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Power Mods for a 97 kdx220R

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Ok I've got my bike lookin like I want, and this year I think I'm going to tackle the power band. Kdx has a great powerband, don't get me wrong, I just want to blow my riding buddies away:ride: . Is there anything wrong with that?

I've got an FMF Gnarley woods Pipe, and that is about it for power mods. Its set up really well right now, I haven't fouled a plug in it for 3 years now(knock on wood). What do you guys recommend?

JD Jetting kit

Turbine Core II silencer

Air Filter? Intake Mods? Big Bore? Reeds?

The sky is the limit.:applause:

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If you don't mind me asking, why did you go with the woods pipe over the rev pipe on the 220?

www.rb-designs.com has some carburetor modifications that most everyone seems to love. You might need to swap to a KDX200 carb first, though.

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I went with a gnarley pipe because I need the lugging power with low end torque which is what that pipe offers. I'm not an mx'er. The rev pipe sacrifices that low end torque and just requires high rpms to get into its powerband. My style of riding is offroad hill climbing. The KDX was ment to have that low end torque thats what it was designed for. Also, the bike came with that pipe. It makes it have a 4 stroke lugging but that 2 stroke snap!

What pipe do you have on your KDX, and what do you think about it?

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I don't have a KDX220. I have 1987 and 1994 KDX200's with FMF pipes, but that wouldn't aplyy to your situation. I have a friend that has a 1997 KDX220. He has the desert (rev) pipe. It seems to work well. From what I have read, most seem to go with that version, so that made me wonder why you had that version.

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There's a ton you can do to get more power from the KDX engine. How far are you willing to go?

If you are looking for simple bolt on stuff, I'd do reeds, toss or modify the air box lid, and jet it. Changing the silencer doesn't gain much in terms of power, but does save a lot of weight.

If you are willing to get into things a little more the RB carb mod is very highly recommended by many KDXers. Having the head modified for a bit more compression and an improved squish band. Higher squeeze actually helps low end more than top end.

Going beyond that you can get into porting, overbore (Eric Gorr will get you to 225cc if you wish), V-force reed setup (differing opinions on the effectiveness of that), and case matching.

Now, you say you want to blow your riding buddies away. What do they ride, and in what way to you want to blow them away? If they are 250 mounted and you want to win drags, get a new bike. If you are wanting to beat them through some nasty trails, you may be better off spending money on suspension work than the engine. I think most people could get down a trail or around a track faster on a well suspended 30 hp bike than a crappy suspended 50 hp bike.

Your opinion on the rev pipe is a bit off. It does not sacrifice low end to make more power up top. It basically leaves the low end power as is, and adds more mid, top, and over rev. A KDX with a rev pipe is still a tractor, falling on it's face around 8000-8500 rpm, the spot where most MX bikes are just starting to make good juice.

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Making 2 posts to keep from getting too long/cluttered in one single post.

My bike mods

Fredette racing porting, head mod, bored carb (approx 36mm)

FMF rev pipe, FMF Turbinecore II silencer, FMF torque reeds (have also ran Boyseen reeds)

Chopped up airbox lid, jetted

Fredette racing revalved shock

0.40 kg/mm fork springs

On the 220 the pipe, bored carb, airbox lid mod, and jetting are key. Reeds and silencer didn't make much difference at all, I've swapped around a bit with those going back and forth to stock and aftermarket.

My biggest disapointment with the bike is the suspension, mainly the forks. I held of revalving them when I did the shock because of plans for a KX fork swap. I tried a number of oil weights, from 2.5W to 10W, and everything in between, even ATF. I ended up sticking with the stock 5W, 95mm level. I run my compression way out (15-16 clicks) for rocky conditions, and they work great there. But for bigger hits the forks suck!

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Adam728 - do the fork conversion. Most cost less than 400 bucks. I use 2003 KX500 forks on my 220, shortened by about 1.5" and revalved. I stuck with the .40 kg springs that are stock with the 500. They work perfectly. The bike is a whole new deal with USD's - I truly believe it is a better bike than the 04 CRF250X I had for 2 years - it is quicker and lighter and definitely handles the slow technical stuff better.

I also reworked the stock forks on my previous 220, gold valves, springs, etc....but the flex and underhang sucked. The steering improves noticeably with the USD's as well as handling. For example, you can hold a line feet up in sweepers with both wheels breaking traction - that was impossible with the old forks.

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I'm done putting money in the KDX. It's a great bike, but there are too many things about it I do not like. The forks, wide center section, huge tank/seat rise, no removable subframe, etc. I bought the 99 KX with intentions of building a hybrid (like ebeck), but I just sold that bike to a buddy.

I always felt 250's were too brutal, but my skills have come a long way in the past few years (heck, in the past 7 months, and I've been riding for 13 years). I made the mistake of riding some other bikes, one of which was a very nicely singletrack-ready YZ250. I'll be putting the KDX for sale soon. First it has to goto Hoonfest tomorrow. Leaving in 6 hours to go ride with a bunch of CR500's for the weekend. I'm thinking of throwing some pink tassels on the handlebars....

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Just a "by the way" . . .

You don't have to get another carb for the RB mods - he bores the carb from the stock 33mm to a 36mm. He does other things that add a lot of WOW to it.

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I always felt 250's were too brutal, but my skills have come a long way in the past few years (heck, in the past 7 months, and I've been riding for 13 years). I made the mistake of riding some other bikes, one of which was a very nicely singletrack-ready YZ250. I'll be putting the KDX for sale soon. First it has to goto Hoonfest tomorrow. Leaving in 6 hours to go ride with a bunch of CR500's for the weekend. I'm thinking of throwing some pink tassels on the handlebars....

I know where you are coming from.... I went through the same thing. Trouble is, for the REALLY technical stuff the KDX is still more fun and more adept than the 250's. I ended up getting both...back in the day I ran a 97 220 and an 89 KX 250 off-road moded (that's what I used to race in hare-scrambles). Now I have an 01 220 and a 2000 kx 250 that I'm in the process of converting (flywheel and suspension mostly). And I'll tell you what... the close-ratio trannys don't cut it for all around use. Y'know you won't get much money for the KDX, so why don't you just stick it up in the attic for a while? You won't regret it! :applause:

PS, I owned a CR500 - ugh, what a brutal dinosaur....you won't have a problem leaving them behind on anything but wide open and hills - pink tassels and all..LOL

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Thanks for all the excellent feedback. Sorry it took until today to reply but I just got back from a ride.:applause: Flipping Sweet!!! Anyways you all have great pointers in which way I want to get it rollin. It tractored up some steep hills with no problem, I was very impressed.

My riding buds ride the following,

07 DRZ400

07 CRF250X

04 CRF250X

06 Honda Forman 600 4X4

06 Yamaha Bruin 400

As you can see they are bigger, and 4-strokers. Right now I think my setup is great, It can keep up with all of them no prob.

I just wanna take it farther, and I'll keep everyone updated on my decisions.

Thanks

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A KDX, modified or not, will have little problem keeping up with those bikes, if *you* can. But the RB mods will wake up that motor for sure.

I have an '03 KDX220R that I bought with RB carb and head squish mods (great bang for the buck) Boyesen reeds and 13/50 sprockets. The former owner also put on a ProCircuit PCII "torque" pipe... more discussion below.

I later added '98 KX forks (with shim-stack reduced).

Even though it had the Boyesen reeds, I decided to buy some VF3s to see what would happen. The VF3s give me an okay improvement in throttle response over the Boyz, but the sneaky thing was that my top speed went from 70mph to 75mph, and it seemed a bit smoother along the powerband doing it as well.

I wouldn't recommend the VF3 mod if you already have Boyz, but if you were going from stock to after-market, folks seem to like the VF3s somewhat better. $$$ is your choice.

With the PC PlatII, the power signs off quickly at upper RPMs, but since I am a single & 2Track guy, it's not an issue, and 75MPH is plenty fast.

The former owner thought he might have made a mistake going with the "woods" pipe over a rev pipe, but I wasn't so sure. Being a new rider, I tend to depend on my low-end torque and wasn't willing to part with an ounce-pound to gain anything on the top end.

I wanted to quantify it, but the best I could do was make a call to Pro-Circuit to ask for their opinion. The tech there said that when compairing their woods pipe to a rev pipe on the KDX220, I would lose "some" low-end torque if I swapped my pipe for a revvy one.

So, I'm stickin' with it for another year even though I slowly find myself needing the low end less and wishing for a bit more revs as my skills improve. If I find my riding style, or my abilities significantly improved in 2008, I *might* swap pipes.

The best thing I did was to have a pro go over the suspenders. My shock was blown and was making my life miserable with it dancing all over the place. It hurt my sand riding and hill climbing and whooping. I was ready to buy a new bike. Then I got it fixed and found that it performs about as well as most of the new stuff out there. Maybe not as consistant throughout the stroke as some, but not worth me spending any more dough on it. I'll be taking in my shocks and forks for maintenance at least once a year. Maybe more often.

Rick

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Well I've got a new Turbine Core 2 silencer installed ready to see some action, and I have new front RACE TECH springs begging to be put on. March in Missouri is a rainy BE0TCH. If you don't like the weather now, wait 15 minutes it WILL change. I know in the straight aways I can't keep up, but I did suprise the 400 DRZ owner when he took off and hit eighty and looked back to see me on his tail still. Right now it runs great. We go through some serious hairy Missouri back woods, and this bike is perfect for me and the conditions I have thrown at it.

I'm ordering a JD jetting kit, and possibly a new intake system and clutch kit.

Any suggestions would be great for what air filter or clutch kit has worked for you guys. I'm looking at the EBC Clutch kit with DRC plates.

GOOD? BAD? WHAT?:bonk:

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Air filter won't really give you any power gain, although I like Twin Air filters because they are slightly smaller than stock, so you don't scrape dirt off when trying to pull it out.

The stock clutch is fine, just add some stiffer springs. My bike has the original clutch in it with EBC springs, there are hundreds of hours on my bike.

If you are looking for performance, I'd go for the RB carb mod. The stock 33 mm chokes off the engine at higher rpm. The divider in the RB lets it behave like a smaller carb at mid and lower throttle openings, but gives you more hp up top. It will make a bigger difference than an air filter ever will.

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Well with the clutch I have now, it won't fully disingage. I think the plates are warped. I don't know if they are stock or aftermarket, but I'm pretty sure they are ready to be replaced.

I can't adjust the lever or cable far enough to get it to disengage completely. It just has a drag to it when the clutch is pulled.

Sorry if this makes no sense. I had a rough night lastnight. I was attacked by Bud Light and a Mexican girl with tequila shots:cheers:. Neadless to say I'm a little loopy right now at work @ 7am.:bonk:

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Pull the clutch out and file down the clutch basket fingers. They get grooved and the plates get hung up, a common problem.

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can somebody please explain what new reed valves do, im a bit confused

Depends on what you mean by "new" . . .

if you're replacing worn stock reeds with fresh ones, I'm guessing you would see more crisp throttle response.

But if you're replacing the reeds, might as replace the stockers with some Boyesen dual-stage reeds - otherwise known as "power reeds" (or "607s" which is the part number for the KDX). These reeds open in "stages": first stage opens with less throttle than stock reeds, 2nd stage opens with more throttle than stock reeds. The advantage is more air flow at smaller throttle openings. If you're jetted correctly you'll have snappier throttle response because there's more power earlier. More details in the following link (scroll down for the different reed products):

http://www.boyesen.com/cwo/OFFROAD#preeds

There ARE other companies that make dual-stage reeds, and there are other types of reeds. Some argue for or against the "others", but the 607s are well-accepted as being an improvement, ESPECIALLY when combined with other mods (an aftermarket pipe and a less-restricted airbox).

Others may chime in on other reeds, I can only rave about the power reeds - they've worked quite well in both my KDX as well as my son's RM65.

One more link about reeds (note the comments about multi-stage reeds):

http://en.wikipedia.org/wiki/Reed_valve

'Hope this helps.

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