04 YZ85 Jetting Problem Solved

[dune-addiction]

Problem - Stock jetting seemed too rich, spooge everywhere, tried every combination of leaning it out and created the Bwaaaaaaaaa off idle. No combination seemed to work. Only ran decent if the air screw was turned in all the way.

Solution - First, Yamaha factory installed the read cage upside down. They look symetrical on the outside but they're not on the inside. You will never get the jetting right with the read cage upside down. THE TAB ON THE READ CAGE MUST BE POINTED UP, NOT DOWN. Second, need larger pilot jet to help with low-end power and off-idle acceleration. Here's my setup now at 100 degrees in Phoenix and it rips:

Main: Stock 138
Pilot: 52 (stock is 45) May try 48 or 50
Jet needle: Stock 2nd Clip Position
Air Screw: Stock 2 turns out

 

[sodflyer]

After looking at your post lastnight I tore my son's bike apart looking for the things you listed. his 85 had everything correct on it, so I slapped it back together and rode it a little....tell you what...his bike has no bottom end what so ever so I put the main back in the stock position from where I had it at #2 from the top, now today I am reinstalling the stock jets from the ones I had in there that werwe the second to last on the leaner side according to the manual. I remember after first riding this bike 2 months ago it would pull a wheelie with ease up through third gear....now I have to work it. Jeff.