wheres the pilot jet

ok,,,i have a 98 yz just reduced the squirt from 3 seconds to <.5 seconds

now it pops and bangs when i shut the throttle off.

i assume this is the result of the pilot jet being to weak?

ive turned the fuel screw out a full turn and it now sits at about 2 1/4 turns out.

so my question is

where on the carb will i find the pilot jet?

how much of a jump should i make in jet size.?

also should i raise the needle at all?

the bike runs hot at low revs [ again i assume this is a pilot jet issue?]

thanks in advance

On the bottom of the carb, undo that 17mm plug, its recessed in a hole about 3/4 inch up directly next to the main jet. The main jet is a 6mm hex, the pilot requires a skinny flat head screwdriver.

Yak; I think the 400's have a bottom plug that requires a 14mm wrench. Keihin wsied up on later years and put the 17mm plug for easier access.

Why did you make the ap squirt so little? When you change your jetting, you should only go one size at a time. All the symtoms you describe are from a lean pilot. I don't think you need to mess with the needle.

Changing the pump squirt should not cause the condition you describe. While your correct in your diagnosis, Im betting you have a piece of something in the pilot jet, and just need to clean it out.

The pilot screw range is between 3/4 and 2 full turns out. If you cant get it right in that range, you should change out the pilot.

But I doubt that you should have to change it now. Unless you changed something else too.


what throttle opening range does the pilot jet effect?

all i know is it was squirting a hell of a lot of neat fuel in for a long time, surely this kinda fuel flooding would mask any week jetting??

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