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KMX200 tuning?

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Dec 27, 2003
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#1
Hi, just wondering if any KDX200 riders have any tipps on the best ways to get a few more bhp from my 1988 Kawasaki KMX200. This is a street-trail bike, with a 2way KIPS,(no main ex port slide). i think the motor is based on the 86 KX125, (67mmx54.4mm)but very detuned, (30bhp) Im re-building the bike as a supermotard, but as the motor is apart, i want to make some modifications to improve performance, particully top end power, as it goes a bit flat after 8000rpm. Im going to get a performance pipe and silencer as the original one is damaged, im hoping that this will improve power, along with some mild porting work to the cylinder. Im going to use the V-Force reedcage for the KDX200 as its the same size reedblock as mine. Can i run a bit more compression if this is likely to help? Its 8.0;1 std, and i dont mind running 98RON gas. Also the Carb is a tiny VM26mm, and im sure that this is holding back my motor at high rpms. I need to retain an Autolube feed to the inlet rubber though, so should i have the VM bored to a larger size? or will a TM28-32mm carb fit. If i fitted the KDX200 intake, i could use the PWK35, but then i dont know how i could hook up and oil feed to it? Any advice would be great!
Cheers-Steve.
 

tedkxkdx

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#2
Steve I have a couple of questions and comments and don't take any offense to them.  I just want to give you my honest Joe-public response.

I knew two brothers who owned a kmx 125 and kmx200.  Both guys were very fast riders and pushed these bikes to their limits in stock form.  They were faster than my unsellable 6K+ KDX 200, and that can make you mad.

In super moto acceleration is important as well as stability.  The kmx is hard to get that ( the aforementioned guys were just lunatics with no fear) acceleration or stability.  The magazine TBM in the UK published a guide for dirt bikes and stated this.  Some of which may help you if you continue to make this bike a supermotard.

" 87-92 Big bore version of the 125 which makes a more capable all-rounder.  Though not as reliable as the 125 and when used hard off road had a propensity for boiling over.  Suspension could also feel pretty soggy by modern standards.  Occasionally the KIPS valve can give trouble, as can clutch and radiator.  200 also lumbered with the 17 inch rear wheel so many change with the 125 18' to improve off road tire choice.  kmx also suffered from indifferent build quality, and could be fragile off road.  Pads and discs wore out quickly but low seat height is more accessible for shorties than kdx.  Verdict: more tea vicar...?"

Does that sound good.  NO.  After you're done making it a super moto and go race some events and get hooked you may want to get a better more capable bike.  Who will you sell that kmx supermoto to?  Most kmx's in this country are being sold to people with a small budget.  People who are short are buying other brands of small four-stroke bikes for racing/riding.

Save yourself the effort on this old out dated bike and buy something more suited to super moto, where parts for that kind of racing are plentiful and aftermarket companies cater to.  The only place I know to get parts for kmx are breakers and the kawi dealer.

Sorry dude, want to buy a kdx built for Supercross?  Only 2000 more quid than the others for sale in the country.
 
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#3
Hey, thanks for your thoughts and valid points about my bike. Its nice to know that someone actually knows what a KMX200 is, as its less common than the KDX in many countries, or not sold at all. I can see that you would be right, about the limitations of my bike for competition use, and that the KDX is vastly superior off road, and for competition based on its taller better suspension, the KDX would make a better supermoto racer too. I however am only really looking for a machine to ride on road, or maybe on the occasional track, and im not considering competition use with the bike, or i would get a KTM or CCM. I just want a machine to ride well on the street, thats light and reasonably fast accelerating, so that i can have more fun in town/city, and be able to corner and brake faster than a bigger heavy sport bike. The KMX is std 30bhp/100kg, and im looking for say 35-38bhp/90-95kg. I would think the KMX would look great as a street supermotard, but am unsure about a few things. Firstly how to get a bit more bhp out of the motor, and secondly, how will the handling be affected by 17" wheels? What sort of brake and suspension mods would i need, (bigger front disc, and I thought about a KLR650 caliper and master cylinder) I guess that the forks can be re-built to make them stiffer, and firmer action. Id also like to use a fork brace to stop the forks flexing, as i dont have usd fork. The shock is easy, ill just have a replacment made to suit. Will going to 17" rims badly affect the steering geometry though?, and what sort of reduction in seat height can i expect, from the stock 865mm? As long as i can make the KMX handle quite well, and make the motor more lively, then i think it will make a better road bike than the KDX200 would. Its got full instruments, and turn signals, and i doubt that the KDX would be any faster even with road gearing. The KMX should run to 90mph+ with road gearing. If you think that i can improve my KMX and make it handle for road riding then im keen to try and make a motard out of it!
 

tedkxkdx

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#4
I would hate to ride a kmx at 90 mph. I know how you feel about doing a couple of things to your bike, I did them too. I just feel that you would be better off doing a minimum of things and not spending too much quid on it and then you feel that it is unsellable or when you do settle on selling you get so little for what you put into it. I just think since you will have to hodge podge so many of the parts for it, you will spend way more than what you could of had with another brand/bike.
 
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#5
I can understand where your coming from but, even if i decided that another bike would be better/easier to modify and get SM parts for, and also more sellable later on, id still have to sell my KMX first. I can spend about £1500 on my KMX, and then it should be a nice road bike. I know its not a proper competition tool, but its gotta be much better than a DT125R etc, and i would say maybe the next best thing to a CRM250, which is the bike i would have if i could afford it. I dont feel the KDX200SR would nessassarily make any better road legal SM bike than the KMX would, its far superior off road though. If i were to change then i would have to have a 2 stroke, so it leaves only the CRM250, or a handful of very rare other bikes that im unlikely to find spares easily for. (DT230 Lanza, KDX250SR, RMX250 etc) I nearly brought a KDX250SR but turned it down as, my kawasaki dealer would not be able to get spares for it, and that bike is very rare in the UK. I could go down to a 125cc and have a ready made SM bike like the Husky SM125, or KTM125SM, but again these bikes are rare, and a new one would cost around £3000. I do feel a sorted KMX200 could be a better machine to ride than say a Husky SM125, and probably a bit quicker also. Its good to get the opinion of others before starting with a project, but i think im going to stick to my guns and see what i can do with my KMX. Resale isnt a big consideration, as if i can get the bike well sorted for fast road use, im going to hang on to it indefinately!
 

tedkxkdx

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#6
Yes, if you are going 2-stroke, hold on to the kmx. There are few choices for the price range you are looking at. A crm 250 is a nice bike. I did not know about them when I purchased my UK kdx.
 
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#7
Keep your KMX125 and convert it to motard. There are lots of guys here using KMX, it's pipular here because it's really fast. can reach 140 kph easily. most guys here convert it to motard, i'll try to post some pics. They change the seats with a fabricated one to make it look like a KX. They just buy KX fenders and number plates then weld some nuts where you can mount the plastics onto. They also use the tank cover or shorud?? of the Kawasaki KX and mount it on the gas tank, i swear you'll think you're looking at a KX but it's actually a Kawasaki KMX125.

You wont notice unless you look at the engine and the fork is not upside down..

I attached a pic of KMX, offroad action. It can fly, they just hop it up.
 

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#10
I've been keeping eyes open for a KMX for quite some time now as an around town bike. I think it would be awesome to super moto one, and I look forward to your project. I hope you stick around and provide us with progress pictures and ride reports!

I think Ron Black (rb designs) would be a good person to talk to about carb and head mods if you're looking to add some grunt and top end to the bike. I know the overall engine design is similar to the KDX200, so some of the same mods that make the KDX rip could be used in the KMX. It is also possible that an aftermarket KDX pipe would fit, and add some all around power.