Maintenance & Technical > KX250 / KX125
KX250 Woods Conversion
Dan_AKAL:
Mike,
I think I can understand how moving the reeds back can help with flow. By getting them further away from the engine there is less of an arc for the air to make as it enters the crank case. I know they are pointed down at an angle but I still can understand how it would improve the direction of air flow as well as allow the reeds to work a little easier. All of this adding up to less work the engine does to get the air in.
Most folks it seems are pretty happy with Scotts steering dampeners. I looked at the WER but I think that I like the Scotts better.
The pipe I'll run for the time being. Maybe after it gets bashed up some I might think of a Gnarly. However, will probably make a call to PC to see what might be available for my bike.
Thanks Again,
Dan
KaTooMer:
Dan - just a few thoughts after spending the last year (most of it, anyway) in the woods on my '03 KX250. Many of the aftermarket mods available for MX bikes seem to be designed to make them work better on the track. I've not tried any Pro Circuit exhaust products, but my impression is that they attempt to improve what most MX'ers claim is a comparatively weaker top end than the other MX bikes out there. For a woods guy like me, I don't need any more top end on my KX. To smooth out the power, I'd look closer at FMF products, particularly the Gnarly pipe since it's designed for woods use. The Turbine Core or "Q" silencers will probably also help smooth things out. I just picked up a used "Q" on eBay...haven't put it on yet but judging by the size of that thing, it just HAS to tame the hit.
I haven't tried out any aftermarket reeds/blocks, again because my impression is that they add power where I don't need it. As for flywheel weight, I'm a believer. I rode it one time without any weight and that was it. You do give up some of the snappy throttle response with more weight on the flywheel, but in the woods I haven't missed it.
One thing I've been liking recently is the Braking over-sized front rotor. It was another eBay purchase...pretty amazing how much stopping power it gives (and the front brake was good to begin with).
mikesmith:
As far as Pro Circuit,they have the MX pipe that you have now,and the platnium2 which is like the FMF gnarley pipe.Correct me if Im wrong,but after the fuel leaves the reeds its stored in the inlet track/crankcase under slight preassue from the underside of the piston coming down,then the fuel leaves the crankcase to transfer ports to the cylinder to fire,theres more of fuel/air available with the spacer.
Dan_AKAL:
A couple of days ago I didn?t have any idea what a reed spacer might do. Now after a lot of research I think that I am getting an idea of what is going on here. By installing a spacer between the reeds and the crankcase a larger volumetric area is available in the case. The gain is pretty large considering the size of the case. Not only does it gain the area of the spacer but also moves the reed cage further out of the case. In addition to gaining the area the aerodynamics of the mixture flow is improved. Without a spacer when the reeds open the first thing the air mix would hit would be the cylinder wall. I would think this would vary from one engine design to the next and I expect that a great deal of research has gone into how reeds are placed and the design of the intake manifold. Anyway, by moving the reeds further back with a spacer the airflow into the case isn?t quite as restricted. What are the benefits and where would they be noticed? Without first hand experience I can?t determine this. One thing that comes to mind quickly is that the longer air and fuel are mixed together the better the saturation. By increasing the area the mixture would remain in a suspended state longer thereby increasing saturation. The saturation gain I believe would result in better overall engine efficiency. This would probably be noticed more so at lower speeds and immediately off idle. However, I could understand how it would be seen throughout the entire engine RPM range. I can?t believe that any manufacturer would size their cases where there would be a marginal volumetric area. Carb size, intake manifold size, and case size would play a very big part in this. However, I can see the benefits of the larger volume of air mix in the engine. Maxima has a very good diagram at their web site of oil migration through a 2 stroke engine. Have a look. It is very informative.
As for the pipe and silencer I am somewhat limited on availability for a 99 KX250. It is sort of stay with The PC stuff I have or get a Gnarly. Since I already have the PC stuff and it works I?ll probably give it an honest try. If I am unhappy then I?ll look at the Gnarly.
Thanks again for all of the info. I?m sure there will be more questions before I get finished with this.
Dan
teamgreen500:
Later model cylinders fit the 99-00 motor with astounding results. Team Green has built motors using your bottom end and '02 cylinders. This makes a motor that's unbelievable from SX to X-Country.
The best help for your scoot is in the susupension department. You need to get the spring-rates and dampening right for your "Off-Road" conditions.
Good luck,
Manny
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