ok, heres the deal..i just got my fully redone 416 back with the web cam, piston, headwork, etc etc, and the shop keep the jet i had in and just messed with the airscrew/feul mixture and said it was running perfect with a 152 main......i see peeps having 165's and 175's etc etc.....i have the air box off and he said this may have took the place of the bigger jet size...what do you all think...it runs really good, snappy, no bogging or back firing....what will help going to a bigger jet? thanks

 

Jesus!, I am running a 165 main and a 45 pilot with a very similar setup. I kept my airbox and cut a 4" hole in the lid. Before I did the 416 kit, I ran a 40 pilot and a 160 main with port/polish internals and xr400 headgasket. Now I am running a 416 with xr400 cam and 11 to 1 je piston. I am running a Gabe modified style stock exhaust.

 

152 does sound small. I'm also running 45 pilot with a 165 main on my 440. If it is running good leave it alone, but be careful of running to lean. Watch for red pipes.

 

yea my pipes where kinda glowing a lil.....should i try a 160, thats the biggest jet i have left...it came from a k&n power up kit.....it runs fast as hell...cant wait to run with a raptor or banshee.....it seems this thing has a powerband now....i smack it in third and it about leaves me on my a#$......anyway, thanks for the help, anymore suggestions would be helpfull......

 

well i just put that 160 in, and all i have to say is wow....no glowing red pipes, no bogging or smoking, no hesitations, when i smack the throttle and do wheelies it's still smooth as can be...as soon as i put it in, without even warming it up, and its cold here, it fired 2nd try...AWESOME.,,..runs like a bat out of hell, and i feel allot better and more comfortable knowing i have a bigger jet closer to everyone elses......

 

I believe that the K&N jet are not the same size as Keihin jets, that is a 160 K&N might be equal to a 152 Keihin.

Try getting a hold of a Kiehin 160, 165 and maybe even a 170...go as large as you can until it bogs then back off one unit for the cold and 2 units if its warm (50°f or above). Plug readings will not work well with oxygenated fuels if you're using them.

I do use race gas (Phillips 66 110 octane) and find that a Kiehin 45 pilot, Kiehin 165, main pilot screw 3.25 turns out from seat, 6-1" uni-filterered holes in air box, snorkle removed and stock air filter pulls the 440 ahead of experienced ridden stock Raptors and DS650's from start to finish in 1/8th mile of sand.

99'440, 12:1 JE, flow port, 450/451 cam, hardened rockers, xr250 cdi, 16-38 gearing, modified stock head pipe with a WB-R4 silencer.