Why does the raptor use different jets from side to side? Doesnt all of the air fuel mixture all going in the same cylinder and getting fired by the same sparkplug?Two valves or one shouldnt make any difference should it? Its all going to end up in the same place anyway. Or am i missing some thing? later

 

Since my Raptor has yet to arrive, I can't claim any expert knowledge on them, but my understanding is that one carb feeds two of the valves and the other one feeds just one, which accounts for the fact that they each use different sized main jets.

 

Thats a handful for 2 carbs. j/k. A raptor has 5 valves and the right carb feeds 2 valves while the left carb feeds 1 valve. and there is 2 exhaust valves. Your right that all the gas and air goes into 1 cylinder but you need equal amounts of air and gas into each valve or ur engine will run poor. The right carb's main jet is 2 sizes bigger than the left so it can . Only the main is a different size.

 

I knew that!
I had five valves on the brain, I guess. I just got my shop manual today amd already have the Motion Pro twister and stainless steel skid. I wish I had a scoot to put them on Oh well it's supposed to be here this week.

 

I would like to Know what jet sizes to use with a K&N,GYT-R muffler at sea level.I may also add a big gun header or fmf header with that setup.

 

well, I finally got my Raptor today! I would suggest you try a 142 in #2 carb and 147 in #1 carb and to a test/plug read with a new plug to get an accurate reading. Depending on the plug color, you may have to go one side fatter on each carb at your elev. In the final analysis, only your own engine can tell you what it wants in air/fuel mix.

 

I HAVE WHITE BROS R4 AND FMF HEADER
with the flaps cut out of snokel
160,165 mains
27.5 pilots burning perfect
at sea level

 

No need to change header you wont gain anything!