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My 86 KDX200 has been resleeved by one of the previous owners. Can "normal" sleeves be overbored to give the engine a 240cc displacement? I should probably just take off the head and measure how thick the sleeve is, but I'm broke at the moment and don't want to buy a headgasket until I do a rebuild.

Has anyone on here ported their own cylinder? If so, let me know what angles/dimensions you changed, and if you altered the port hight and what results you got. Measuring professionally ported cylinders wouldn't be a bad idea either.



Sorry for the multi-question thread, I've been up for 24 hours straight and want to get to bed.

MX500 wrote:My 86 KDX200 has been resleeved by one of the previous owners. Can "normal" sleeves be overbored to give the engine a 240cc displacement? I should probably just take off the head and measure how thick the sleeve is, but I'm broke at the moment and don't want to buy a headgasket until I do a rebuild.

Has anyone on here ported their own cylinder? If so, let me know what angles/dimensions you changed, and if you altered the port hight and what results you got. Measuring professionally ported cylinders wouldn't be a bad idea either.



Sorry for the multi-question thread, I've been up for 24 hours straight and want to get to bed.

A standard sleeve can be bored to 68.00 mm max. The 240 kit uses a different sleeve, and the 240 uses a 72.00 mm piston.

If you are looking to do a clean-up bore the standard sleeve can be bored to; .010" and .020" over size using a pro-x piston. Or you can use a Wiseco piston in the following sizes;

66.50 mm
67.00 mm
67.50 mm
68.00 mm

Ron

Thanks.

Can I have the cylinder re-sleeved again to fit the 240 big bore kit, or do I need a fresh cylinder for that?

Hi MX500,

I think you could have you existing cylinder re-sleeved to the big bore sleeve, as the big bore sleeve is bigger in diameter. It would be like having it sleeved again for a little more cost than the original sleeve job. Do note though; you will have to have the head re-cut and modified for the 72 mm bore, and you more than likely will need to run race gas.

Ron

Thanks Ron, due to your help you'll be the first person I contact about future modifications and engine work.

If you check this thread again, could I get an approximate quote for a 68mm Wiseco piston (with rings,wrist pin, bearing, and maybe a head gasket) and a bore/hone job to get my cylinder to the appropriate ~68MM size with proper clearance for the piston.



Does anyone else on here own an air cooled KDX200?

Hi MX500,

Boring your cylinder would be $30.00 plus return shipping. This price is for boring and honing your cylinder only. I would need you to remove the power valve system.

I am checking on a piston right now and will PM you with my findings.

Ron