Tested! Raptor with YZ85 engine== GREAT SET UP!! It works!

[jlhughes750]

We just wrapped up a local season here in Tx. using the Raptor 250 chassis with a 90 mod engine!!
There have been a few post on here with questions about doing this setup. We tried it and had great success!!!
My son won the Supermini class in the Lone Star Quad series and raced it in a few nationals.
If anyones thinking of tring this setup go for it, its a great alternative!!

Ours is currently For Sale in the mini quads section!! My son is moving to 250's

$4000 OBO

[exhausted]

I think we saw this quad at LL this year. It looked really good.
We run an RM 85 in one of ours. I wanted to mount the motor through the swingarm, but it looked like we would have to notch out almost the whole left side of the swingarm. How did you do it without weakening the swingarm?

[oscarmayer]

i have similar issues with KX engine. and what I am going to do is make a new adapter to mount the engine just slightly forward of the stock swinger mount so it stays aligned. I will probably have to fab a new rear mount for this and an adapter on the front mounts. but it should work fine.

OP,
Why are you changed out of the 125 frame? it is the same as the 250 with a few slight mods. you could run one of the 250R engines from Honda and it would run like a scalded cat. When we do finally make that leap, I'm going to keep the frame as long as he has not out grown it physically and run the 250R engine.
(crf250R water cooled 4-stroke from Honda)

[exhausted]

i have similar issues with KX engine. and what I am going to do is make a new adapter to mount the engine just slightly forward of the stock swinger mount so it stays aligned. I will probably have to fab a new rear mount for this and an adapter on the front mounts. but it should work fine.


Thats basically what I did.
http://i167.photobucket.com/albums/u126/perpetuallyscrewed/Mobile%20Uploads/20141024_215638_zps2wbprbhq.jpg (http://s167.photobucket.com/user/perpetuallyscrewed/media/Mobile%20Uploads/20141024_215638_zps2wbprbhq.jpg.html)

[oscarmayer]

dude! amazing idea!!! I was thinking I was going to have to do some cutting grinding and welding to fab in a perm mount, but yours is just some flat pieces cut to shape with holes drilled and spacers. that is a much better idea!!!! thanks for the photo!!!! do you mind me stealing that idea? it is there a place that makes kits to bolt these engines in already?

[exhausted]

Lol, thanks. I only did it this way cause I couldnt afford a shop to do it.
Nobody makes a kit that I know of. We just added the cross bar on the bottom of the frame and trackside makes the horseshoe shaped motor mounts for the rm to go in a cobra chassis. In our first attempt I actually just used the factory front motor mounts for the front, but pr2 didnt want us to modify the fatty pipe, so this way we modified the frame a bit to make the pipe fit.

[jlhughes750]

I cut the swingarm out to fit the back of the engine. Then welded a new 1 inch round tube brace a few inches behind where its cut out. the 85's have a smaller diameter pivot bolt. the yz has a lot of meat in the case, so I drilled out a bit to accept the raptor larger pivot tube. We never cracked the stock swingarm, and my son rode it pretty hard.!!
If u mount in frt. of the swingarm then there are pipe fit issues in the frt. and chain tension issues possibly?

[oscarmayer]

ok last dumb question, what motor do you guys prefer and why?
ktm, kx, or yz?
What I was planning on running was a kx65 with a 85cc BB setup. my son needs more corner and torque for jumps than the straights, so with the shorter stroke and ported, this thing really accelerates like crazy. we ran it in the typhoon frame before we moved to the raptor, now i am thinking of moving it into the raptor since we know it works well and we have everything we need for it. i heard ktm makes the most power, but to me parts are also more costly and nothign is easy on the ktm vs. the kx or yz stuff.

[exhausted]

We like the RM/KX due to the power valve giving a little better power curve. PR2 has a pretty bad *** package for them as well.

[ontargetracing]

I have a 2015 kx85 motor I will sell you.. the rest of the bike comes with it also.

[exhausted]

Lol. The new kx is def king of the hill right now.

[oscarmayer]

LOL ontarget. yea so does the dealer! ;)

well i am going YZ. got some amazing deals on a yz85 complete bike with BB setup already and a complete engine as well. so looks liek i will remain all yami this yr.

[mr.miller]

that's how it should be , Yamaha in a Yamaha ( nothing worse than seeing a drop dead 32 Ford with a SB 350 in it) lol

[oscarmayer]

Well, we have dissembled part of the motor. It looks like it turned out to be a true 107cc setup. It has the +2mm stroker crank and 52.5mm piston. Luke's racing is working with us and will get us down to a 96cc limit with a cylinder change. We are discussing either going back to stock stroke with big piston (92cc when done) or even possible staying close to stock bore and using the stroker crank that would put us at 96cc dead on. We will have to wait and see what he finds when he looks at the motor. It is easier for him to have the whole motor for the porting work and new cylinder. If we do end up going back to stock crank, I will probably save 2mm one for a super mini motor build. ;)

lots of options right now. We will see when we complete the build we are goign to set it up for mid range as that is where Austin likes to ride it most in the mid range area so that will give him best power. I'm even going to expirment with 2 pipes I got. I have a stock (2011) pipe and a pro circuit pipe. We will test each with his riding style and find the best one for him.