Some Cr500 questions.

[Pvt. Maggot]

just a few questions...

would a stock 250r rad keep a cr500 cool enough?

would the headpipe and silencer for a 250r work on the cr500 without robbing power and whatnot?..

thats about it..just let me know..thanks alot. :)

[skysolo16]

The radiator should work but not sure about the pipe.

[ghak99]

I would not try the pipe, I know 2 stroke pipes are designed to make a certain engine perform at its best, and a 250r and cr500 are 2 totally different motors.

[Flynbryan19]

No the 250 pipe will not work for the 500. The expansion chamber is MUCH longer on the 500 than the 250. Check a 250 mx bike pipe, then look at the 500. BIG difference. ;)

[Pvt. Maggot]

thanks guys :)

[Pvt. Maggot]

when i mean 250 i mean from the quad..those big huge ones...i dunno if that would make a difference or not..but i'd rather not have to cut up a 500's :p

[wilkin250r]

The CR500 is a much bigger motor with a much bigger piston. As such, it has much more low-end torque, but can't rev out as far.

Let's forget about pipe diameter and restriction for a minute, and look at the different pipes and motors. The reason 2-stroke pipe helps build power is because you get a resonant sound wave reverberating inside the expansion chamber. That resonant sound wave helps pull exhaust out, and help build compression in a certain RPM range.

Now, if you know anything about sound waves, a lower-frequency sound wave has a longer wavelength. So if you want the expansion chamber to resonate at a low rpm, it is going to be much longer.

Now, take that into consideration when you look at the 250r and cr500 motors. The cr500 doesn't rev as high, so you need the powerband to be a much lower rpm, which calls for a longer pipe. A low-rev pipe on a 250r would be like a high-rev pipe on a cr500.

[Pvt. Maggot]

ah...i somewhat have an idea of what you just said...so...uhh..i'm guessing that its A.) possible but wouldn't have good low revs but high?...or B.) i have no freakin clue and since your obviously way smarter then me..explain if its at all possible..thanks man lol...wilkin do you get payed to explain stuff..cuz you should..lol...:)

[wilkin250r]

Ok, in layman's terms. :D

That big bulb in the middle of a 2-stroke pipe is called the expansion chamber. It is shorter for high-rev pipes, longer for low-rev pipes. The longer the expansion chamber, the lower the revs and powerband.

The 250r revs much higher than the CR500, because the CR500 is much bigger. The CR500 wants to make power at a much lower RPM, so it needs a longer expansion chamber. There are also other factors, but let's keep it simple.

Basically, the 250r pipe is too short for the CR500 for normal operation.

Now, if you DID try it, a low-end 250r pipe is going to be longer than a high-rev pipe. But even a low-end 250r pipe isn't quite long enough for a CR500. Let's say the low-end 250r pipe makes power at about 5000rpm. (high-rev would be about 7500rpm) Well the CR500 rev limit is about 8000, so a 5000rpm powerband is pretty hi rev for the CR500, even though it's low-rev for the 250r.

[Pvt. Maggot]

yeah i know the expansion chamber and all that...alright but if i cut and reweld a cr500 one won't that change it also?..i'm not sure if i'm going to need to cut and weld or not but thats just an if..so yeah..but thanks for all your help :)

[exatak199]

what about a quadzilla expansion chamber?
could be a hard fit :huh

just my $.2

[Pvt. Maggot]

i dunno if it will fit in the frame though...i'm trying to keep this as top secret as possible...but i want it done right..

[roar]

I seen a ad for service honda where they were putting a cr500 motor in a 400ex chassis. You might want to check out what they used.

[Pvt. Maggot]

they are putting the cr250 motors in the 400ex chassie and putting the cr500 in the 250's aluminum frame..:) but yeah i'll get some teaser pics once i buy some stuff ;) :devil: