03 660 carb help

[CarGuy7a]

my buddy's raptor was popping and backfiring seriously bad. i told him it sounded like the pilot jets were plugged. so we worked on it this weekend and sure enough they were plugged with gunk. we cleaned the carbs all up and she fired right up.

now what it's doin is when it's idling it the rpm's stumble around and then after a few minutes it will just die. so i'm thinking the fuel screws need adjusting. i believe he still has the stock size pilots. also his reverse light is blinking (i think from just having to have the idle up so far for it to run) and the headers were glowing and the cooling fan kicked on. and this was on a night were it was only like 60 degrees out. sounds like lean idle conditions to me.

now the thing i need help on. i noticed that these carbs are jetted totally different. one carb is richer than the other carb. so i looked at an OEM parts list and noticed that this is normal from the factory. ok.

so do the fuel screws have to be adjusted accordingly? one richer than the other? and how many turns out should i set them at?

here's his mods.
K&N filter.
rejetted from the dealer he got it from don't know what brand jets but definately richer than stock jets.
White Brothers R4 full exhaust.

sorry for the long thread but any help is appreciated.

[CarGuy7a]

anyone?

[QuadManiac]

If it's stock, start them both at about 2 1/2 turns out.

Check the carb to intake boots carefully. If they aren't mounted well and the clamps real tight, air can be getting in through small leaks and causing the idle probs you are describing.

One way to tell is to spray carb cleaner all around the boots while idling. If the idle speed changes while spraying, you have a leak.


Good Luck!

[CarGuy7a]

thanx for the info. i'm pretty sure the boots are all good i didn't notice any cracks or anything when we took it apart and they were pretty tight. we'll check it out anyways.

i'm leaning more towards the fuel screws seeing is how he's not had it adjusted since he got the quad new in 03. or never had the carbs off and cleaned until now.

[dunerider07]

I had a similar problem with mine, the plunger/slide for the choke mechanism was stuck in the open position. The internal spring had actually rusted, therefore not allowing the slide to close. Replaced spring, cleaned, and reinstalled carb, runs perfect. Hope this helps