Hp?

[woodsracer144]

ok so according to this site i found they claim that a stock 92 CR250 engine put out 50 HP at the crank, so what kind of HP would that put at the rear tire?

[Atlanta]

enough.

I have this exact motor as a spare for my 250r and it is health to say the least.

The power band hits very hard on that motor on the atv.

Thats my .02

[jcs003]

i would say about 48 hp. there isnt much hp to lose in the drive train.

[jcs003]

i would say about 48 hp. there isnt much hp to lose in the drive train.

[jcs003]

i would say about 48 hp. there isnt much hp to lose in the drive train.

[woodsracer144]

man JCS you posted the same one enough! haha! computer not working right? haha

[monkeydude36020]

How does that compare to a 400ex? Do they put down more torque than the 250r motor?

[woodsracer144]

Originally posted by monkeydude36020
How does that compare to a 400ex? Do they put down more torque than the 250r motor?

i cant tell you that just yet, im building a hybred 250r engine im taking the cr cylinder on the 250r bottom end, i've only heard of 3 different people doing work on them. one was sparks, FTZ and some top triks or something like that.
the CR cyls are suppose to have a better port lay out over the TRX oe cylinders. The cr cyls get the PV's pulled but on the one im gonna be running you can had them and run it off your hand lever like a de comp. lever on a hybred.

the only reason i got this cyl is cause i've had som cyls done by FTZ and i know they make afast quad on the top end.

in the next few days i'll tell you how well it works.

[jcs003]

Originally posted by woodsracer144
man JCS you posted the same one enough! haha! computer not working right? haha

sorry. my computer is on some ****.lol

[250rPRIDE]

you will loose more than 2 hp. for sure. it all depends on rotating mass wheel and tire weight axle, sprokets and even your chain. it wont change your base hp, but you will get more of it to the ground instead of wasting it out getting everything moven, i have seen guys pick up .5-.8 of a sec in 500ft. just from going to a light drag axle with lighter wheels and tires with a ti non O-ring chain, i may be getting off subject, but regaurdless i was always told to expect 10-15% loss.. i know for a fact this is true for street bikes i have seen tons of people almost cry when they see the dyno numbers!!! ha

[jcs003]

i heard 12-15% parasitic loss on an automobile. on a bike it is minimal at best.

[250rPRIDE]

have you ever used a dyno? i have. and i have seen factory bike rated at 98 100 92hp whatever and guys come in with a power commander and pipes k&n filter and after a run they are still a few horse short of oem specs, and they get mad.. most dont understand hp specs at the wheels to crank.. but only a 3-4% loss no way a streetbike has less rotating mass than a 250r and i see them loss 10%+ all the time...
woods not taking anything away from you a 50hp 250r is going to be a beast no matter how you look at it, i think you will be very pleased.. have fun with it..

[jcs003]

i understand what you are saying. but a 2-stroke has less parasitic power loss than a 4-stroke. also he was refering to a cr250r.
trx has a other variables which affect its rear wheel hp.

a 2 wheel 2-stroke isnt losing much.

[woodsracer144]

Originally posted by jcs003
i understand what you are saying. but a 2-stroke has less parasitic power loss than a 4-stroke. also he was refering to a cr250r.
trx has a other variables which affect its rear wheel hp.

a 2 wheel 2-stroke isnt losing much.

im talking about in a 250r, cause the OE 92 CR claimed 40 Hp stock. i think thats a **** load of HP for a stock 250... so i thought with a good port job pipe and carb i should be about 53-60 at most depending on the fuel i would run( gas race gas or alky)

[machwon]

Like 250R pride says, a 10% loss would be pretty low. More likely in the 12-14% range if everything else is good. Knobby tires vs. slicks will make a 5 hp difference alone. Chain/sprocket condition can make a difference too. I've seen losses in automobiles upto 17%.

[woodsracer144]

what chain and sprockets would take away more? x ring o ring, no ring?

[250rPRIDE]

Originally posted by woodsracer144
what chain and sprockets would take away more? x ring o ring, no ring?

alum or ti. sprockets at least in the rear and a non o-ring chain.. any experianced drag racer digging deep for hp's, will tell ya that.. dragers around here call them cheater chains... haa

[stfu]

Dyno-ed my 01 cr250r at the rear wheel 43hp

[machwon]

Even though I own the tripple nitrated... sprockets, I've seen the changes in chain/sprock sets with bent teeth, kinked chains, etc. vs new chain and sprocket sets.

[woodsracer144]

Originally posted by stfu
Dyno-ed my 01 cr250r at the rear wheel 43hp

what was all done to it?

[All250R]

Originally posted by woodsracer144
im talking about in a 250r, cause the OE 92 CR claimed 40 Hp stock. i think thats a **** load of HP for a stock 250... so i thought with a good port job pipe and carb i should be about 53-60 at most depending on the fuel i would run( gas race gas or alky)
I'm going to go on a limb and say you're not going to improve the CR much without losing something somewhere. They're production bikes sure, but Honda set that engine up for MX and the factories do a pretty good job getting them optimum.

I think people are so used to grabbing quick hp from a TRX that they sometimes assume the MX bikes suffer some kind of problem too. The ATV's in those days were relatively experimental machines and the good old american public sued the manufacturer's pants off. You can thank parents not taking making some common sense choices and whining about it for their early demise. Anyway, I digress. MX bikes are made closer to the contemporary cutting edge technology than the ATV's were. I speculate that in 06 Honda finally decided it was safe enough to make that model year closer to what they were doing with the 450 MX bike already.

[All250R]

Originally posted by monkeydude36020
How does that compare to a 400ex? Do they put down more torque than the 250r motor?
I think the 400ex put out a couple less peak than a stock 250R - which isn't saying much for the old 400. The torque curve I imagine is flatter, but it just doesn't have the power potential to unseat a 250 two stroke. It took the 450 to do that.

Low end torque is for tractors anyway in my opinion (or at least pretty tight MX tracks). I like to wind mine up and launch. You just can't get that sensitive rpm feel with valves on a single cyl.

[woodsracer144]

so then if they pull a 50 on the crank i should have about a 35-40 at the wheels?

[machwon]

Originally posted by woodsracer144
so then if they pull a 50 on the crank i should have about a 35-40 at the wheels?

I usually assume a 15% loss for ATV's, so a stock 250R with 39 crank hp would have around 33 rear wheel hp. A 50 crank HP motor would show around 42 at the wheels.

[250rPRIDE]

Originally posted by machwon
I usually assume a 15% loss for ATV's, so a stock 250R with 39 crank hp would have around 33 rear wheel hp. A 50 crank HP motor would show around 42 at the wheels.

this is exactly what i was saying from the get-go.. one thing for sure is that its way more than a 1-2% loss, believe me i wish that all it was.. ha. but i would say your in the lower 40's at the wheels..