400ex motor in 250x ?

[Corey13]

I picked up a 1990 honda trx250x the other day for 200. It has a renthal swingarm new plastics and a few other things. The motor isnt in the best condition and i want to make this quad rip!! Will a 400ex motor fit in the frame quite easily? I have a welder and know how to use it. What are some motor swaps you guys have done to these? Thanks!

[maddmatt02]

heard of cr500's which is what Im doing after I blow the dirt cheap 300 I just built for mine, also been told 350x motors bolt right in, think you need spacers is all.

[Corey13]

Thanks, has anybody else done or heard of any other motor swaps?

[bwamos]

350X Motor is a fairly simple swap.

400ex motor is doable. I've seen them before, but no clue how it was installed ro how hard it was.

CR500 motor? In a 300ex frame? I don't see this working. Mounts are completely different. Pipe won't fit in frame well, very hard not to get interference. Hard to mount a radiator anywhere. I wouldn't reccomend. Let alone the very short swinger and a CR500 motor would not be a good mix.. lol. Wouldn't the kicker hit the tire on a 250x anyway?.

ATC350X motor swap would be my reccomendation.

[maddmatt02]

I just know Ive seen one on ebay, one on craigslist and one pon a forum somewhere...

when i do it later on Ill let you know... lol

[jay80]

Actually this was up on ebay a little bit ago, guy was local to me but I never got a chance to go see it.
CR500 in a 250x

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=020&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=300121507639&rd=1,1

[Corey13]

Anybody else?

[rooster300ex]

That would be a hell of a ride. My 300ex how it is now raises the front end pretty easy without trying. I would put a +4 or maybe longer swinger on it if I bought that.

[2muchquad]

You could do a cr500 motor if you wanted to,it would jar your filling loose with the vibes though.Amost anything can be put into a 300ex,heres a 300 with a yz426 motor i did a while back.

[2muchquad]

Huh..

[Corey13]

Do you have any more pics of the build?

[maddmatt02]

im debating on that now, except crf450, one cuz I cant put a yamaha in the honda, and figured the unicam head might be a easier fit.

[2muchquad]

No,i didnt keep it for long,one reason was i had to take off the rear fenders to start it every time because the kicker would hit them.Plus i was bored and since i had the yz426 just sitting(still) i figured why not.I just wanted to see if i could do it.Im always up to something:D

[maddmatt02]

you mean when you flipped the kicker out it wouldnt come all the way out cuz of the plastics? could you have grinded away a notch for it to set into while it was out and up?

[2muchquad]

yes it would swing out fine,it would hit the fender if i kicked it over,i didnt feel like butchering the plastic....kabeesh:D

[maddmatt02]

ah. I just started thinking the other day while I was out riding, the 450r's are forward kick but the bikes kick backwards dont they? if I got a crf450, could I get a trx450 side cover/etc.. whatevers needed to make it forward kick, cuz I have a feeling I could end up with a 02/03 crf450r engine wa cheaper than an 04/05 trx450r engine.

[bigblock10]

I am doing a 05 450r swap right now, here are some problems that you find along the way, you will have to


.cut/grinde all motor mounts off

.use a diff swingarm. 400ex or 450r. or anyother that bolt through the motor.

.make new motor mounts

.move/make rad mounts

.make oil cooler mounts

.remove fuel petcock and install smaller one found on dirtbikes "99 cr 125"

.cut the header pipe back by the kick starter

.reweld "tig is the best " the header so it all fits

i am sure there is more but this is how far i am so i will snap some pics some time this weekend and post as i go


DEREK