wr 400 cutting out

I have a 99 wr 400 and it seems to be cutting out. If I am I just idling and and twist the throtle fast it will cut out. I can live with that. My new problem is that it is doing it even when riding. If I want to get it on out of a corner or etc. it tends to do it also. Any ideas??

look at the right hand side of your carb. look at the rubber boot covering a chromed rod. see the rocker arm it gets pushed down by and it's pivot point. undo that nut, pull the black plastic arm forwardto you. turn the rod sideways for now and tighten back up.

you now have no APJ. the bike will be excellent without it if the rest of your jetting is good.


If it was fine before, but now getting bad.

First things first -

put in a new spark plug

clean and reoil your airfilter

Try Taffy's suggestion as well.

Has it got hotter were you live? Use one of your spare's kit main jets in going to a leaner jet.

Jorg3- does this only happen when you crack the throttle wide open from idle or low revs (when moving slowly or going around a corner)?

Taffy- I have had a similar problem and have never been able to completely cure it-yet.. I have tried your previous jetting specs and disconnected the APJ. It felt nice but the dieing became worse. With the APJ connected it was improved but not perfect. Yesterday I played with needle and fuel screw settings which did not help. Today I am going to play with the main and MAJ. Then I will work on the PJ. I am not convinced that it is an over-rich problem. I have run rich settings before and lost the dieing but made the mid-range fat.

I have been able to make compromise jetting specs but they have never been perfect.

See what happens I suppose.


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