need help with carb!!!!!!

johng212004 · #1 (**permalink**) 06-30-2005

got a 91 lt250 bored 40 over, port and polished, head is milled to 18cc, paul turner pipe, keihn 39mm carb, brand new stator. i cant get it to run right. what needle, pilot and main would you guys recommend. im in nj.. around 90-100 degrees with alot of humidity so i dont know where to start bc it was running ok a few weeks ago when it was 60-70 out. its bogging hard... not idling by itself... it wouldnt stay runnin yestarday when i took the choke off. please help... been getting work done to this quad little by little over the past 4 months and i just wanna ride and not worry about it blowin up. thanks

johng212004 · #2 (**permalink**) 06-30-2005

oh yea... i know i have a 170 or 175 main jet in it... kinda small for all the work i have done right

91LT250R · #3 (**permalink**) 07-01-2005

I'm not an experienced carb tuner, so I can't give you numbers. You can start by telling us what you're running in your carb now, though.

MaineExport · #4 (**permalink**) 07-01-2005

well, if it was running fine at 60-70 degrees (that's a pretty radical assumption, but it's all you've given us to work with)... and you haven't changed ANYTHING since then, you need to go down a jet size or two. Theory being; warmer air is LESS oxygen dense which means the charge is getting less oxygen now than it did with cooler (more dense) air. So, you pull back the amount of fuel in the charge by dropping the main. The only way to really tell is to check the plug and work from there. Keep dropping down jets one at a time until it's tan-ish... not black or clear. If it's already clear (lean) then it wasn't running right before OR something else has gone wrong in the mean time that is causing your problems.

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johng212004 · #5 (**permalink**) 07-03-2005

i think i have a 175 i there now... very hot and humid out tho... im thinkn bc of the size of the carb i need to run smaller jets right?... just really wanted to know about the pilot and needle and work from there.... someone please help

sblt500r · #6 (**permalink**) 07-04-2005

if it won't idle without the choke your pilot jet is to small. with the choke open your feeding it more gas so with a bigger pilot it would let it idle without the choke.