300ex tuning

I have 95 300ex its .40 over bore wiesco 11:1 piston four stroke tech cam and rockers, fmf power core four exhaust, stock carb with k@n jet kit needle 118 main jet stock pilot and needle jet. ever since i did the mods its run like crap. The plug says it is lean so what size jet do you all think i should try. also since i went from a 114 to a 118 it misses midrange in the throttle

118 is way to lean,be carefull you might of damaged your piston with the lean of jetting,a 300ex fully modified with stock carb runs a 140main and a 42 pilot,,,i would try with a 140 and work down to the lowest 128,and a 40 pilot

i have a full exhust,k&n and i have a 128,and 42 pilot

why dont you get a k&n stage 3 jet kit for 50.00

[R-Crazy]

if your plug says your running too lean YOUR RUNNING TOO LEAN. try just lowering the clip on you needle.

dave

he has the stock carb,stock main is 122,he has a 118,,thats lean,not the needle...the main and pilot would give inducation he is lean,,,go with a pilot 42 and a 135 main,bet you it runs better,,go with the 140 with a 2" hole in air box

[43atv]

your motor is a carbon copy of mine and i am running a 130 in mine and it runs fantastic.

with the stock carb 128-135 highest,depending on elevation-temp-and if you have the air box lid on or off,also the pilots basic range jumps from a 38stock to a 40-42.i had a 132 in to start,ran to rich 128 was perfect for me..

[01_300ex]

i have an 11:1 piston, and a t4 pro circuit comp pipe and no air box lid. a K&N jet kit and air filter. And my 300 is cutting out at the top of the 1,2, and 3rd gear, every since the piston was put in. I've tried different jets and stuff but it still does it. It was to rich with a 128mj, and it was brown on the plug with a 118. But even with the 118 it still does it. WHY?

did you break in your bike properly,you could be blowing by.
-when you start your bike does it need the choke?
-when you mean cut out,it hesitates or bogs down and doesnt clear out?
-try this set-up

put a 128 main,lid on with air box,and a 42 pilot.

for it to be too rich with a 128,is wierd.
what grade of gas do you run?who installed the kit,,the better you explain it to me the better i can help you,iam a motorcycle tech.. also what plug and check all wire and electric connections.

[01_300ex]

with my K&N jet kit i think it came with one pilot jet or maybe not one at all, i cant remember.If it did then what jet # is it.

40-42 pilot

[01_300ex]

i went to a 42pilot jet and it got better, i also unscrewed the air/fuel mixture screw and that also helped. BUT, it still does it in nuetral, and close to when you hit the rev limiter. What else should i try.Also, its like im getting more fuel than air in it.

[01_300ex]

i also have a 14th sproket and 11:1 piston

run open air box lid,set you air screw 1 and 1/2 out,then adjust idle

go down a jet..or two on the main,,what is plug color now run a colder plug like a 9

[330exracer]

IF IM NOT MISTAKEN DON'T U HAVE TO RUN A 50/50 MIX OF RACE AND PUMP FOR A 11.1.

[01_300ex]

yes you do

he better be,or he has just wasted his top-end and time..

[quadfamily]

Wesley,
Here's what I would do. 42 pilot, 135 main and lower the clip on the needle one notch. Also make sure you are reading the plug correctly. You look at the porcelain and the electrode when you take the reading. If your porcelain is white or very light in color you are definately lean. The porcelain should be tan when you have the jetting right. Don't worry about the outer diameter on the inside of the plug(the metal part). That will always be black in color. Use a magnifying glass with some really good lighting to look at the porcelain. If you see little tiny dots that are shiny like silver, that is your piston and you have already done damage to your engine. Good luck!

[2K1 300EX]

Go to www.FMFracing.com and it will tell what jets you need.