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Can some help me understand this upgrade to 325cc?

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well it looks like they are fixing a serious piston scoring problem from a 300 big bore or it could be another bike, I do like that KOSO replacement cluster.

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Going for the 286cc, work should be completed by this weekend. 

 

I wrecked my crankshaft, piston, cylinder head etc anyway (long story) so I think its worth the risk. The guy says he can get the bike up to 27hp with 286cc, 35+ with the 325cc. 

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Going for the 286cc, work should be completed by this weekend. 

 

I wrecked my crankshaft, piston, cylinder head etc anyway (long story) so I think its worth the risk. The guy says he can get the bike up to 27hp with 286cc, 35+ with the 325cc.

Where are you getting this work done? I've got a takegawa 305cc kit to go on in January. I've found dirtshop are willing and able in Bangkok but it's nice to have options...

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Where are you getting this work done? I've got a takegawa 305cc kit to go on in January. I've found dirtshop are willing and able in Bangkok but it's nice to have options...

If you use the Takegawa Kit , let me tell you this Kit don't work together with the 63mm stroke of the CBR300 crank .

 

It has a lubrication hole through the Cylinder wall that end up between first and second Piston Ring at BDC with 63 mm stroke and the engine smoke like hell .

At 55 mm stroke the hole is at BDC below the oil rings . no Problem .

 

second problem is the 13/1 compression Piston . with 63 mm stroke its even higher and to lower it needs a lot of aluminium removed from the Piston and head.

Starter motor make Trouble with the high compression too .

 

I have done it myself , i am shure everything was installed correct .

349 cc with 11,5/1 Piston

Cylinder coating fail after 1500 km , jam Piston Rings.

 

Now with BB Kit 2500 km without any problems.

so with the Takegawa better stay at 305 cc.

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Ok they use an Wiseco 40070M08100 piston. 81mm= 5mm overbore.

Reslevee the cylinder and for the 250 stroke You get 286cc.

And with the longer stroke 300 You get 325cc.

I bouth an piston from Lion parts. They delivered wrong rings,

and refused to answer mail !! At last i find rings on Ebay.  3189XG

And Wiseco says use the standard head gasket ( 76mm ! ) ! !

Find 81mm at Ebay. Cometic gasket C8832-EST

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Just read the OP's first post.

Location Thailand: asking for help on-line to translate Thai into English is bizzare.

 

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 Hello whats wrong with my answer ?

 And latche some 12 gram off the piston to get down 11.7 compression.

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