Maintenance & Technical > KX500 Original

High Rev Closed Throttle

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petro:
Thanks for the guidance guys.... All is fixed and she sounds and runs f**kn awesome. The richer pilot and needle position helped solve part of problem. The other half of the problem was dicovered when I removed the gas tank and discovered that the PO routed the throttle cable all crazy likely getting pinched between tank and frame. Has me wondering what the hell this guy was thinking between the carb settings which were way off and the little attentions to detail that were looked over. Scary!!!!!!!!!!!!!!!!!! 

Happy Thanksgiving

Ride Fast

KX5MOD:
Let us know how you make out against your buddies 450 now  8-)
I have a sick modded K5 that just dusts 450's like a joke, & a bone stock one that beats them everytime as well.....second gear starts---to well past top out.

Polar-Bus:

--- Quote from: petro on November 23, 2009, 12:04:50 PM ---Thanks for the guidance guys.... All is fixed and she sounds and runs f**kn awesome. The richer pilot and needle position helped solve part of problem. The other half of the problem was dicovered when I removed the gas tank and discovered that the PO routed the throttle cable all crazy likely getting pinched between tank and frame. Has me wondering what the hell this guy was thinking between the carb settings which were way off and the little attentions to detail that were looked over. Scary!!!!!!!!!!!!!!!!!! 

Happy Thanksgiving

Ride Fast

--- End quote ---

Pilot jetting plays a pretty substantial role in overall jetting, and the reason being is that no matter what tune you have the pilot circut, that tune also affects the entire carb jetting spectrum as well. Pilot jetting mainly is noticable from "closed" throttle to 1/4 throttle. But the pilot jet is still feeding fuel even at 3/4 throttle. I like to adjust my engine for a temporary idle, and just listen to the idle quality. If I hear the idle slowly rise, this is lean, and you need to richen the pilot. If you have a decent idle, and you hear the engine rpm's slow, and the engine sounds rough, this is the engine loading up and your a bit rich. This is my personal crude method, but it's worked for me for years. Sometimes you can achieve results juts by adjusting the air screw, but other times a jet change is required. You generally want your air screw to be able to maintain a clean idle between 1.5 and 2.5 CCW from seated.  If you are out of that adjustment range on the air screw, that means you need a corrective pilot jet change. You can read for days about 2 stroke jetting, but your best jetting tool is a keen ear, and feel. Takes much trial and error practice. (I still after 22 years don't have jetting perfect, but I get my bikes very close)

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