450r carb jetting thread #15796

[Muddinguy]

I know search there's tons of threads yadda yadda But when it comes to jetting im at a total loss of knowledge !

I'm running a 440 motor..
Gona freshen up the motor with a new jug with HD studs new piston got a 450r carb.. all that good **** to make it pretty.

anyhow here's my specs..

440 jug 12.5: Wiseco piston
Stg 2 hot cam
white bro's CDI (not sure on model #)
P.C. T-4 exh
Open air box with an outerwear over the top (NOT THE LID !) and a K&N

The choke is still installed on the carb im assuming cause the lever is there.. but i dont see anything in the bore

our elevation is 902'

I'm looking for a straight answer hopefully.. Ive heard of a kit when you can put a fuel nozzle in the intake and just increase the fuel amounts til it runs right ?? then base your jets off that. or is the nozzle a permanent thing ?

[JOHNDOE83]

my 440, with the same type of mod's, at sea level, use's a 50 pilot jet, 220 main jet, and the needle I never touched.

Our mod's are almost the same, the 220 might be a lil big for you, there's a guy on here with a 416ex that runs a 205 main jet.

Start with a big jet like a 205 and see if it start's to stutter on the topend, if it does the main jet is rich, if not go bigger till it stutter's then go down in size till it stop's.

Then that cover's the main jet, if it backfire's on de accleration or pops through the carb get a bigger pilot jet, if it surge's on accleration in mid rpm's adjust your needle higher, most of the time the needle's ok where it is but sometime's you need to move it up or down.

this is just a baseline for jetting if you want to get technical do a plug chop.....www.jetsrus.com go to the FAQs section and read all about jetting.