KX250 Mods / More Trail Worthy

[Nickbob43]

I have a 2002 KX250 bone stock, nothing done to it, except some jetting and needle settings.

I want to use the bike more for trail riding and do a few hare scrambles this year.

Can you guys give me a few detailed ideas on where I should start, and what mods to make so this bike will be more trail riding, hare scramble useable.

Don't get me wrong, I know the bike is a full bread motocrosser, but their has to be a few things I can do.

Like gearing, what front and rear sprockets sizes are recommended from stock?

Suspension settings?

Flywheel weight?

If you can, give me some details on these things. I'll greatly appreciate it.

Thanks

Nick

 

[DWreck]

1. Revalve suspension. I thought mine was good before but I love it now.

2. Gearing. This is kind of up to you and where you ride. Do you feel like you are between gears. I run one extra tooth on the back and am pretty happy with it.

3. Flywheel weight. I don't use one but would probably be faster if I did.

4. Steering damper. They are expensive but are very nice to have.

And don't forget the hand guards.

 

[KXtrailrider]

I run a 13oz flywheel weight, a large gas tank, lower gearing, hand gaurds and a skid plate. If you don't revalve your suspension back your compression clickers off. For gearing I am using a 2002 trans 3rd 4th and 5th and a 1998 1st and 2nd with stock sprockets, gives it a much lower first 2 gears. I only trail ride for fun. I also have a 310 kit on it but again just for fun. The first thing I recomend is lower gearing and a flywheel weight. Good luck and have fun. Ed

 

[jeffh]

Take a look at www.john-stichnoth.com/GreenMachine.html
You should find plenty of good info.

 

[Nickbob43]

What about plugging up the airbox and routing hoses somewhere else? I've seen people talking about that.

I was riding the other day and it was pretty muddy and I got water and mud in my airbox because the airbox hole is rite by the rear wheel.

 

[bikepilot]

I rivet'd some rubber from an old inntertube so its closed at the back on open at the front. Will still draw some air in and drain water out, but not much water or mud will make its way in the botom. Seems to work out pretty well.

I'm currently racing a CR250R in harescrambles. Its stock except for handlbars (CR-mini low with cycra's) and a spark arrestor (so I can do practice rides in then natl forrest). I turned the clickers out on the forks and shocks and the suspension is decent, though still a tad stiff. I'm on the light end of the spectrium so I'm going to try softer springs, then perhaps re-valve. Still, its totally competitve in the B class as is. Flywheel weights can help if you have traction issues or tend to get worn out/beat up quickly.

Gearing totally depends on the course. I typically use the stock gearing, but if its going to have some very high speed sections an extra tooth on the front can be a big advantage.

I'd love a steering damper, that's on the list, but $$$.

Have fun, ride and race - don't worry too much if your bike isn't totally tricked out unless your trying to go pro it will not really matter. Before college (2000) I was racing a 93' KX250 in B class harescrambles and doing very well. At the A level and down its not really the bike that will make the difference provided its basically working correctly.

 

[Britt Boyette]

What about plugging up the airbox and routing hoses somewhere else? I've seen people talking about that.

I was riding the other day and it was pretty muddy and I got water and mud in my airbox because the airbox hole is rite by the rear wheel.

You can try to make the airbox more water proof but it may be a waste of time. The KX airbox was never intended to deal with large amounts of water and mud. If I were looking for tips on making one waterproof, I'd check out a KDX200 airbox for design tips. That's a great airbox for wet riding.

 

[Woodsquest]

Here is a link to some photos of my '02 KX250 woods bike.

CLICK HERE FOR PHOTOS

I have lots of mods to make it quick in the woods and enduro ready. Probably the most significant is the auto clutch. Gearing just isn't an issue with it. I can start from a dead stop in 1st or 3rd, the auto clutch will do the work needed to get me rolling. Nice when you're in trouble on a steep hill and can't shift or work the clutch.
There's CR high bend bars, bark busters, head lights, Procircuit pipe, IMS pegs, Carbon fiber pipe guard, fork guards, rear brake guard, ignition cover. Tri-metal rear sprocket, 12 tooth CS sproket, o-ring chain. IMS M5B rear tire and Dunlop 739F front tire, IMS 3.7 gallon fuel tank, tall seat foam, VForceIII reed set-up, home-made kickstand, FMF TurbineCoreII spark arrester, CR style routed front brake line, Stainless steel brake lines on front and rear, Hand operated rear brake where the clutch lever used to be, skid plate, TAG triple clamps, Scotts dampner, KTM style front fender and tool box, front brake guard, Devol radiator guards, etc...

 

[Nickbob43]

So what happens when I'm out trail riding and I need to ride throung a 2 or 3 foot deep mud creek?

There has to be a solution to the KX250's airbox

What about guys that are doing hare scrambles on moto cross bikes, how do they make sure do water gets in the airbox.

Water and mud get in there too easy, doesn't seem rite to me

 

[Britt Boyette]

You go and find another spot for crossing that's 1 to 1 1/2 foot deep and go slow. This is also what the Pro's do. I've even seen some get off there bikes and walk along beside them to get them through deeper sections. If the water is over your pegs or boots, go slow. Anything else and you could be asking for it. Also, if you ever drop you bike into the water, don't try to restart it without first removing the spark plug. Then kick it a few times to flush out the water. Reinstall the plug and kick it over. If you don't do this, you could cause major engine damage.

 

[Bandit9]

I run an 02 KX250 in Enduros. What I have done about the airbox issue is to completely seal off the bottom hole with some foam. I have also used duct tape on that top clear flap that is right behind the fuel tank. Dirt still gets in there, but not nearly as much. Main thing I do is use a shop vac to suck out all the loose dirt and and a rag to wipe every thing down every time I change my filter. I use those filter skins too. When it is dusty, I just pull on the tab sticking out the back of my seat and to pull off the filter skin. Main thing though, is to be diligent in changing your filter and cleaning out the air box. I have never really had any issues from sucking water or dirt from the air box into my motor. I pull the carb once a year and clean it out, but I have never really found a bunch of stuff in there. I don't think this should be a major concern.
As far as gearing goes, I have experimented with 12/49, 13/50,51 and 14/49. In the end, all of these produced gaps for me in certain situations leaving me back at the stock 13/49. It seems to be the best for all around riding.

Other modifications I have done:
Suspension revalve is an absolute must.
Set up handlebar position to where you can stand up comfortably. This may require taller bend bars, clamps that move bar position forward.
handguards
Scott's steering stabilizer
Skid plate
Rear disc rotor guard
Steahly 11 oz flywheel weight
IMS 3.1 gal fuel tank
Gnarly pipe with Turbinecore II Spark Arrestor
Motor work to smooth the hit and make the power better suited for tight technical woods work.

 

[Britt Boyette]

Bandit9 has a good setup going there and you could use this as an excellent blueprint to build your bike.
One thing to pay close attention to is the FMF Gnarly pipe. I use a Fatty on mine but a Gnarly is a better choice because it uses a thicker gauge of metal to withstand the trail better.

As for the gearing, I also ended up using the stock gear ratios although I might go one higher for tight woods but the stock ratio seems to cover all the bases for me as well.

As for engine work, both my 04's only have aftermarket pipes and one has a 11oz flywheel weight, that's all. The 04's have a powerband that suits the woods way better than the motocross track. It matches my riding style very well which is a first. Most bikes I ever had, had to have something done to the engine to make them do what I wanted. If I were doing motocross, I would go to a 4 stroke KX450F. Awesome bike!

 

[Nickbob43]

Thanks a million guys, I'm new to the Dirtbiking scene and it seams all of you are pointing me in the rite direction.

About the Pipe modifications you guys are doing with a spark arrestor. My bike still has the stock pipe on it. Does the stock muffler not have a spark arrestor?

 

[KXtrailrider]

The stock muffler does not have a spark arrestor in it. You have to use an aftermarket muffler with a spark arrestor in it or an addon like a sparkey(clamps to your stock muffler). I use a Pro Circuit spark arrestor.

 

[kshackleton]

I have changed my gearing to 12/54 teeth front/rear....love that gearing!

13 oz flywheel weight...spark arrestor muffler...."bark buster" aluminum hand guards....softened the suspension damping.

I am still looking for an FMF Gnarly pipe on ****....

 

[Bandit9]

Just slap a spark arrested slip on silencer on your stock pipe. Then when the stock pipe gets trashed, which will be soon, then get a thicker pipe. I really liked the way the stock pipe worked. It is just too thin to hold up to the abuse of woods riding. The Gnarly, is just that. Gnarly. It is very thick and hasn't dinged or bent once in about a year of enduros. It increased the low end yank though, almost too much for my tastes. But I like not having to mash the stocker back into place or blow the dents out of the pipe after every ride. 2 thumbs up on the Gnarly. Pro Circuit has a thick pipe too, I just never used it.

 

[KXtrailrider]

BTW I am now using the Gnarly pipe too. It is the thickest strongest pipe out there. Being thicker it is harder to blow the dents out though, I have dented mine, but it is the best choice for a trail pipe.

 

[Nickbob43]

BTW I am now using the Gnarly pipe too. It is the thickest strongest pipe out there. Being thicker it is harder to blow the dents out though, I have dented mine, but it is the best choice for a trail pipe.

If I slap a spark arrestor on the stock pipe, is that a Kawasaki part or aftermarket? Where do I get it? To run a hare scramble do I usually have to have the spark arrester? I'm AMA district 17..

Where do I get the 13oz flywheel weight and what is entailed in installing that? Does the stator have to be removed?

 

[kshackleton]

The weight is available from Steahly....installation is a cakewalk. The weight replaces the nut that holds on the flywheel [remove the nut, spin on the weight], torqued to spec and secured with set-screws. The kit also comes with a spacer that moves the cover out about 1/4" for the necessary clearance. I took my sweet time and I was all done in 20 minutes.

 

[kshackleton]

I got my muffler from FMF....fits right on stock pipe....5 minutes max. to swap.

 

[KXtrailrider]

All spark arrester's are aftermarket. the sparkey is an add on to the stock muffler the others are full mufflers. Any dirtbike catalog has them. As kshackleton said a Steahly flywheel weight, I use a 13oz. If you get a spark arrestor muffler get the biggest, quietest you can. We all need to be as quiet as we can be.

 

[Nickbob43]

Where do I get the sparky that goes on the Stock Muffler?

Sorry about all the questions guys, all of you have been a big help and I greatly appreciate it.

Nick

 

[DWreck]

Where do I get the sparky that goes on the Stock Muffler?

Nick

I have one that I might part with. I bought it last year and used it for a week in Colorado. I don't need it for anything I do around here and will probably have another bike by the time I need one again. Let me know if you are interested.

 

[motonuts]

I race local desert races in calif. and have a 98 kx250.
IMS tank 3.2gal. scotts stabilizer, 8oz. flywheel weight for traction, hand guards, revalved suspension, 18"rear wheel.
These I think are a necessity in the desert. I have other mods but that's just for my likes, tall seat, oversized grips, etc.
REMEMBER, IT'S EXPENSIVE ALL AT ONCE!!!!
BUY SLOWLY AND ACCUMULATE...