I have a 07 400ex i just got a hmf sport series slip on and a unif filter with no airbox lid....what should i do with my carb? where should i start at with the jetting? im locatd in kentucky!

 

jetting is all about exparamentation. but first, you <u>deffinatly</u> need to jet up. more air means you will run lean, unless you increas fuel! take an afternoon and exparament with diffirent main jets. start with one size larger, then run the following test.

warm up engine, put a new plug in ($3.00 big woop), run your mechine all the way threw the gears and when your at top of 5th gear pull in the clutch and hit the kill switch. when you stop pull the plug and look at the color.

white = lean, bigger jet
black = rich, smaller jet
ideal= marshmallow brown color.

just keep trying diffirent jet sizes until you get a brown color, then you have reached your ideal fuel/air mix and theoredically max power for your mods

 

my main is a 148 stock....what is the pilot stock? should i just change the main or the pilot also? i have ridden just a bit around the yard since adding the pipe and the only thing noticed is a lil bit of popping on decelaration. please help... what should i start at a 150 or 152? ive seen that a lot of ppl recommend a 155.

 

poping on decell is a BIG indicator or of running lean. its all about jetting for YOUR conditions, YOUR area, and YOUR mechine. there is no automatic best-jet, if you want to get all the power from your mechine you have to find which jet is best. buy a jet kit, like dynojet, and you will have a full selection of jets. bigger isnt automatically better. too big of a main jet will dump gas in the engine an rob you of power. get a jet kit and cross refrence the dynojet #'s with mikuni or khein#'s. start with the smallest provided and move up from there.

 

changing only the main jet ? or the pilot jet as well?

 

just main. if you had an idol problem then i would suggest messing with the pilot.

 

alright, idle is good...just need to get a few different mains....think i could pick them up at a local shop? thanks for your help cherokee

 

MY 07 400EX HAS HMF SLIPPIE AIR BOX VENTS CARB SPACER.I HAVE A 42 PILOT HELPS A LOT ON COLD STARTS. 155 MAIN DYNO JETS. I LIVE IN ILLINOIS 565 ABOVE SEA LEVEL.STOCK PILOT IS 38.AND DYNO JETS DIFFER FROM OTHER JETS A 155 DYNO IS NOT THE SAME SIZE AS A STOCK JET 155.AND YOU MAY HAVE TO ADJUST YOUR AIR MIXTURE SCREW 2 1/2 TO 3 1/2 TURNS OUT

 

where is the fuel screw located?

 

BOTTOM OF CARB MINE IS D SHAPED SOME ARENT DYNOJET GIVES YOU A TOOL TO ADJUST IT