Join Date: Oct 2001
Location: Southern Minnesota
I have a 2000 XC700SP. *I'm running into a similar issue with the 1371 needles, Boost bootle, and power paks. *With the 38 pilots it seems a little too lean down low, I couldn't get the idle right. *So I changed the pilots to 40s. *Now it idles fine, but it's a little too rich. *I'm going to try the 1370 needles with the 38 pilots next, as soon as my dealer gets them in.
As for the power paks, someone correct me if I'm wrong, but I think the theory is that it increases the air velocity moving through the carbs at different throttle openings. *They basically divide the opening (to the engine side of the slides) into three. *When the slide is 1/3 way up, the air is kept in the bottom 1/3 of this opening, this way the air doesn't have to fill up the larger opening before moving on. *At from 1/3 - 2/3 air moves through the bottom two openings, etc.
It works like water in a pipe. *If you're pushing water through a 1/4" pipe that expands to 1/2" the water will slow down when it enters the 1/2" pipe. *If you keep the pipe size the same, the velocity will stay the same.
Then again, I may be way off. *All I know is they do seem to work. *$60 worth of performance increase, but probably not much more.
Beware the lollipop of mediocrity. Lick it once and you suck forever.
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'02 MXZ 800
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