Maintenance & Technical > KX250 / KX125
My bike is a pig. It eats gas and spark plugs.
eprovenzano:
Posted on: August 21, 2006, 12:39:11 PMPosted by: Arigato
Insert Quote Since I run mine is sand, I'm running a B9. Non-resistor, If you have a pace-maker, stand back!
As Arigato pointed out, depending on riding style you may need to adjust how hot of a plug you run. He's in the dessert WFO running a 9. If I'm running a track I run an 8 (because I'm too old and slow to keep the throttle pinned), but if I'm in the woods busting trails, I'll drop to a 7. My jetting is a little rich, (because that's how I like it) but I've only fouled 1 plug in 2 years. Another problem can be your pre-mix. Find a pre-mix brand you like, and stick with it. Switching brands can wreck havoc on jetting. Jet properly, and have fun.
FuriouSly:
Get the float set first. A little fuel spilling out when leaning the bike over a bit is OK. Most racers have the float set to give a little more fuel in the bowl than stock, more supply for wide open throttle (WOT) and when laying the bike over heavy in turns. Some even purchase a bigger aftermarket bowl or mod the stock one for modified motors using lots of fuel.
Put in a BR8E(G)(medium duty-fine wire nickle) or BR8E(V)(race duty-fine wire gold platinum), instead of an BR9E(S)(standard duty-copper core). This will give you a better quality plug to work with and less fowling with longer duty life. The lower number is hotter and larger number is cooler. Dunes 9, track 8, woods 7, so to speak.
Then start working on the jetting. The airscrew really only helps the pilot system (idle to 1/8 throttle) and up to 1/4 throttle where you are just getting on the needle. So see where your main jet is at first (WOT running good with throttle chop and a plug check) and work back the two steps (needle clip and pilot jet-air screw). Of course this is a quick overview of the steps. Start at the top.
Sly
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