1998-99 Yamaha YZF R1 + Kehin 41 FCR (TPS Question)

[deadbanana0717]

"Change the main jets up two sizes richer, drop the needles one posistion and re-dyno would be my advice"


What do you guys think?

[slowbird]

"Change the main jets up two sizes richer, drop the needles one posistion and re-dyno would be my advice"


What do you guys think?

Maybe only 1 size larger???

Won't going up a size in the main jet make the lower portion of your powerband (45mph-80mph) even richer?

My 96 YZF600 racebike would only run on 3 cyl when I got it.
Took it to Platinum Powersports for a complete carb rebuild and tune up.

He welded an O2 bung and ran wideband on the bike real time while tuning it.

Runs very strong now....passes YZF750s and GSXR 750s on the straights even.

X2 for Donald at Platinum

[deadbanana0717]

Actually Donalds a great man! he was giving me pointers on my situation and that was quoted from him ...

I suppose his thoughts on the UP 2 on main jets and droping needle 1 should offset the lower end, but still richen the upper.

Kinda makes sense in my crazy mind

[slowbird]

If that's what Donalds said than I'd give it a shot.

I'd like to know the theory in how going up 2 sizes on the main and dropping the needles down 1 will offset both the super rich low-end and uber-lean top end.

Not because I don't beleive, but because I wish to learn.

[deadbanana0717]

I'm guessing its gonna shift it to the right a bit and hopefulyy bring the AF closer to 13 on low and upper... anyone wanna take a stab at how it may look?

GTAM illegal betting ?

[deadbanana0717]

If that's what Donalds said than I'd give it a shot.

I'd like to know the theory in how going up 2 sizes on the main and dropping the needles down 1 will offset both the super rich low-end and uber-lean top end.

Not because I don't beleive, but because I wish to learn.

I am no expert, but this is what I tell my self to make me feel better =)
do you concur?

Needles - 1.
I guess for instant WOT Dyno tuning, even dropping the needle 1 probably wont Lean out the bottom richness.. probably wont offset the effects. :S ... but for actual street riding roling on or even aggressively to the throttle through the 2-4K RPM band, would probably help ridability.

Main Jets +2
Lean + Fuel = better AF... makes sense to me =)

[toysareforboys]

I'm guessing its gonna shift it to the right a bit and hopefulyy bring the AF closer to 13 on low and upper... anyone wanna take a stab at how it may look?

I sure hope it doesn't look like your drawing, I'd want the AFR to stay much closer to 13:1 (i.e. the dashed line). Your R1 be thursty, we need to keep her around the dotted line or slightly below (12.8 )

-Jamie M.

[deadbanana0717]

Hey Guys, I was just thinking about this and Wouldn't raising the float height solve this problem?