Does anyone have the inside scoop on the 425R package from PSI. I have been thinking about this and I know it is expensive. But, I want to smoke most modded Banshees (400cc and under) in san drags.

 

That big of an engine isn't likely to do well in a drag. That piston is big and heavy and in a drag hard to get to make quick revs. Even when lightened and other components are lightened I would say it will still be a little sluggish.

A Pro-X 310 or 330 Kit when done properly will have a steady diet of twins. Have you thought about running methanol???

To get a Honda to beat 400cc+ Banshee's will take alot of effort and money, it also requires spot-on riding and tuning, but it can be done. Under 400cc's takes some work but not as much, and is rather enjoyable... ;-)

 

There is no replacement for displacement. It's true the bigger piston might (might) rev a little slower but it makes power earlier and peak power at a lower rpm(big block vs small block). It would hit peak power earlier(and more of it) and the torque would be fenominal(and torque is what gets u goin'/pulls).Thats like sayin a cr 500 doesn't pull(or would be no good in a drag)-not.The more power(and torque) u have the faster u will be.

 

If he's racing 300ft timed sand drags, revs are super important. If you're running fast in the mid to low 4's then that's not alot of time. RPM is a function of power, each revolution created will equate to getting down the track faster. Two stroke engines with narrow power spreads will create more peak power all day every day. In a drag only engine you can do this. Much like snowmobiles that have hi-HP numbers from the factory, that's because a sled only has to have ususable power across a 500 or so RPM range, not the 3000 or so RPM that most quads will require, a drag only engine can get away with half that.

Think of it this way, if you can get a 310 kit to turn 9000 RPM and have 65 HP at that RPM.; versus a 425 kit that can only safely pull 8000 RPM's that has near the same HP(per PSI's claims), the 310 is going to win. In four seconds the difference in RPM, the 9000 RPM engine, 150 rev's per second, for 4.5 seconds that's ONLY 675 revolutions(roughly) to get you down the track. Now take the same engine that can only get to 8000 RPM, 133 rev's per second, 4.5 seconds, that's 532 rev's to get you down the track. That's nearly a 20% difference...

It will come down to set-up, and mucho importantly gearing, rider and whole bunch more of other factors. But I'm still going to put my bet on the 310 kit.

Now...if he's hillracing then yes, a wider spread on the power and more torque is going to be beneficial.

There has been alot of discussion at the SnoWest BBS about ALL the problems with PSI, thier quality and customer service has come into question by many people. It just isn't some moron that can't tune an engine, there has been some serious flaws in thier work and the supporting tech and customer service apparantly has been dismal...

 

regarding PSI's quality, I noticed at Red Bud that Spader dumped their engines after grenading a few of them and is now running Sparks. go figure.

 

A good friend of min had a 265 psi kit. Its not as good as it sounds my 400ex with just a pipe and silencer would beat it on a holeshot with me then i got on it (his quad) and he beat me with my 400. Plus there is alot of other bull, like you have to run 2-3 radiators or it'll overheat this is only a 265 kit the powerband never kicks and to top it all off it sounds like a lt 80 with a pipe
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I know two people with PSI 425 engines and they have had overheating problems also with them. They seem to be very unreliable. I know one person who was running one and went back to a pro X 310 cylinder and likes it better.