Jetting probs !!!

[steveatv3]

400ex

I am having serious jetting problems, i am running a stock carb with 170 main jet, 42 pilot and the needle the 3rd clip from top.

I have absolutly no bottom or midrange, it feels like riding a 2stroke dirtbike, it will not start using the electric starter i have to compression it. and its not running right on the top end either it feels like stock, it has good compression and was recently rebuilt. any advice is appreciated!

Mods:
Sparks x-6 full system
K&N filter
440 engine
HotCam stage 2
Port and polish

[skippy]

fcr carb will help

[steveatv3]

right now i dont have a FCR carb i have a Mikuni carb though im not sure what size and i took that off beczuse i know nothing about jetting on that.

[buster369]

it sounds like u are running way way way to lean. Run it wide open take the plug out and look at it.? Is it black(rich), white(lean), or tan and good?

[MIKE400EX]

Also make sure the cam timing is correct, sounds like it may be retarded (a tooth).

[steveatv3]

the plug is BLACK as black can be! and i think my cam is ok, would it do this with bent valves?

[qr3379]

then ur either burnin oil or its runnin to rich. try a smaller jet if u have one and if it it still black then oil it burnin

[cals400ex]

with the stock carb try:

keihin 158 mainjet, 4th needle clip position, 42 pilot jet, 2.75 turns out from lightly seated on the fuel screw.

make sure your throttle cable is adjusted properly so you don't have a ton of slack in it. change the plug, don't just clean it off. make sure your filter is good and clean too.

[buster369]

if its burnin oil it could be the rings or the problem i just had was bad valve seals, the spring on one of them broke.

[MIKE400EX]

It wouldn't be bent valves if you had good compression. What was the compression reading?

[steveatv3]

im suppose to have 12.5 :1 compression.

[steveatv3]

Thanks guys i will give everything a try!!!!:D

[cals400ex]

yeah, give it a try and see how it works. by the way, i don't think mike was talking about the compression ratio.

[MIKE400EX]

Cals right, I meant if you had a (psi) reading from a compression check gage. Have you tried that Steve? Could give you an indication of a valve or ring problem. Did it run any better before the rebuild, and did they change anything besides a freshen up?

[steveatv3]

i knew what u meant i didnt do a psi reading on it, but it was bored to a 440, new cam, port polish, heavy duty springs

so im trying to get the carb to match the engine