cr500/250r motor swap

[TheFontMaster]

How well would this work? My biggest quetion is how would the mounts have to be made up. Would I HAVE to do any cuting or welding on the frame to make the motor mounts? I just painted the frame, and I would like to avoid welding or cutting on it.

[markk]

ARe u putting a cr500 motor in a 250r? That would be one hella quad!, I'v only ridden a cr500 twice, and its got more balls than i even want. Get back to us on how its going!

[TheFontMaster]

Originally posted by markk
ARe u putting a cr500 motor in a 250r? That would be one hella quad!, I'v only ridden a cr500 twice, and its got more balls than i even want. Get back to us on how its going!

Right now I am basing it on 2 things. 1 if I get the junker 250r that I am looking for. Then I will have a 250r motor and another frame. And 2 if I need to do any more welding or cutting on the frame.

I really want to do this.

[deathman53]

a cr500 is NON counter balanced, meaning it will vibrate the filling out of your teeth, and crack your frame is no time. after every ride you will have to tighten all bolts, a cr500 is not what you want to do in a quad. the reason why its not a issue in the dirt bike is because, the dirtbike forks soak up the vibration.

[TheFontMaster]

The motor I am looking at has been ballanced, though I was told it still vibrates a bit. And it is curently in a quadzilla.

[Butters]

you could always go with rubber to help cut down the vibration. i think i have seen that done on here before. i know i have seen the kx500 motor put in a tecate. thats pretty badarse.

[TheFontMaster]

The motor is ruber mounted in the quad it's in now. I would do that if I put it in the 250 frame.

I'm trying to find out if the motor being counterballenced will reduce vibrations enough to not make me frame need any further gussets.

[wilkin250r]

A balanced CR500 motor still isn't nearly as smooth as a motor with a proper counterbalance. Balanced or not, it's still going to vibrate like a mofo.

The CR500 motor is very popular, and is a very common conversion. However, every single person I've ever personally talked to that has done this conversion say the exact same thing. "Damn it's fast." "It vibrates like a mofo" and "I'll never do another one."

[speedfreaksguy]

Originally posted by TheFontMaster
I'm trying to find out if the motor being counterballenced will reduce vibrations enough to not make me frame need any further gussets.

Even with the stock motor, most 250R frames need gusseting. Because of the added weight, horsepower and vibration of that 500, I would gusset the hell out of it.

[TORO1968]

There is a lot more to vibration isolation than just using rubber mounts. Isolator material, construction, size, shape, mounting locations, engine characteristics, etc. all come into play when it comes to this stuff.

Proper vibration damping (yes, I said damping, not dampening or dampning... :) ) will eliminate and/or hide the transfer of much of the vibrations generated by an engine such as the CR500. What's cool about using proper damping is that, besides reducing the amplitude of the vibration as it is transferred to the frame, you can also alter the vibration spectrum in certain situations. This means that a prominent vibration you might feel at one engine speed might not show up until you reach an rpm past the redline of the isolated engine if properly damped. Keep in mind, this would be the ideal solution, but we all know things don't work that way, don't we? :D

Unfortunately, fitting the proper isolators to an atv frame/engine might not be easy to do. Luckily there are all sorts of designs and techniques to work with.

PM me if you'd like to discuss calculations, design, etc... I can help you out. :)

Has anyone ever looked into developing a counterbalancer setup for the CR500 engine? Hmmm...now I'm thinking again!

-Jordan

[Joecool1264]

Why does the CR 500 viberate so much in a quad frame than a motorcycle frame? Or why do you feel it so much more in a quad?

[jiggaman2401]

Originally posted by deathman53
the reason why its not a issue in the dirt bike is because, the dirtbike forks soak up the vibration.

[sickmojave]

If you do a search on this site you will find that the last post is not true. Gabe posted some very good info on this.

[sickmojave]

here I will save you some time.;)

http://www.exriders.com/vbb/showthread.php?s=&threadid=122168&perpage=15&highlight=cr500&pagenumber=1

[wilkin250r]

Geometry still does have a little bit to do with it, mostly how the vibration travels up to the handlebars.

As for strength, Gabe nailed it on the head, the motorcycle frames are much stronger than quad frames, and much better equipped to handle that type of vibration. If you wanted to make your quad frame as strong as a motorcycle frame, you would end up with a 600lb quad.

[TORO1968]

Isolating the handlebars from the steering stem and also altering their natural frequency will also help a lot. Unfortunately, excessive vibration may still be felt through the seat and foot pegs.

I'm still working on figuring out how to reduce foot peg vibrations...If I didn't work so much, I might actually have a chance to do something! :D I suppose you could better isolate the seat/rear fender assembly as well. Hmm...

I agree with Gabe and Wilkin...differences in frame stiffness and handlebar mounting configuration are the main reasons the vibrations from one of these engines are more prominent in a quad chassis than in a dirt bike chassis.


We're getting some good info going here...let's keep this thread rolling! :)

-Jordan

[DamageInc]

Originally posted by Joecool1264
Why does the CR 500 viberate so much in a quad frame than a motorcycle frame? Or why do you feel it so much more in a quad?

Ever ridden a CR500? That engine will vibrate no matter what you put it in. Your hands are still tingling an hour after you get off of it. But damn, are they ever fun...

[LittleD]

I dunno if this has been posted yet, or if its even true, but i heard you can fill your frame and handlebars with expanding foam or silicone to cut down on the vibrations. If you get this project done be sure to post pics because i have been thinking of doing a project like this for a long time.

[86atc250r]

The seat doesn't seem to be that big a problem, you will notice a little, but nothing real substantial (at least what I can tell from the little I've ridden mine). Particular attention paid to frame strengthening and mount strength will pay dividends in helping control/direct the vibration and helping prevent fatigue failures.

I think the bars will be very easy to solve as well. Bars can be attacked by several directions. By isolating them from the stem (anti vibe or similar mounts) and by adding mass to the bar ends (not by filling with silicon, but by the use of bar end weights --- many people confuse the isolating ability of RTV silicon with the addition of mass -- when you fill the bars with something, you are not isolating, you are adding mass, so silicon is not the best choice). The use of a bar without a crossbar support also helps (i.e. ProTapers).

The pegs, however, are a tough one though (beyond strengthening as much as possible).

One thought I've got is isolation via a post mount system, much like a propeg mount with a rubber between. Also by carrying the load and having the isolator as close to the frame as possible - where the amplitude will be the lowest and easiest to control.

[Plante400]

can you say VIIIBRAAAATTIOOOOONNN

gl tho, will rip