how good are these psi motors?

[Victork]

425cc psi engine, guy has a dyno sheet saying it makes 65hp? I would of thought this much motor could do better. How good are these motors?

[rsss396]

well it really depends on how it was setup, believe it or not a stock cr500 is between 50-55hp at the rear wheel, anybody that tells you differently they do not have a clue.

The PSI cylinders were casted by CP Industries who makes the spynx,puma and saber so the casting should be good. The adjustable dial dome heads are a little strange but they did work ok on a snowmobile motor I once had them on, but never dyno'd the motor with them to compare them to a typical non adjustable head.

IMO if its a gas motor and setup as a duner, then those are good numbers if it a drag port on alky then those are low.

Everybody thinks they can go buy a 90hp Puma on gas, but the reality is unless its on alcohol and drag ported you are not going to make that number or higher. I dont believe Nate McCoy has made over 95hp with a puma on the dyno he uses and dynos numbers are different everywhere you go.

[chadlwa]

Even so, it is pretty to look at

[fast350r]

that is one bad looking motor ,,,, I too would like to know how these motors run and compare to lets say a Pro-x ? I know a guy here location that is selling a 425 just like that one.

[Victork]

well it really depends on how it was setup, believe it or not a stock cr500 is between 50-55hp at the rear wheel, anybody that tells you differently they do not have a clue.

The PSI cylinders were casted by CP Industries who makes the spynx,puma and saber so the casting should be good. The adjustable dial dome heads are a little strange but they did work ok on a snowmobile motor I once had them on, but never dyno'd the motor with them to compare them to a typical non adjustable head.

IMO if its a gas motor and setup as a duner, then those are good numbers if it a drag port on alky then those are low.

Everybody thinks they can go buy a 90hp Puma on gas, but the reality is unless its on alcohol and drag ported you are not going to make that number or higher. I dont believe Nate McCoy has made over 95hp with a puma on the dyno he uses and dynos numbers are different everywhere you go.

Good input! I agree with what you say here. I automatically assumed it ran on race fuel and maybe it doesnt. Hes asking 3500 with cr ignition, pipe, and carb. He says it has a hinson basket and 600 dollar gears but cant remember the name(i believe yukons went for 600)

[Rupp250]

Is that 250rjunky's work bench?

[Kevhes11]

Is that 250rjunky's work bench?

That's what I thought, but I just emailed him about big bores and be told me didn't have one... So either it isn't him or he's a liar lol

[Higgy87trx425]

I owned this same exact motor, complete with the pipe carb and intake. It ran hard!! Great bottomend torque and pulled hard into the topend!! Loved the power!. However it came with a few drawbacks. Pain in the ass to start, and had a habit of overheating. Which eventually let to failure. I popped the freeze plus right outta the side of the cylinder. Might try using and electric fan and and a Dualpass radiator if you buy it! Good luck!!
 Thanks Higgy

[wilkin250r]

I'd like to see the dyno sheet, because the purpose and build of the motor is very important, and how that power is delivered.

If the power comes on strong at 4000rpm and peaks around 6k, then 65HP is a very respectable number. If the power doesn't peak until 8k, then 65hp is weak.

[Victork]

Great point wilkin

[C-Leigh Racing]

There was a member some time back, had one of the PSIs & when he got rid of the big air carb & the adjustable PSI head, he could keep it running & ran good best as I can remember.

Back when the PSI cylinders/engines were coming onto the scene, they sponsored Daryl Rath with their products. When he ran the national TT events, it was sure as the sun was going to come up, if you watched him on the track & seen him go to adjusting on that big air carb, about a half a lap you would see him pulling off the track, done seized that bad boy up.

One thing I will say about the PSI stuff, every piece of anything they did, was as nice of a machining quality that I have ever seen. Each & every piece was like eye candy, atv or sled engines either one.

Dave,
Was looking at a pic of Calvin the other day, seeing what he looked like & remembering, back when the PSI stuff first came out, they were set up at the national TT events displaying their products & the pic of Calvin sure looked like the guy at the events showing their stuff. Could it have been Calvin doing that for PSI.
Neil

[rsss396]

You may be correct, Calvin did allot for PSI until Bruce quit paying for the goods. PSI burned allot of people over the years

[JoePA]

What if you ran like a 40 pwk with these instead of the big air carb. Would that have helped at all? my friend has one but no carb. probably make one mean MX motor if ported properly

[Dirt man]

I have the same setup that I use as a spare motor. I never ran the big air billet carb, I would just run my 39 pwk. I have a big Radiator (pro series per4mance)  or something like that and have had no heat issues and I do have a temp gauge that I keep my eye on.  I probably have 35 hrs on it with absolutely no complaints. I bought  it used and have no idea what it's ported for but I can say it pulls like a freight train with 15/36
gearing and 20“ haulers in the sand. It is a little slower in a
drag race than my led 350 or 370 which have dune ports. It
starts the same as the big pro x. I think if I had someone give it
a higher port it would definitely beat my pro-x's

[udontknowme]

i wouldnt worry about what the power is. we have no idea if it was measured at the tires or at the tranny shaft or the crank. or what altitude or what type of fuel or if the dyno operator was a monkey or if the tuner was a 12yo kid. too many variables. what matters is if you make it to the finish line first. but 65hp with gas at the tires sounds pretty respectable. im sure it wouldnt have a problem beating the majority of cr500 out there