I just installed a sparks exhaust on my 04 Raptor. I have not even got it out of my shop yet, but I did start it just to hear it run and man does it sound good!!!!!! I've got a question though just after it ran just for a minute or so the head pipe turned a yellow/orange color, is this normal for a stainless steal head pipe? I jetted with dyno jet kit and also changed the pilots to 27.5 I went with 148 and 150 mains If any of you have this same pipe please give me some input on jetting and fuel/air screw settings

 

If you got rid of the air box lid, I would run 155/160...from 0-3000ft

 

I don't have a lot of experience with dynojets, but that sounds a little low to me....

 

How will I tell if it is lean I know you get that stumble on top end if you get to rich, but what is the tell tell signs of being to lean?

 

your jetting should be really close.........I too ran the dyno jet kit with my sparks pipe.........

and I also have a stainless pipe..........it becomes quite ugly when it gets hot.......it is called blueing........

 

I agree with BigScary... your current jetting should be close.

I ran 146/148 (dynojet kit) with the Sparks full system, and ProFlow adapter /with K&N Lid On.

It performed better than any other piped Raptor Ive ever seen in my life.

 

My sparks pipe glows even with my FCRs. I think it's normal to see that in dim light, it'll even do it when it's jetted really fat on the bottom.

 

148/150 with pilot jet 27.5 is the recommended Dynojet sizes from Sparks themselves. It is the setting used for a raptor with sparks exhaust, K&N, with pro flow adaptor and no lid on airbox, at sea level. If you are at a higher altitude, closed lid or stock air cleaner you need to go lower jet sizes.

I have a stock raptor with a Sparks X6 ceramic exhaust and a L&A adaptor with a big K&N. I am at 4700ft above sea level. The dyno indicated that I have to use dynojet sizes 175/180 and a 25 pilot jet. The L&A adaptor flows tons more air that the stock airbox and Pro flow adaptor, hence the much bigger jet sizes.

My raptor is now running 150 155 dynojets and needle in clip 4 from the top of the needle. I am getting a air to fuel mixture of about 13:1 up to 6200 RPM, then it goes way lean (15:1 @ 7050 RPM) and the bike looses power. I still have to test this, but like I said. I need to run about 175 / 180 Dynojet sizes and the needle should be in clip 1 or 2 from the top. I will test it on the dyno next week. It seems I need to run about 13.5:1 ratio of fuel and air up to 6200 RPM for best power and torque. Past 6200 I need to go way rich to give the raptor lots of fuel to make power. The ratio seems to be about 11.5:1 for best power and torque. If I run less fuel at high RPM I loose HP and torque. With the wrong jetting my raptor is now pushing out 49.5 HP at 7000 RPM and max torque is 56Nm @ 6000 RPM. With correct jetting I am sure I will get 50 HP maybe slightly more.

Dynojet does not cater for the sparks and L&A adaptor, so please do not try and run their recommended jets if you have the same setup as me. If you are running up a dune at max RPM, you might run the risk of running to lean and causing damage.

Please make the effort and test your bikes on a dyno. Make sure they test the air and fuel ratio while the bike is running thru the RPM. Doing jetting by checking the plug colour is not going to give you the best power, and like I have noticed, you might be running lean at higher PRM and causing problems for the motor. The plug will give you an average color. My bike’s plug is dark brown and I know I am running way lean at higher than 6200 RPM. So don’t trust that plug color.

I have the dyno reports comparing the 150/155 jets to a setup running 165/170 jets with the needle in clip number 4. It shows you exactly what you loose and gain by changing the jets.