KDXRIDER.NET

My buddy got a wild hair and has decided to build a KX/KDX hybrid and use his 89 KDX (bored to a 240) motor. I rode this bike all last year and was going to buy it from him for this next season. Well....now that's off the market BUT we have found many, many more parts/frames/motors/etc...in boxes around the area. So here lies my dilemma, and questions for the KDX gods.

I have a couple 95+ frames, and a couple bottom-ends and one good (H) 200 cylinder. I can buy a 220 complete (minus carb) from a guy down the street and use that, or do I send my cylinder away and build a 200, or bore it larger? Anyone use Fredette Racing? What carb option do I go with?

I have lots of options and haven't committed any direction. I'm new to the dirt scene, been riding street for years. I want low-end power, a good dependable woods bike, and a fun ride for a 220# rider at 4000+ feet in elevation out here in Montana. What is the perfect combo?

Thanks, I've enjoyed the site thus far.

-Ben

If the price on the 220 is good, I'd go with it and find a carb. Building a bike piecemeal will nickel and dime you quicker than you realize (note to self: next hybrid start with 2 complete bikes). I am 225# and have taken my 220 from sea level to 7000+ and enjoyed every mile. As for low-end, dependable, fun woods bike...well, you already found this site :-) From a maintenance perspective, the later model As and Hs will have parts available for a while yet. Just my $.02

if the price is right I'd buy the 220 (assuming it's mostly complete) to convert it to a 200, get the head to rbd to do his maigic, get a new carb (ding ding ding: airstriker!) get a top end kit and run it like i stole it.
with all that you'd most likely have more low end than a rbd moded 220.
Flamesuit on

When RB did my carb I asked him about doing the head (200) and he said it probably wouldn't make that much difference. He said it was a better mod for the 220.

I have a 200 and have had thoughts of finding a 220 cylinder to give a try because I tend to use the bottom end much more then the top end so any extra torque would be better then having some extra top end. My .02.

But as said before I would stick with the 95+ bikes for the same reason as said before.

I sent my head to RB, mostly because it needed to be repaired anyway. He did his thing, and I definitely noticed a difference. Yeah, it's not a huge difference. I guess for the price, if you're doing the carb anyway, might as well have the head done. It does help.

never ridden a 220 BUT i do have a 200 and a freshly rebuild 200
the rebuild had been bored over 2 MM which puts it closer to the 220 bore than the 200 bore and i must say IT RIPS

So...what "stock" carb is best to start with, the older 200, new 200, or 220 carb?

Also, I've heard from other circles that Fredette is THE guy to go to for cylinder/head/carb work, yet on here RB is GOD. Any thoughts? Thanks for the good info guys, I'll post build pics of both the hybrid and mine as we get dirty in the shop.

jbg_3d wrote:Also, I've heard from other circles that Fredette is THE guy to go to for cylinder/head/carb work, yet on here RB is GOD. Any thoughts? Thanks for the good info guys, I'll post build pics of both the hybrid and mine as we get dirty in the shop.

Fredette wont do work on alot of bikes. at least from the emails ive sent him he wont even touch my bike

I have had excellent results with the 220 engine: RB head mod is critical, either a stock 200 H-model 35mm Keihin carb or RB modded carb or air striker (I have tried them all), FMF desert pipe. It doesn't have the explosive power hit of the 200, but it has power from bottom to top and does come on when the kips opens. It revs out on top like a 200.

Okay, so the 220 is out of the question ($$$), time to gather up my 200 parts and send'em off to RB it looks like...

The general consensus on here from most people who have all the bells and whistles is:

Leave the cyl alone....If you must port/go big bore there are mixed opinions on here of Fredette, Eric Gorr, etc, do your research. If you are going to do cyl/bore work, let that guy do your head!

Stock cyl, RB is indeed proven to do stellar head and carb mods. If you are working a 220, the 33mm carb should be swapped for a 35, or just send to to RB they all come back bored to 36, slide cut, roughly jetted, etc.

Install pipe of choice.

DFIII Reeds seem to take to the KDX very well, and in conjunction with RB's mods can provide loads of bottom end, even if you chose to build a rev-piped 200 (least bottom).

Does RB bore cylinders and sell new pistons?

Cylinders sent off to Powerseal, heads and carbs sent to RB. 240 big bore motor mounted in KX frame, awaiting splitting the 95 KDX apart for bearings to build that one. An 89 is getting put back together for the lady. Will start a build post with pics soon.

Thanks for all the info guys and gals, this site is one of the best forums I've been a part of.