KDX220 Jetting

[jb_dallas]

I just bought a very clean 2002 KDX220 with FMF Gnarly pipe and silencer. The airbox lid has been removed (and aftermarket pipe added), but the previous owner claimed he didnt change the jetting. I am located in Texas at about 600' elevation and running factory suggested 32:1 ratio. What needle position and size main jet should I be running? If that question is too specific, what is the stock main jet size? I havent gotten around to buying a manual yet.

Thanks
JB

 

[reepicheep]

I have a thread here somewhere on the quirks of the 220...

It is one of two things:
1) The torque pipe on a 220 acts like a rev pipe, and the rev pipe on the 220 is just a mess.
2) The rev pipe on the 220 acts like a torque pipe, and the torque pipe on the 220 is just a mess.

Hopefully for your sake, it's 1 and not 2. But I think it is 2.

One of us should dig up that old thread... It has part numbers to check and everything.

 

[jb_dallas]

The pipe discussion reads as follows:
"Installing a torque pipe on a KDX220 will improve performance from idle to about 7500 rpm then fall flat just like the stock pipe with no meaningful increase in over rev or higher rpm performance. If you're looking to improve your 220's power delivery from the bottom to top end then a rev pipe is a must. You'll often see the FMF KG-30 advertised as a rev pipe for the 200 and as a torque pipe for the 220 for this very reason. The torque pipe is still a viable choice for 220 owners who focus the majority of their riding in tight technical conditions or for those who want to maximize bottom to mid performance and are willing to give up some upper mid to top end performance in trade."

I will have to look at the pipe and get the model to determine which I have...I would guess it is probably the torque pipe, as the bike does fall flat at higher rpm, but some of that could be due to incorrect jetting.

 

[jb_dallas]

Called FMF and I have the Gnarly torque pipe. I read that the stock main jet is 145, which I am sure everyone is aware. I will pull out the main jet and check...im assuming its stock.

What is everyones opinion on the RB Designs carb mod? Is it worth $165?

 

[reepicheep]

Lots of us on 200's want that torque pipe... maybe you can find somebody who doesn't have one yet, sell it to them, and find a used rev pipe for about the same price.

 

[jb_dallas]

The bike pulls like a tractor up to about 6000 rpm, then falls sort of flat. I am wondering about the performance of the torque pipe and a modified carb (RB Designs). Do most people that have the modded carb use the rev pipe? Or a cheaper less effective solution may be trying a 147 or 148 main jet.

 

[jb_dallas]

I suppose the KDX crowd views this thread as mundane...nevermind.

 

[reepicheep]

If you want a personal mechanic, there is one waiting for you at your local Kawasaki dealer for $80 or so per hour. It's money well spent if they can sort out things like jetting problems... their experience was hard won and valuable.

To fix your 220, sell your torque pipe to somebody with a 200 or the Eric Gorr 225 kit (my setup, working nice with the torque pipe) and get a rev pipe. I personally think the carb mods beyond jetting are dubious. I'm sure some people swear by them though. Boysen reeds seem to make a difference off the bottom, and are cheaper then Kawasaki reeds anyway. I rode a 220 with a Boyesen VBlock thingy, a Pro Circuit rev pipe, and it was a *very* nice running bike. My 200 (now 225) just has the torque pipe and boyesen reeds with the factory reed block. Once the jetting was right and the bike was broken in, it runs great and pulls hard.

To fix your jetting, you are going to have to buy a bunch of jets and start experimenting. It is quite a learning curve, but it is doable. For me the biggest learning was that jet effect is mainly relative to throttle position, not current RPM's. I dialed in the low speed jet first, then the high speed jet, then tuned the needle clip position. I used the FRP offroad recommendations as a starting point, and they were close.

Each bike in each location in each set of conditions will have a little bit different jetting to run right... so you will need a few jets laying around anyway.

Oh, and is that the stock piston in there? If so, get it out of there and put in a Wiseco... easy job. It's a grenade waiting to happen.

 

[jb_dallas]

Thanks for the reply, that was informative. I am concerned that trading my torque pipe for a rev pipe would decrease my bottom end power, which is where I need it the most. I have a WR426 with a few mods that is my power bike, but I am about 180 pounds and it is heavy for me in the technical, tight woods, so that is the purpose of the KDX.

I installed a 148 main jet (it had a stock 145) before my ride this weekend and the bike seemed to pull a little harder on top. I probably should buy a few sizes of pilots and experiment with clip position, although it seems that most run the stock clip position (3rd). I was hoping that someone had experience with a 220 and a torque pipe, but I am understanding that is not the most common combination. I dont care to spend $80 per hour at Kawasaki...I can dial in the bike with some time and patience. The experience at this forum does help. I may try the 607 reeds next.

 

[jb_dallas]

To answer your question, yes it has the stock piston, but it is a very low hour bike. What is the issue with the piston? With respect to longevity, I had always known KDXs to be the XRs of the 2 stroke world.

What clip position are you running on your carburetor?

 

[HRDROKN]

To answer your question, yes it has the stock piston, but it is a very low hour bike. What is the issue with the piston? With respect to longevity, I had always known KDXs to be the XRs of the 2 stroke world.

What clip position are you running on your carburetor?

The pistons come apart... causes a lot of unwanted grief.

The Gnarly woods pipe and the 220 combination literally has no overrev. I think most prefer the desert variety, although I like my woods setup just fine and got used to short shifting.

Go ahead and go larger on the main... you are probablly getting close.

:whoa:

 

[reepicheep]

The 200's are the bullet proof ones. The 220's are just as bullet proof, after the stock piston blows up and you replace it with a Weisco.

I thought it was an overstated risk when I was looking into it for my 200... then I helped a friend buy a 220. Granted it was a data point of 1, but my eyes opened when the seller of the bike was giving the history, and said 3 months after he bought it the piston let go and destroyed one engine case in the process, and he replaced it with a new case and steel sleeve and non factory piston, then rode the heck out of it for the next 8 years with no problems...

My 95 had a cracked skirt when I pulled it, but was still intact. But that bike was pretty much destroyed when I bought it and had to be completely rebuilt anyway. The fact that it was even running with so much wrong with it was a miracle.

 

[jb_dallas]

Damn, that is a big disappointment about the piston, I have never heard that. Luckily, its an easy job with minimal expense. Could you tell much of a performance upgrade over the factory piston, or is it just preventative maintenance?

 

[reepicheep]

Just preventative maintenance, especially on a 220. On a 200, you can bore it out before putting in the bigger piston and get a performance bump from the porting and displacement.

Proper jetting is the big performance booster for the KDX. I wouldn't be surprised to see a 20% improvement for "jetted right" over "jetted OK". I know that was for sure the case with my bike.

 

[Brian]

Keep in mind that there are likely tens of thousands of 220 riders who have never had problems. If it really would make you feel that much better it only takes $100 and an hour or two of your time to put a piston in...

 

[craig_enid]

I lost a piston on my first 220, but I had ignored A LOT of tell-tale signs that things were on the decline.
Jetting... play with it. Get a load of different sizes and try them all.
Once I had an 1/8th throttle rich spot I couldn't get sorted out, so I ordered a sudco needle that was one step lean at the spot I -by guess and by golly- thought was off. Seemed to work like a charm... for me.
Pipes... get both. Find out what YOU like, not what everyone else likes.

 

[jb_dallas]

Piston kits with gaskets are about $170...I will give it some thought. I would guess the bike has about 40 hours (original sprockets, chain, rotors, engine covers show very little wear), maybe I will change the piston in a year or so.

On the jetting topic, I think I will raise the needle one notch and see what that does.

 

[reepicheep]

You can also pull the head and jug as a unit (God bless two strokes) and inspect the piston, and reuse the base gasket (God bless two strokes). Nothing lost but a little time.

I did that and found a cracked skirt. Who knows how much $$ that saved me.

 

[jb_dallas]

Thats an idea, but if I spent my time doing that, I would probably just install the Wiseco piston when I had it torn down. I would guess it is like new inside...the bike is super clean.

 

[sr5bidder]

if the piston comes apart you would be in for a bit more than $170

might look something like this:
piston kit $170
cylinder repair replate $250-$350
or
cylinder sleeving $220-$250
rod kit $100
Main bearings $54
crank labor $60-$80
head cap machining $50


and set of cases from dealer $487
from ebay $200- $275


so if your cases make it cost would be around $800

if it eats your cases too best pricing would be around $900

the 220 seems like a pay me now or pay me later Bike

 

[jb_dallas]

SR5, that is a very ugly scenario. I didnt really plan on spending money on the bike right from the start. I will consider a piston replacement.

 

[sr5bidder]

sorry I had some spare time to look up the pricing and know the rest ( sleeving v.s plating repair)

you could look into a pro-x piston they are very good quality My catolog is from 08 and lists for $108
but it may be best to go with wiseco I had read that the pro x and stock may be the exact same piston


problem being that the skirt is designed to thin and prone to shatter

 

[jb_dallas]

The $170 was a complete Wiseco rebuild kit with piston, rings, pin, and gaskets. I dont hear much about the KDX200 having piston issues, I wonder why...they are very similiar in design. Why would Kawasaki use a thicker skirt for the 200 piston and a thinner skirt on the 220? If any difference, I would imagine the 200 having a lighter piston being a higher revving engine stock.

 

[sr5bidder]

well IMO the 220 was an after thought, not planned well and meant to use up the stock pile of parts at the factory meant for the 200 towards the end of production.

using the same crank as the 200 but a bigger piston, they may have made the piston thinner to keep the wieght the same as the 200's piston instead of messing with the crank halfs...you know for ballancing reasons

why bother for 20 more CC's other than to give the sales enough boost to clean out most of the production stock.

I wonder why...........