KX500 on a T4 bottom end

**Magoo** · 06-02-2005, 05:34 PM

You could always gear down your final drive I would probably just make the kx500 bolt on the new cases without changing the crank. You said yours ran pretty good. I could probably do it for alot less I was just guessing $2500. With all the crap I am putting my cnc guys through they may kick me out of the building if I ask them to cnc some case castings......hehe.

FTGRACING · 06-02-2005, 07:41 PM

Okay guys, this is but isn't off topic. The latest ATV Action mag has the CR250 powered 400EX through www.servicehonda.com. They said the vibration issues were corrected with proper mounts and a 400EX chassies that flexes well. Now do you think an newer KX250 motor with correct mounts would have less vibration. Then after that what would we have to do to get a good smooth KX500 motor in a T4 (rubber mount it???) . Has anyone on this forum ever rode the new Honda TRX250R, I'm just currios. Now for me, I would deal with vibration for my dunner T4 but I don't want it cracking the frame all the time. The welding is free for me but the re-powder coating the frame will add up if I have to do it alot. Not to mention the tear down and assembly time of the quad.

**Magoo** · 06-02-2005, 09:04 PM

I dont think rubber mounting will work at all, you still have that huge piston traveling up and down creating vibration. If the engine has some give in it, the engine can actually jump up in down in the frame. If you are sitting on the seat of a kx500 tecate and rev it up all the way your eyes will vibrate in there sockets and you will not be about to see. After I drag raced this 610 one night, the next day I couldnt turn my eyes without them hurting from being soo sore. Every part of my body ached. I cant understand why anyone would want to go though with this. Did you guys notice the frame on the kx500 bike that good ol john boshma built? it was primered grey where they had to reweld the frame and grind off the powdercoating. This engine of Johns was balanced, crank, clutch, flywheel. John told me as soon as he got it done that his balls vibrated so bad he might not be able to have kids. Then he suposingly built new poly mounts etc....well everyone who has owned this bike sells it on ebay. I have seen it sell at least 3 times. They all say the vibration isnt too bad, but they are trying to sell it.

**Magoo** · 06-02-2005, 09:18 PM

hey dave how much would it cost to have you machine my tecate cases to preform the kx topend?

diesel-mech · 06-02-2005, 10:42 PM

It seems to me that it would be almost possible to rubber mount the kx engine in a T-4 chassis. The front and bottom mount could be fabbed easy enough but the rear of the engine cannot stay a solid mount do to the swingarm. The only way I see is to roll the engine forward and fab mount so the engine mounts to the frame separate from the swingarm. assuming this can be done without the chain hitting the bottom of the swingarm the next problem would be not throwing the chain. Knowing the drive sprocket it on the rear left side of the engine if its rubber mounted it will try to pull to the engine to the left. miss aligning the chain. You would have to correct this with guilds for the mounts that will only allow them to move up and down and not side ways or a twisting movement, or adding a top engine rubber mount in conjunction with all the other mounts.

Maybe you could move the engine forward in the chassis enough for it to clear the swingarm bolt, You would have to mill the cases at the rear mount to have enough space for the fabbed rear rubber mount. Then fab an adapter that bolts in place of where the enigne would normally bolt at the swingarm to the enigne in its new location. You would have some heavy mods to the frame like possibly moving the front down tubes forward or maybe revamping them to have an outward curve to make room for the engine being moved forward.

By Golly it might just work. I can picture it in my head and if I can picture it I can built it! The good news for the drag racers is it puts the engine up front to help offset the wheelie effect of the 500cc engine. You will need to use a really tough neopreme(sp?) type rubber mount because you don't want much flex at all. If the forks on a KX500 takes up the vibes from the 500cc engine than rubber mount should make it bareable on a quad.

KingOfKawies · 06-03-2005, 11:53 AM

What i have noticed on the 1993 and up Kx250s was that the rear bolt for the swingarms are larger. So installing rubber mounts in the holes on the cases my work. I have a set of mounts for the rear i was going to use. The 93 engine bottom mount was farther up in the frame. I was going to use banshee front mounts for that. The front mounts I was going to use some type of rubber bushings. But have decided just to go the cheap way and put a 93 and up cylinder on the T4 bottom end. The KX500 engine would most likely shake the daylights out of you even if it was rubber mounted and balanced. The wife would like it though.

diesel-mech · 06-03-2005, 12:24 PM

My dad has a 1992 haritage softtail with a solid mounted engine, My mom rides a 94 dyna wide glide with a rubber mounted engine. Its night and day between the two. It seems to me that rubber mounting a kx500 engine may not be the perfect deal but it has to make loads of difference as opposed to a solid mounted kx500

FTGRACING · 06-03-2005, 09:08 PM

Only question I have then is how is Service Honda selling these CR250 motored 400EX's. I know ther not Kawie but it is the same thing as puting a newer KX250 in a T4 frame. Get the ATVAction mag and check out the acticle.

tecatetayson · 06-04-2005, 03:29 AM

the service honda 250r is cool but expensive,i think its about $ 3000 for the modds and you need a new 400 ex to do it to.

David Roberts · 06-04-2005, 08:01 PM

Corey,
If you just sent me cases it's 125.00 for the welding, relocating the studs and remachining the cases to accept the KX500 cylinder. That doesn't include machining the cylinder for the stroke and piston height though.