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KDX MX Mods

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Posted by: buck972---------------------

Hi There
Can any one tell me if you can upgrade a KDX 200 (97) to a 220 by fitting the barrel off a 220 ? will they fit?Or is there an upgrade kit if so is it worth it ???


Posted by: NSPHIL---------------------

It will fit but I can not remember if the case porting is the same so I do not know if it will work.
Some would consider mounting a 220 to a 200 (post '95) to be a downgrade. The porting in the two are different and many say the 200 is more powerful and capable. I have considered trying a 200 cylinder on my 220 if someone could confirm that it works, just as a comparison. Of course the stock 220 carb is junk and the test would be best conducted with a 35mm (200 stock) or Rb'd airstryker.


Posted by: duke---------------------

To satisfy my curiosity, may I ask what would be the purpose? I take it from your posting you have some intention of making the bike more suitable for MX track exscursions. If so, I think an easier and more succesful attempt would be to simply incorporate the basic pipe/carb/reed modifications


Posted by: Yamadad---------------------

My understanding is that you can modify the 200 bore to become a 220 by boring it only. Fredette racing does it all of the time. I'm sure someone down under could do it too.

BTW, I like the 220 better than the 200, but to each their own.


Posted by: adam728---------------------

Is your plan to make the KDX more competitive for motocross? If so, save all the money you were going to put into the KDX and put it towards a used motocrosser. The KDX is just so far behind the times that it can't really be made competitive, especially running in the 250 class. If you insist on using it, throw on a pipe and silencer, throw away the airbox lid, get it jetted properly, and turn all your focus towards suspension. Don't worry about more power, the suspension can't keep up with it on a rough track anyway.

I race the occasional MX on my KDX, the suspension holds me back much more than the fact that I am down 10-15 hp from the other bikes (cept on the start, that's where power matters). My bike is piped, ported, bored carb, all that good stuff. It's the suspension that makes it non-moto material more than anything.


Posted by: kmccune---------------------

If you have a real natural terrain track near you, the hp will be more of an issue then the suspension. The power and suspension mods couldn't hurt though.


Posted by: duke---------------------

I suggest you do your own search of the various threads on this forum wherein discussions about racing MX on KDX is the theme and draw your own conclusions. In general you will find that for a true old school type of venue, something you are more apt to find being hosted by a vintage club, an upgraded KDX in the vet/senior classes about c level is ok. An occasional practice romp on a slightly more modern course wouldn't be a problem, especially if you are just trying to really hone your turning skills, and/or getting used to going fast amongst traffic. Any real intent to chase points with a local sanctioning organization would best be pursued aboard an MX bike of some sort, be it 2 or 4 stroke, 125, 250 or open. There are some bikes within the MX species that are easier to ride then others. Again do your research here on the Dirtrider.net forum; its one of the most authoritative and detailed of all sites


Posted by: buck972---------------------

G day , Just to clear up a few things the mod in question is just to see if it is a viable option or not so thankyou for the replys ,as I only paid $500 for it ( and I got called all sorts or things by my mates for getting a bargain like that ) and it's only used for playing on rides with mates I have removed all the road requirements as listed : side stand , head light ,tail light, all indicators , frame cut back to just behind the silencer mounting point , electrics stripped back minimal ( just enough to run ), coolant recovery bottle removed and in addition I have fitted a pair of Renthal fat bars & grips , 05 KX number plate , I have already rebuilt the rear shock which was very easy and I will be fitting more apprporiate fork springs , a pro curcit pipe and maybe a V-Force reed box and a KX brake master cylinder with all the mods this bike only weighs around 90 KG and will be lots of fun for a long time any other performance suggestions are very welcome. ps sorry about the spelling


Posted by: adam728---------------------

Quote:
Originally Posted by buck972
with all the mods this bike only weighs around 90 KG


Have you actually weighed it? 90kg = 198 pounds, and there's no way a KDX is going to get that light without major, major mods (like a new frame and lots of Ti and carbon fiber).

You didn't mention a silencer, that would be another way to drop a good chunk of weight. Adding some weight in the form of a skid plate is always a good thing, especially if you play in rocky terrain.


Posted by: 19Brendan81---------------------

Buck, I am about to get my bike taken out to 240cc. There is a mob in QLD that do it, if you are going to tear down and assemble yourself they will sleeve the cylinder and send it back to you. Here are the prices I was quoted.

piston kit $274.30
big bore sleeve $285.45
gasket set $58.65
labour to fit sleeve $165.00

Of course you also need head work and jetting to finish the job. But once done properly the bike will go like a rat up a drainpipe. I am keen to buy your kickstand, what do you want for it?

Brendan


Posted by: buck972---------------------

Hi there , Brendan sorry I dont have the stand as it wasn't on it when i got the bike but I am shure you would be able to pick one up at a wreckers in your local area ( ? ) also can you give me the name and details of the mob in QLD .
Adam, when I say around 90 kgs thats a rough estimate but as a bike new weighs 225 lbs , 198 is not that unatainable , shurely at some stage I will put it on a set of scales and post it and the silencer fitted already is a pro-curcuit which is light , either way the point of my statement is to say it is very light more like a 125 , after riding a 99 CR250 it's a feather weight and great fun


Posted by: 19Brendan81---------------------

No worries mate, there should be one floating around here somewhere. The mob is called Serco Motorsport, heres how you can contact them. I emailed them and a guy called Ray Weekes got straight back to me.

SERCO PTY. LTD. 34 Veronica Street
Capalaba, Qld. 4157
AUSTRALIA
Contact one of our sales representatives on :
Phone: 07 3823 3833
Fax: 07 3823 3611
Free Fax Order Line: 1 800 625 356
E-mail to sales@serco.com.au



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