My Raptor shoots flames out the back when I'm in neutral and rev it up high. Also if I'm at a higher RPM in a gear and let off the gas the exhaust "pops" sometimes as the motor winds down. Are these things bad? Do I need to adjust something? Am I too rich or lean?

I just don't want to hurt anything, if these things are acceptable I can live with them.

John

 

So what is happening if im correct, the machine is not burning all the gas so it goes into the exhaust, which in turn the fumes catch fire which causes the flame. This is what causes the "popping" sound as well. When you rev it, it shoots gas in the pipe, then the fumes ignite and cause the popping. This is not a good thing at all, example gas catches fire in small space = boom.

 

These things are not acceptable, and are typically a sign of lean jetting.

BTW, you should not be revving up the engine high in neutral.

 

In the winter my Alba pipe with the open tip did that on my warrior, it did not ever hurt anything and it ran good.

 

Yeah, if you have an open pipe without an arrestor when the bike back fires it will really back fire...

 

so if it is running too lean, do I turn the mixture screw? If yes, then which way? Or do I put a larger size jet it? If I remember right I already put a size larger than what was recommended. So is it really just a matter of turning the mixture screw?

Thank you

 

If its backfiring that violently and its doing it on decelleration its probably your mains not your a/f screws. What is your current jetting and airbox setup?

 

I have the proflow kit on the raptor with K&N and no lid. So the air is pretty much free to do as it wishes. I believe (I don't remember for sure) that I used a 155 main????? I may be mistaken, I believe that it was the largest one that may kit came with. I do remember that I went a couple sizes larger than what was recommended for my elevation.

What is the difference between adjusting the mixture screw and having to rejet??

 

The mixture screw controls the air-to-fuel ratio. One way allows more air in, the other more fuel.

Rejetting changes the amount of fuel the engine gets. I'm guessing by what you've said that you need to jet down because you are rich. After this happens, can you remove the seat and smell gas?

Check your plug to see if you're rich or lean.

 

I really dont think that he is too rich with a 150/155 main unless he lives in the clouds. That's only 2 sizes larger than stock and he has removed his airbox lid.