cr500 in a 250r?

[crablaster]

anyone ever seen it or done it? im not a big 2 stroke fan but i was thinking that would be a nasty bike

[Langbolt]

I've read articles and have seen these done.....The Problem is the CR 500 motor doesn't have a counterbalancer....and is also not meant to rev as high as the 250r. People that do build them have to dampen the motor with rubber mounts and pipe it to keep the revs below the stratosphere. I have a buddy that thought Lets take the 250r bottom end and attach the cr500 cylinder....it's still in the works....tons of welding and machining was required and a custom Crank/Rod were fabricated.Someday he might finish it....

We're still better off with the 330/350 kits.

PSI came out with a 425 but I believe it had heating issues & CP industries came out with a 510 Sabretooth that made 98hp....but never saw it evolve.

I guess BIGGER is just a bit TOO MUCH.

Here's a comparison of Piston sizes......What a difference!

;o)

[GOTFEAR]

i have a 250r laeger frame changed it over to a cr500 motor haven't finished it only need finish up the front motor mounts but will be for sale soon. its not a hack job its don right

[00.400ex#55]

It can be done. It is alot of work though and im realy starting to wish I had just built a banshee instead.

If you are not sure you want to do it read this first. It will tell you everything you need to know.

http://forums.everything2stroke.com/honda-trx-250r/19157-cr500-250r-frame.html


This is mine still with a 250r pipe and poorly jetted. Not running it's best but im still working on it. I stall it at the end becuase it woudn't idle just shut off even with the clutch in. In the video it's making about 45hp and 65ft-lbs running the way it is.

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i203.photobucket.com/player.swf?file=http://vid203.photobucket.com/albums/aa289/quadracer56/MOV00021.flv">

[atvmxr]

the LT 500r motor is counterbalanced... ;)

[rustyATV]

Originally posted by Langbolt
PSI came out with a 425 but I believe it had heating issues

I heard that the few people who got that to run reliably, were running two radiators.


Originally posted by atvmxr
the LT 500r motor is counterbalanced... ;)

I've seen a couple of LT500/250R hybrids on eBay. I understand, though, that you want to be careful of which generation LT motor you use, and then some mods are advisable for reliability. Just what I've read, though, no first hand experience. I had thought of trying it to build a torquey woods bike.

[atvmxr]

Originally posted by rustyATV
I understand, though, that you want to be careful of which generation LT motor you use, and then some mods are advisable for reliability. Just what I've read, though, no first hand experience. I had thought of trying it to build a torquey woods bike.

doesnt really matter what year motor you use.. but yes a few tricks to greatly improve reliability. bore it to .060" over and its ~540cc and still have a 3-5 bores left (I like up to .120").

a PV 540 with a Q pipe = insane low-end that just never stops :muscle:

[00.400ex#55]

Zilla motor is a better choice they make about the same power as cr500 anyways. The only downside is fining one though. There is a few cr's on ebay right now but lt's are hard to come by. And I beileve .060 over is 517cc not 540. A 540 would be .140 over..

[DEVINF450R]

I am not even a huge fan of hybrids, never rode one to be honest. I think they are too much work for me..lol but that 300ex looks pretty sick IMO. looks pretty fast for only 45hp

[rustyATV]

Originally posted by atvmxr
doesnt really matter what year motor you use..

Isn't there an early version with a 7-stud head and a later 8-stud head? I recall the earlier ones being more prone to head gasket failures.

[atvmxr]

Originally posted by rustyATV
Isn't there an early version with a 7-stud head and a later 8-stud head? I recall the earlier ones being more prone to head gasket failures.

yes, the 87 have one less head stud. so you upgrade to larger diameter studs, problem solved. The 87 also has a larger intake opening and makes slightly more peak Hp. And the 87 has slightly lower trans gear ratio for top two gears. (kinda like the 86 TRX versus 88)

88-90 motors are the same.

[deathman53]

did they do some updates to the lower end in 89? I know if you are rebuilding them, you want to use the 90 updated parts, improves the reliability alot. Also the 87 cylinders had a tendency to twist. So yes, you want the 89/90 updates and 8 stud cylinder. Duncan racing used to have a page on how to make lt500's reliable.

[rustyATV]

On the auctions for the LT/TRX hybrids I read about things like reinforcements welded to the cylinders in a few places to prevent cracking, and the main bearing seats being bored and sleeved.

[atvmxr]

oh Id just love to see what Duncan recommends... from my brief glance it seems they dont even offer a fix for the wrist pin washers... :rolleyes:

my 87 cylinder has the preventative mods done to it and still going strong.

if your really interested to know the full scoop on the zilla's and making them way faster and very reliable and the parts to make a hybrid, go to quad racer hq dot com ;)