Jetting Recommendations Please - 02 YZ426

Can someone please recommend some jetting specs?

The settings below were decent when i was living at sea level, but i recently moved to 3500ft elevation and just did the BK Mod with .5 sec squirt. It was at around 3 sec squirt. I will be testing it in a few days. I am yet to start it up yet after i did the BK Mod the other day.

Two Questions:

1. What settings below should i change due to the BK Mod?

2. What settings below should i change due to the elevation change?

Thanks for any help.

Model: 2002 YZ426

Timing: YZ

Main Jet: 162 (stock)

Pilot Jet: 42 (stock)

Starter Jet: 72? (stock)

Leak: ?

Fuel Screw: Zip Ty: 1.5 turns out

Air Box: No Lid

Pipe/Muffler: Stock

Altitude: was at sea level, then just moved up to 3500-5500ft

Temp: 30-70F

Humidity: <20%

Theoretically, a 4200 ft increase in altitude would require you to lean your jetting by a factor of about .96, which would mean a 155 main and a 40 pilot. (Don't fiddle with the starter jet until there's some proof you need to. Your carb has no leak jet)

However, what I suggest you do is try the bike as is first. YZ426's had a rep for being lean on delivery, and you may find it runs really well just as it is, or perhaps doesn't need as much correction as the charts would indicate.

xnofriendsx sorry to hi jack your thread...

grayracer I'm hoping you can help me out with my jetting issues also? I have an '06 YZ450F and I am located in the San Francisco Bay Area. I replaced the jets with the FMF kit. Main jet is 150 and Pilot Jet 48, went 2 turns out on the fuel mixture screw and the have the needle clip at the # 4 groove from the top. The problem I am experiencing is it still backfires when I let off the throttle and sometimes doesn't idle that good. Any suggestions? Thanks for the help!


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