KDX motor in a ATV frame

Discussion for swapping a KDX motor in a MX frame...
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prityboy69
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KDX motor in a ATV frame

Post by prityboy69 »

OK I recently bought a KDX motor off eBay I was originally looking for a extra engine for my shifter kart but I ended up winning a 01 KX250 motor at the same time so not wanting the kdx motor to go to waist I put it in a extra ATV frame I had laying around. I had planned on giving it to my son but after finishing it I think it might be a bit much for him in fact I think its quicker than my KFX450. Anyhow people are saying that since the bike motor is not counterbalanced then it will shake a quad frame apart so I was wondering if anybody on here has attempted a hybrid like this and if so have they had any issues with vibration or the frame cracking? Eventually I would like to find a better quad frame or a MX bike frame but for now this thing is a pile of fun even if it is a bit dangerous.
MX KFX471R, 87 250R with 421Banshee motor (Drag Bike), RM80 (son's bike), CR80 (son's bike), E-Ton Viper 50 ( little girls MX quad), PW50 ( little girl's trail bike), 03 Tonycart shifter cart with KTM250SX engine (The Beast)
TheRadBaron
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Re: KDX motor in a ATV frame

Post by TheRadBaron »

Sounds excellent. I'm a 3-wheeler enthusiast in addition to a dirt biker and I'd love one with a KDX motor. In fact, I just might have to start planning to build one. An ATC200X with a KDX motor would be awesome. ATC200(KD)X. I'm not an ATV expert by any stretch of the imagination but I know that a lot of guys swap non-counterbalanced motors into various ATVs and I don't think they have too much trouble with the vibration. I'm pretty sure that my 200X isn't counterbalanced.
I'm not sure why vibration would be more of a problem in an ATV than a dirt bike though I guess there's something to it since most ATVs came with a counterbalanced motor. I always thought it was strange that the ATC250R (2-stroke 250 racing 3-wheeler) came with a counterbalanced motor while the CR250 motocross dirt bikes didn't.
I'm inclined to think that it won't be a problem but maybe someone with more insight in the matter will chime in. You might have more luck posing the question in an ATV forum since those guys would be more experienced with the ATV vibration issues. In the meantime, how about some pictures? I'd like to see your creation. :grin:
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Julien D
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Re: KDX motor in a ATV frame

Post by Julien D »

Many of the 2t ATVs did not use counter-balanced motors. I might even say "most". I wouldn't worry about it too much, aside from inspecting regularly. Personally, I think a kdx200 powered ATC sounds like certain death. But then, I came so close to death on our ATC200 growing up that I would never put myself on one again, ever... lol.
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prityboy69
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Re: KDX motor in a ATV frame

Post by prityboy69 »

Once I figure out how to post pictures on here with my phone I'll post some. Its nothing special it was just one of those cheap china motors quads that look like a small 650 raptor but where it had a CVT motor originally the frame had plenty of room for the two stroke pipe and radiators. I originally tried to put it on a old 250X frame but would have to cut it all to hell to make the exhaust fit . I do have a old 85 200X I could try it on. The rings are shot in the old X anyhow so it could use a new motor
MX KFX471R, 87 250R with 421Banshee motor (Drag Bike), RM80 (son's bike), CR80 (son's bike), E-Ton Viper 50 ( little girls MX quad), PW50 ( little girl's trail bike), 03 Tonycart shifter cart with KTM250SX engine (The Beast)
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Re: KDX motor in a ATV frame

Post by Dman93 »

Definitely post some pics! I'm a KDX/ATC/Quad fanatic and would really dig seeing the setup!
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3j3j3j
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Re: KDX motor in a ATV frame

Post by 3j3j3j »

Sorry to be the hater, but not really:) Why would you ruin a poor kdx like that
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fuzzy
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Re: KDX motor in a ATV frame

Post by fuzzy »

What chassis did you put the KDX into? I've always thought that would be a cool idea. Did you have to do anything on the gearing side? I've wondered about the difference between an 18" and an ATV sized tire, and if the difference could be taken up with simple final drive sprockets. I know when putting a bike motor on a kart the gearing becomes very tall, but they make all the axle side stuff so it's not a big deal. I'm sure with the KDX's WR trans, and stock quad sprockets the setup is quite punchy!
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
prityboy69
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Re: KDX motor in a ATV frame

Post by prityboy69 »

To 3j3j3j I didn't have a bike I bought the motor for my shifter cart but ended up wining a faster motor at the same time so not wanting it to go to waste I put it on a quad frame that we bought for my son and he tore the junk transmission out the second day he had it.

Now Fuzzy gearing was no issue at all it has 13/26 gearing which is a little lower than most Japanese quads but it will pull the front in every gear but 5th & 6th has a top speed of 76mph so no I'm not going to change anything on the gearing.

I don't have much experience with the KDX. I have owned a couple KX250 but from what I can tell this is one heck of a motor and makes a nice ATV motor I would love to have this motor on say a 250 Raptor or a 300ex chassis.
MX KFX471R, 87 250R with 421Banshee motor (Drag Bike), RM80 (son's bike), CR80 (son's bike), E-Ton Viper 50 ( little girls MX quad), PW50 ( little girl's trail bike), 03 Tonycart shifter cart with KTM250SX engine (The Beast)
prityboy69
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KDX motor in a ATV frame

Post by prityboy69 »

I think I may have a picture loaded if this works. Image
MX KFX471R, 87 250R with 421Banshee motor (Drag Bike), RM80 (son's bike), CR80 (son's bike), E-Ton Viper 50 ( little girls MX quad), PW50 ( little girl's trail bike), 03 Tonycart shifter cart with KTM250SX engine (The Beast)
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fuzzy
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Re: KDX motor in a ATV frame

Post by fuzzy »

Pic didn't work, but pretty cool!!!
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
prityboy69
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Re: KDX motor in a ATV frame

Post by prityboy69 »

Ok I been riding this thing for a while and thought I would do a update. I wish that there was more people that had done this swap so I could compare notes with but so far I have done some basic things. I widened out the quad and made it more stable in the corners, extended the rear swinger so it wouldn't be se wheelie prone, and played with gearing so I could get the final drive I wanted. Next will definitely be tires. The ones on it look to be some kind of dirt track tread and don't hookup good off road. Plus the staggering is off. I would like to do like a 20-11-8 rear and a 21-7-8 front so the fronts dig in a little bit harder.

Overall I love this quad. I have pretty much parked my 450 and been riding this thing. The handling wasn't the best until I widened it which had me doubting the top speed but widened and some toe adjustments and it handles like a dream. Overall the performance of the motor is outstanding. It pulls hard all through the rpm. The vibration is there but is isn't a major problem. I did a few cosmetic changes to bring out the Kawasaki heartbeat it has and represent on behalf on the old KXF250 Tecate of the 80's so I bought green plastic's for it and a graphic with my sponsors on it and KDF220 on the tank. It is looking good and riding great. So far I am happy as hell with the time and money spent on this project.
MX KFX471R, 87 250R with 421Banshee motor (Drag Bike), RM80 (son's bike), CR80 (son's bike), E-Ton Viper 50 ( little girls MX quad), PW50 ( little girl's trail bike), 03 Tonycart shifter cart with KTM250SX engine (The Beast)
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