Re-sleeved, can I overbore to a 240?

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MX500
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Re-sleeved, can I overbore to a 240?

Post by MX500 »

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.
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RBD
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Re: Re-sleeved, can I overbore to a 240?

Post by RBD »

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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
MX500
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Post by MX500 »

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?
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RBD
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Post by RBD »

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
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Post by MX500 »

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?
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Post by RBD »

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
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