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dracutrider

New to the YzF's

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Hey. i am in the middle of building a Lonestar 250R geometry No-link framed yzf hybrid. i got a yz400f motor with the frame and had a few questions. my first question is the motor worth using. should i just sell it and buy a 426 or 450? I dont want to go spending alot of money buying a different motor and then spending money on that motor too. so here is my next question. if the 400f motor has alot of potential how can i get that power out of the motor. i was thinking of doing the 417, porting the head, and gettting some new oem ti valves. I am pretty new to the 4-stroke scene. i could tell you how to get the most out of a 250r motor but have no idea when it comes to thumpers. any help would be appreciated.

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You are talking about a quad, right? There is a Yamaha ATV Forum just for you guys.

The 400 had stainless valves, not Ti. It does have potential, but obviously less than either the 426 or 450. It can be taken out to 444cc, as can a 426, but the crank, rod, clutch and transmission are all weaker on the 400 than on the other models.

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