you'll need a big bore kit like the one jkass posted from ESR. a Pro X 330 or 350 will do for 50hp. it is feesable to get that power on race gas with some pretty high compression. might cost you more than 1500 though.

my 350 cost about 2K is parts alone and then i paid someone close to another 1k to assemble it all and go through the tranny, billet clutch basket, heavy duty springs, new OEM clutch plates, new 5th gear, long rod crank, new main bearings, seals, hardware, rebuilt waterpump, drag/dune porting, hone and complete assembly. i run a 39 PWK keihin carb, ext K&N, 350 big bore LRD pipe and it runs on 111 leaded gas (4.50-6.50 a gallon). not exactly a secondary bike if you catch my drift. [img]i/expressions/face-icon-small-smile.gif[/img]

btw, im not saying my bike makes 50hp to the ground. im sure its close to that. maybe a little more maybe a little less. i dont really care about dyno numbers as much as results on the hill and in the dunes. not too many 450's can dune to the hill and beat my bike and dune back to camp like my bike can. i dont really care about trailers queens. as long as it scares the living crap out of you, who cares. [img]i/expressions/face-icon-small-happy.gif[/img]

 

Thanks HA2.. Im thinkin about scraping the 250 engine now and going with a big bore 4 stroke like the xr650 engine or something of that nature. We'll see what happens. Thanks anyway.