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KDX 200 bored to a 300?


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Do you have any pictures of the bike?

Do you have the piston out and measured it? Or did the PO tell you that was the size of the piston in there?

 

I don't think a ~72mm piston will get you even close to 300cc.  A 200 uses a 66mm and a 220 uses a 69mm.  I don't see 3 more mm getting you 80cc's.

Edited by H-B-R
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If it does actually have a 72(+)mm piston, it's most likely has a Eric Gorr 240 kit on it (but I'm thinking the 240s were based on the 220 motor). They were a sleeved cylinder that still used the power valve on the H models, but from everything I've read, they were an unreliable PITA. Pull it apart and see, if it has a sleeve and a 72 mm or slightly larger piston, this is most likely what it is. EG also did the 225 bore and replate kits too. Those used in the neighborhood of a 70mm piston and plated cylinder. Looking at the Forward Motion site, the 225 kit is all that's offered now, but he probably has some leftover 240 kit pistons around. 

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Do you have any pictures of the bike?

Do you have the piston out and measured it? Or did the PO tell you that was the size of the piston in there?

 

I don't think a ~72mm piston will get you even close to 300cc.  A 200 uses a 66mm and a 220 uses a 69mm.  I don't see 3 more mm getting you 80cc's.

The piston just has 72.25mm on it. I know the guy who had the bike before me. Ran fine for him. Alot more powerful than the kdx 200 I had bored. he stopped riding it cause it wouldnt crank. I bought it and took a look at it. The piston is actually cracked. Its still the 200 cylinder.

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If it does actually have a 72(+)mm piston, it's most likely has a Eric Gorr 240 kit on it (but I'm thinking the 240s were based on the 220 motor). They were a sleeved cylinder that still used the power valve on the H models, but from everything I've read, they were an unreliable PITA. Pull it apart and see, if it has a sleeve and a 72 mm or slightly larger piston, this is most likely what it is. EG also did the 225 bore and replate kits too. Those used in the neighborhood of a 70mm piston and plated cylinder. Looking at the Forward Motion site, the 225 kit is all that's offered now, but he probably has some leftover 240 kit pistons around. 

 

 

With stock stroke, that does put it at 240.  Good answer.

 

From:

 

http://performancetrends.com/Definitions/Cylinder-Volume.htm

 

 

1) First is the swept volume, which is pretty easy to figure out. The formula for the Swept Volume of the cylinder is Pi X radius squared X the height. For engine's, this would be:

     Swept Volume = 3.14159 x (Bore/2) x (Bore/2) x Stroke

 

 

 

EDIT:  and at 72.25, don't forget to add a touch for piston clearance, as 72.25 is not cylinder diameter, though close enough to figure out what he has. 🙂

Edited by KDXGarage
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I have heard of Wossner being the most popular choice for the KDX 240cc over-bore as they offer a 72mm/72.5mm/73mm

 

http://www.wossnerpistons.com/products/mode/filter/search/Kawasaki?fitment-category-id=BBB40D59-0BEE-E011-963B-000C29296656&fitment-category-name=2+Off-road#&&/wEXAQUhY29uVG9wQ2VudGVyX2N0bDAxX2RpdlByb2R1Y3RMaXN0BQE2kb36ha1ve57bAQpLvPOPMHsCVB8=

 

Link may not work properly, you will have to search your year and model

Edited by Gotanubike
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I have heard of Wossner being the most popular choice for the KDX 240cc over-bore as they offer a 72mm/72.5mm/73mm

 

http://www.wossnerpistons.com/products/mode/filter/search/Kawasaki?fitment-category-id=BBB40D59-0BEE-E011-963B-000C29296656&fitment-category-name=2+Off-road#&&/wEXAQUhY29uVG9wQ2VudGVyX2N0bDAxX2RpdlByb2R1Y3RMaXN0BQE2kb36ha1ve57bAQpLvPOPMHsCVB8=

 

Link may not work properly, you will have to search your year and model

That's a great link and should provide the required over-bores.

Edited by kenpowell
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