[homershere]

Hey guys, New Guy here...
I've been reading the forums for a while now and thought I should join in! I have an 03' Raptor 660 that has been worked a little before I bought it. It has a set of hot cams in it, a slip on fmf muffler and no air box lid. When I bought it the starter solenoid was bad and I killed 2 more till I wired it with a ford style solenoid. That issue got resolved. The issue I am having now is it backfires every now and then at idle but backfires bad when off the throttle and going down a hill. (when using the motor to slow you down). Could the idle screw be off or maybe jetting be wrong. I do have to say that it runs awesome and has a very snappy response when hitting the throttle. Any input would be appreciated.

 

[RaptorGirl]

Welcome to the forum :beerchug:

Your jetting is probably off...check your plug to see what color the tip is...If it's white it's lean (need to adjust , if it's black it's rich....some of the 660 guys can probably jump in here to help you out on specifics for jetting though. :thumb:

 

[homershere]

Thanks Raptor Girl,

I am open for suggestions. I have an extra set of carbs that I can play with the jetting or whatever and throw on to see if it works...

 

[homershere]

No other suggestions ??? Anyone???

 

[660RSE3]

sounds like you need larger pilot jets. if the previous owner didnt mess with the jetting i would go ahead and rejet completely.

 

[homershere]

Do you know what size jets are stock?

 

[bdc0923]

Do you know what size jets are stock?

Pretty sure the stock mains are 140 and 145, stock pilots are 22.5. Up the main jets to about 150 and 155 on mains and 25 on pilots, and 2 to 2 1/2 turns on the air fuel screw on bottom of carb. You should look into getting a VITOS jet kit they are like $50.

 

[homershere]

Thanks Bdc.... That's what I was looking for. All I needed was a direction to go in. I will look into that kit and see what happens...

 

[660RSE3]

ya i 2nd bdc on that VITOS jet kit, i have one they are great. they give you everything you need including new needles and better mixture screws. good luck!

 

[homershere]

Thanks 660.... I like what I'm hearing...

 

[homershere]

Hey Guys, I think I found the problem....
The left side carb intake boot is ripped across the bottom. I believe that is giving it to much air and creating a lean condition...

 

[homershere]

All fixed !! Brand new set of intake manifold boots and we're good to go...