Gone to taffy jetting-still have a midrange bog!


I went for a good 2 days trail riding on the weekend with the following settings,


EMM pos 4

158 main/162maj

The bike feels like it is running the best since I've owned it.

The bottom end is as crisp as ever and nice and snappy, the hillclimbing torque right off idle is awesome, almost impossible to stall on big narly rocky hills.

Midrange still feels strong and the top end is almost unusable due to my rear tyre getting close to needing replacement and the silly amounts of power being produced up there, the yz timing definately gave me a good boost up top.

HOWEVER-I still ocasionally get a bit of a missfire/bog/hiccup when I have to snap it open really quickly to lift the front over a log or washout etc. It only happens occasionally but usually at the most inappropriate time.

It feels like if I snap it open to about a quarter throttle or just try to do little snap wheelies when I,m going slow, its fine, but when I have a bit more speed up and have to give it a quick panic induced 1/2 to 3/4 handful to clear a ditch or washout is when it tends to misbehave.

Is it possible to get these things jetted so my right hand doesn't have to do everything in slow motion. If I am smooth or a little bit slower with the throttle then everything is fine but I am used to riding 2 strokes and never had a problem with quick changes in throttle openings like I seem to be having with the big WR.

I think I will need to have a bit more of a play with the needle pos or maybe even the main jet to get rid off this small but annoying problem.

I havent done anything to my air cut valve at all and was wondering if this could be causing anything like what I am experiencing.

Any ideas guys???



it won't be your ACV.

it could well be your MJ and needle combo. try playing like you say. go back up to 160MJ and drop the needle and if it's too much put a .5mm washer underneath to raise it half a clip.

it could also be your pipe. don't forget that whoever designed the pipe did it withstd jetting.

you've just got to play.


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