big bore?

[xNOILABOYx]

i wanna bore my 250x .80 to make it a 330x.....is it possible,and if so what jets would i have to buy?

[oriclez]

.80 will take you to 260 something cc. To lazy to do the math right now, but if you want to get a 330 kit than look at powroll or profabatv.com

[haywire4130]

don't bother, the 250x has a 2 valve head, it will still be slow. go to powroll's website and check out the 350x/250x conversion. i've built 2 of them and to be honest i have a hard time keeping up with them on my 400ex. the swap is very simple and relatively cheap. the atc350x has a 4 valve head (similar to the 400ex) and it is a very powerful package. your big bore 250x would be an unreliable finicky pile. ebay is a good source for 350x motors. good luck

[oriclez]

haywired you are backwards.... the 250x/300ex have a 4 valve head. The 350X has a 2 valve head.

[Cody_300ex]

Originally posted by oriclez
haywired you are backwards.... the 250x/300ex have a 4 valve head. The 350X has a 2 valve head. Also a .080 piston will proabley make it about a 280. because a .040 piston makes my 300ex a 297, so thats about 3.75 more cc's per 10 thousands over.

[haywire4130]

dude, i am a full time quad mechanic. i've built both 350x and 350x/300ex motors. why do you think the 350x and 400ex have 2 pipes coming out of the head. you got it, it has 2 exhaust valves and 2 intake valves. the 300 and 250 only have 1 pipe, for the 1 exhaust valve and port. i couldn't be surer. trust me, the big bore 250x would be anemic, it can't breathe. enjoy

[wilkin250r]

Both the 250X and 350X have four valves. The 250X has two valves into one exhaust, the 350X has separate exhaust outlets for each valve. ;)

[haywire4130]

wow, i stand corrected! i coulda swore they had 2! actually i did swear they had 2! oh well:huh im an idiot

[xNOILABOYx]

so.......i should go w/ a big bore?:confused:

[Dunlap]

250sx is the 2 valve motor, same as the 300 fwd. 80 over is a 260cc. And the 330 kit of mine was made for the 250x to make it a 288cc, alittle bigger than a stock 300ex which is a 282cc stock.