The raptor is currently being rebuilt, and i have a few questions about the jetting with these mods... 1mm bore with a 11:1 weisco racing piston, stage 2 racing cam, spring kit, Big gun exhaust, stock airfilter. ive got the dyno jet kit put in right now, but the question im at is what size main jets and do i need to change the pilots? i think elevation is 5000, but ill have to get back to you on that, just need the help

 

First, you need a pro-flo (or comparable), the stock set-up is a joke at best. After that...toss the lid, call dyno-jet and get jets from 170 down. Start with 170 and work your way down until the machine runs crisp. You will need too lean the needles a notch from recommended as well because of turbulence.

 

If you insist on running the lid, 148-150 mains will be a good place too start....your engine will tell you what it wants....keep an eye on your spark plug. If you are unsure of the process, have an experienced tuner take care of this for you.

 

Well i have the standard dyno jet kit right now, the quad is at my friends house (who is bassicly rebuilding it for me) but i am helping him out. At 1st we were just rejetting the carb and putting big gun pipes on it, so we jetted the carb to the pipes, then after we found out the sleeve and the piston were a little scored, we descided to bore with the 11:1 piston. then we talked to people and they said it wont increase power that much unless u replace the cam, so we descided to go big on the cam. And we got new springs for the cam, then we remembered, "Hmm, i bet we need to rejet" we will probably run it with the lid off, does the pro flo make a diference? i thought stock with the lid off would do fine, from what ive heard. So you just suggest start at 170 and work down until it runs right??? theres no real science to this?

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Lol im rebuilding mine because tranny died, 2nd gear had a piece snap off and conviently travel through the tranny and my case [img]i/expressions/face-icon-small-smile.gif[/img] GG me

 

You can not use the stock filter with the lid off, the lid holds the filter in place. Some have used screws to hold the stock one in place, but I still think it's a crappy set up. The pro flow probably flows more but more importantly it seals better and does'nt require you to use the lid.

 

The major difference is the pipe, cam, and increased compression as far as jetting is concerned. No, there is no REAL EXACT science too jetting....only ballpark opinions as too what guys are running in similar set-ups. Every engine is a tad different and sometimes needs different jetting if everything is supposed too be the same. We have guys with your set-up using Dyno-jet mains and needles running 150-155 (with your set-up).....another running 155-160. I am running dyno-jet needles and 165-167.5 mikuni mains on my mild set-up. Again, start high and work your way down....better safe than sorry.