I'm thinking of building a PSI 425 ATC based on the 250R. This would be strictly a sand/fun machine that is used for drag racing primarily. Has anyone had any experience with the PSI 425 mod, or anything similar? I'm looking for input on performance and reliability, problems, etc,etc. I post this because I have questions about the 75hp claim. I figure I should get some input before I spend 3K on a top end and crank.

 

FOr 3K why not go full blown with the CR500 cylinder mated to a TRX250R bottom end motor?

 

I agree, the TRX500R looked pretty damn sweet, but the PSI has some features that the CR cylinder doesn't have, one of which is the "dial-a-dome". Anyway check out www.macracinginc.com if you're interested in the 500R.

 

The 75hp claim is legit, but, you will have a radical motor! But, hey, WTF, isn't that what you're looking for?
The only problems I've heard of are overheating and don't know how serious that is.

 

MP Racing also builds a pretty fast 389, and 440cc Polonda motor. Something to think about.......

 

I have the pro-x cylinder on my 250r. It is the 350cc bore. I use it for drag racing only. I run two different pipes, ct-whale in-frame drag pipe and a ftz side mount drag pipe. I race in 100 yard sand drags with this machine. It has the over-ride transmission and runs on alcohol. It runs 4.7 back to back , with a quckest E.T. of 4.67. Generally the mph is 61 - 63. This honda is faster than any banshee you will line up with in a hundred yard race......unless they have an over-ride transmission and alcohol or both and bored and stroked.
imagestation pics


Let me tell you, it is so much fun out running them banshees on a 250r. They can never get enough!!!
I can only imagine what a 425 would run like. It would have to be the fastest!
BTW My 350r only makes 63hp at the tires.

 

The PSI 425 does overheat. I almost bought one, and it needed two radiators! Wish I would have came up with all the money, cause it was sweet. So actually the 425 might be a bad idea, because 2 radiators equals extra weight, plus more fluids, even more weight.

 

You guys had better watch out for Roostking in the Yamaha forum. He says that no stock 250r can beat his banshee with "standard bolt ons" and that he doubts that a ported one can. He's gonna be at Glamis this weekend as the great 250r destroyer. I used to own a 250r until I got lazy and bought a 4 stroke, so I cannot defend their honor any more. Keep the yamaha beating tradition alive.

 

hey mintychip,

Does Roostking have the new ProX banshee bolted up to the case?


PSI makes a pretty good kit (Bruce is a very good engineer/inventor), but i'd worry about the case grenading even with better cooling.


theNUT

 

Hey guys....who was the pro that tried the PSI engine last year in the gncc series? Anyway.....he had to abandon the PSI engine because it would'nt hold up.