Can you list your elevation, mods and specs for your YFZ with a hmf system. Im at 1000feet with lid on and trying to figure it out. Now Im at 172 main, 45 pilot 2 turns out lid on and my plug is whitish. Accordind to other posts I have read either Im to rich or alot of others are to lean??? I have read alot of people at lower elevations with lid off running like 168 mains???

 

If your plug is a whitish color then you are still lean. I just have a hard time believing with the elevation of 1000ft and running a 172 main jet with the air box lid on you still running lean.

I jetted a YFZ450 at sealevel using 172 main 48 pilot and a ProDesign air filter kit. Plug reading was a tan color using Super unleaded. If you are using VP Fuels then it will be hard to get a plug color.

 

GYT-r air filter, NCVQneedle on the 4th, HMF full system lid on 172 main and it is alittle white almost ashey color. I did have the seat off when testing though.