kx 250 jetting

Joined
Sep 24, 2003
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#1
Hello all,
working on a "91"kx250 with what I beleive is jetting problems.
It has a new top end(sleeved back to stock). Stock reed's(lifted slightly). Dyna comp pipe and slilencer. Stock pilot"55" stock main
"175" jets in a stock kehin. It has a little snap out of the hole but
then drop's and each gear it has a little snap then drops. It's like the mid and the top just are'nt there. The top end only has a couple of hour's on it, so it's not compression. It do'es smoke like it's running rich when you get into it, but act's like it ain't getting enough fuel. Am I missing something here? Any help would be appreciated.
 
Joined
Sep 18, 2001
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#2
just try going 1 leaner on the main and see if you are going in the right direction. If it gets better, then you can look at the plug and make other changes until it is fixed. Your aftermarket pipe is maybe why the stock jetting isn't going to work.
 
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Sep 24, 2003
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#3
I tried a "172" main jet and it still did the same. I talked to some mechanic's at my local kawasaki dealer and they said to try between "165" to "155" main and "50" to "48" pilot and stay on the "2nd" groove from the top on the needle. Although I showed them the manual(from kawasaki not clymer), where it said "175" main and "55" pilot, they insisted the manual was wrong. Hmmm. I'll try their sugestion this evening, they said the same thing about the pipe. Thanx for the info! let ya know what happens
 
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Sep 24, 2003
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#4
Well I tried the "160","158","155" main jet's and the "50","48" pilot jet's. Look's like the "155" main and the "48" pilot works the best. I moved the timing to the advance and to the retard there was a little change but not drastic(except to the retard), but I set it back at stock till I get all this worked out. Do you think think that these jet size's are a little small or within the normal range? A buddy of mine is runing a rm250 and he is runing a "172" main don't know what pilot, but same groove on the needle and same pwk 38mm carb. I know I should just take the word of the mechanics at kawasaki, but this just don't seem right, and feels like there is still more power to gain both on top and bottom(top seem's like it need's another gear). And I still think the bottom end should yank a lot harder. The mid (2nd,3rd gear) trie's to stand the bike up(not that I mind), but that seem's like an odd power curve to me. Don't know what I'm missing,( maybe I should just try shooting dope to it on the bottom end, gotta love nitro!)
Thanx for any help.