Drz 400s Jetting Specs

HI guys,

I need to jet a drz400s with yoshi full system, open airbox and k&n filter. Stock carb, right now we were at 155, but still lean. I would like to know what main jet and pilot I should get for him. thanks a lot.

what needle? what is the exact size of the intake opening? why do you say its lean?

stock needle (5DH37-1) , 2x4 opening on the top of the airbox and the plug was white.

the plug will always look like that with modern fuel.

how does it pull at high rpm?

Not to hijack, but it sounds like you've got a similar setup to me.

I just picked up an '07 SM with the full yoshi system and K&N air filter. The airbox has not been modified yet.

The previous owner says it was jetted properly, but it pops on deceleration, which I thought was a sign of being lean. Yes? No?

I need to mod the airbox and pop off the carb to see what's in there.


a slight pop on decel is normal.

Thanks Eddie,

He said the pipe was installed by the dealer and jetting done there, so I had hoped it was okay.

It runs like a scalded dog, but I wondered about the pilot circuit based on the popping. I'll still follow the thread to see if the pilot circuit is done right.


hi Eddy,

the bike ran great but seemed to lack throttle response a little bit. The bike popped on deceleration but it pulled nicely.

the stock needle is lean on the straight diameter to begin with.

to make it 100% right you need a JD jet kit.

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