I am thinking of just keeping my 86 250R I just got and buying a big bore cylinder, who all makes and sales these big bore cylinders? From what I've seen pro X makes a bad cylinder that CT ports and polishes and sales for around $900, would it work with a fmf fatty pipe and rad valve? does anyone make these cylinders in CHROME?

 

click here for a lot of info about your question.
Big Bore Info.

 

besides CT, LRD makes a big bore motor using the Pro-X cylinder and their own porting, they also make a 295 cylinder with the LA Sleeve sleeve in the OEM cylinder. There might be more companies that make these...another option might be to buy the cylinder Un ported, and have your favorite porter port the cylinder for you.

as far as the reeds and pipe, they should work fine for the 310 or 330

 

Besides what's already mentioned, Sparks Racing also does 310 and 330 kits. From what I've heard they are of very good quality. Check em' out at
www.sparksracing.com

 

I've got an '86 250R with the CT 310 kit. Awesome. LRD, Duncan, and Sparks also make big bore kits. The Pro X cylinder was designed by Allan Knowles, owner of CT Racing. It's built by LA Sleeve since Allan doesn't have the facilities in house, and Allan gets a royalty from every one that's sold, which may explain why some of the other kits cost more than CT's.

I would recommend that whoever you go with, you get the whole kit that's been tested to work together rather than just the cylinder and head.