Yz426f Jetting question

[ricky_arthur]

I'm sure this has been covered, but I read for several hours and did not find an answer. I'm at 6500ft elevation. the bike was way rich with a 168 main jet so I put in a 150 MJ. My question is on the air/fuel screw. The jetting is much better but I think still too rich. But with the bike warm and idling I can bottom out the screw and the idle raises I back it out just till the RPM's drop back down and I'm still rich.

I think i need a smaller pilot jet. but it is not reacting the way it says it should. ie. the idle should lower as I get further away from the best spot. It

Any suggestions

Its a 2001 YZ426f Thanks


Ricky

 

[Rich Rohrich]

But with the bike warm and idling I can bottom out the screw and the idle raises I back it out just till the RPM's drop back down and I'm still rich.

I think i need a smaller pilot jet.

As you turn the "fuel screw" (it's not an air screw) in you are leaning out the pilot circuit so it makes sense that the rpm "might" come up. Put in a leaner pilot an bring the fuel screw to 1.5 turns out and adjust from there. You can't hurt the bike by going too lean on the pilot jet, worst case if it's too lean is it might change it's starting behavior or introduce a slight bog just off closed throttle.

 

[ricky_arthur]

Thanks

I went from a 42 to 40 pilot jet. very little if any difference. Should I go to a 38pj?

 

[Rich Rohrich]

You won't hurt it with the leaner pilot so it's worth a try,

 

[steve.emma]

it could also be worth checking the choke plunger is seating properly and not leaking gas past it at idle causing a rich idle condition. this could explain why the fuel mixture screw is not leaning it out enough to drop rpm or stall.

 

[ricky_arthur]

I put in the 38 PJ and 145 MJ. Clip in 6th position. Bottom and middle are very good bog still exists in WOT. I'm gonna pick up the next size down in MJ 140 ish and hope to have it dialed in.

Next I need to order a 13 front and 51 rear sprocket to make it a bit more trail friendly. any thought on that gearing set up?


Ricky