stock bike running lean from the factory ?

do these come from the factory running lean i read another thread and the guy had similar issue as i did and said it might be due to the bike running lean? if so is there an easy way to run richer. i read they made it run lean to meet certain spa standards but i don't know how true that is

kpla51 wrote:

do these come from the factory running lean i read another thread and the guy had similar issue as i did and said it might be due to the bike running lean? if so is there an easy way to run richer. i read they made it run lean to meet certain spa standards but i don't know how true that is

Yep. That's the commonly stated reality.

Which is why the second people start adding things like free flowing exhausts, and airbox mods we all highly recommend they immediately buy an efi programmer so they don't run the risk of going too lean.


Remember - "leaner is meaner"......but too lean =

All highway vehicles in the US have to pass EPA emission standards to be legal on the road. So, all come from the factory with lean fuel ratios to accommodate that requirement. Not so with true track or dirt only bikes.

Yes they will be lean to meet EPA requirements but certainly not dangerously lean otherwise Yamaha would insist on an EFI programmer
when fitting the GYTR slip on.

If you just running a slip on with flapper mod I wouldn't worry about it.

If you want more power and not just noise the programmer is the way to go.

I'm happy to leave mine stock for now, maybe just to the flapper mod while I work on my bike control. :)

Stock (motor) rocks.