more kits left.Dork says fst sells them as well,im not sure on the specifics of that kit though,mine uses the same size wrist pin as stock(17mm) while some have a 18mm which will rquire another rod,i think from a 250es"big red" 85 or so.With a cam,a mild port job and a fcr carb and a exhaust system,they run really well,not 4fiddy beaters but as fast as anything else in the woods.I like it

[dork]

you're right, the FST kits are 19mm wrist pin. so that leaves profab for a stock rod.

[SET THE STAGE]

so there's a lot going on in here and i'm a bit lost. i just have one question

what is needed to make the 350x topend bolt onto the 300/250x bottomend?

[2muchquad]

you can use the 350x head but not the cylinder,its too tall.The piston would be about a 1 inch and a half from the deck of the cylinder at TDC..not good.:(