TRX250R.ORG
General => Lounge => Topic started by: Victork on February 27, 2014, 03:06:02 AM
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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? (http://forums.trx250r.org/vbulletin_imports/79_881_2017-04-18_9828.jpg)
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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.
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Even so, it is pretty to look at
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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.
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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)
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Is that 250rjunky's work bench?
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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
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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
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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.
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Great point wilkin
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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
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You may be correct, Calvin did allot for PSI until Bruce quit paying for the goods. PSI burned allot of people over the years
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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
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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
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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
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Neil I've heard that same story but from a different source. He was fast when it ran, but he also toasted several motors and that was just in one race weekend. I'm not trying to talk bad about these motors as I have no experience with them.
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If I had to guess it would be the design of the head that may of led to detonation issues when the motor was pushed hard and got hot, not sure if you can bolt on a differant style head on this motor or not.
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If I had to guess it would be the design of the head that may of led to detonation issues when the motor was pushed hard and got hot, not sure if you can bolt on a differant style head on this motor or not.
I cant for the life of me, remember the member got that PSI top end to work, but best as I can remember, I believe he had a guy on Mac Dizzy machine him a new head for it. For some reason the name Kelsy, comes to mind who machined the head, that sled guy I think what he deals with.
Neil
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could be Kelsey is RK Tek and he does allot of snowmobile heads, he is a member on the other board also.
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The old man and I have a puma and a psi 425. The psi we found worked the best with the sheara puma inframe pipe. We also use 48 mm lectrons carbs. The dial dome we set it to make and it was 13/1 compression so we got our builder shave and reshape the doom to 14.5/1 for race gas and have not touched it sines. Same guy ported my puma as the old mans psi and they were dynoed on the same dyno. The psi made 68 hp and I can't remember the torque. My puma with the CPI pipe made 75hp and I want to say 46 ft pounds but I am not positive about that. Needles to say the last time me and him were racing in Oregon from a rolling start he would cheat and leave before me. By the top of 4th gear I was always 3-4 bike length in front of him. We found with the psi the biggest thing holding it back was the psi pipe. We went from like 61 or 62 hp to 68 with matts pipe. We also picked up 3or4 hp going from a 39 pwk to the 48. Also this dyno is hard for number. In the sled world stock sleds are reeding 15-20 hp less then you reed on the internet.
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O ps yes the psi always runs 200 to 220 with the afco rad and my ran about 150 with the afco rad dune riding. My puma now is about 170 with just a oversized rad after my afco started leaking. We also never ran psi's card.
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Hey this is a interesting little read. I am in the middle of doing a dune build with one of these engines. The motor I am using has the yz 490 rod with the kx 500 piston. Should put it around the 465cc mark. I will be running race gas. I got the engine running very well before I stripped the bike for the build. I am excited to get it to the dunes to see what it will do. I will keep you guys posted on the build!