First of all i would like to say that im new with these forums, but im been reading alot of them over the couple of weeks.Anyway, i bought a '02 raptor about 2 months ago. THe first day i went riding It was doing ok,(60 degree Weather). Whenever it started cooling off to about 40 degrees i noticed it started backfirng and shooting flames. I waited till we got 60/70 degree weather again but it still didnt quit backfiring, it wasn't as bad but on deccelaration it would pop. Any ideas?

 

If it is popping on decel, I believe that means you are running too rich, you need to re-jet to a smaller size! When I was jetting mine, which was a pain in the A.. mine would pop while accelerating and just lacked a bunch of power, I jetted a few sizes up and changed needles and it worked out good!

 

If its popping on decel, up your pilot jet. Stock is 22.5, go to 25 or even 27.5. Also, do you know what your current jetting is at? With the mods you have listed, I would say you should be about 165/170 or 170/175 with the needle on the third clip. Someone more knowledgable might say different, but I think that is a good starting point. Does your bike seem to have decent power ten all of a sudden fall flat on its face? Mine did that and I was jetted to lean (too small on the mains) I uped the mains to LRD specs and it is a different bike. Hope this helps.

-Brandon

 

Oh yeah, I should add that I am talking about DynoJet main jets when I say 165/170 and 170/175. Stock mikuni jets will be slightly different. I'm using an LRD needle, and regular mikuni pilot jets.

-Brandon

 

just the opposite

you are lean on the pilot jet

if you are 3 turns out on your air/fuel screws,,,,you will need to bump them to a 25 like rookie said

 

165/170 sounds like mikuni jets

dynojet would be somewhere like 146/148

 

Alright thanks, But is it lean or rich? Could it hurt it if i just kept runnin it? And if it does what could happen?

 

you are lean (not enough fuel) on the Pilot curcuit if it is backfiring on deceleration

pilot jet controls how much fuel is delivered at idle and just off idle

 

Also, Whats your opinion about the D-A-J( Dial a Jet)?

 

i would only get one of those if i was going from sea level to 12,000' on a regular basis