A/F ratio vs jet size

[bumper]

Ok, all you guys that put your bikes on a dyno, on average changing one jet size changed you air fuel ratio by......how much? I know its not going to by the same for every motor, pipes and engine mods will effect it, but it should be able to be used as a ball park figure.

 

[Traumahawk]

On my bike going up 1 jet size brought the A/F ratio down .15. I went from 150 mains to 155's ( so .15 plus .15 = .3), my A/F went from 13.9 down to 13.6.

 

[maleko89]

On my bike going up 1 jet size brought the A/F ratio down .15. I went from 150 mains to 155's ( so .15 plus .15 = .3), my A/F went from 13.9 down to 13.6.

Geesh, man...can't you be any more accurate?

:biglaugh:

Mark

 

[blaxmax]

Am i misreading or is 150 to 155 2 jet sizes up? 152.5?

 

[[email protected]]

Am i misreading or is 150 to 155 2 jet sizes up? 152.5?

What Eric wrote makes perfect sense to me

Sent from my SM-G900V using Tapatalk

 

[Traumahawk]

Geesh, man...can't you be any more accurate?

:biglaugh:

Mark

LOL. well I try Mark.

What Eric wrote makes perfect sense to me

Sent from my SM-G900V using Tapatalk

Thanks.

 

[hypermax]

There are actually many Mikuni main jet sizes available to really fine tune if you want.

JET,MAIN #150
3G2-14231-30-A0

JET, MAIN #151.3
3G2-1423E-60-00

JET,MAIN #152.5
3G2-1423A-81-00

JET, MAIN #153.8
3G2-1423E-61-00

JET, MAIN #155
3G2-14231-31-00

 

[blaxmax]

There are actually many Mikuni main jet sizes available to really fine tune if you want.

JET,MAIN #150
3G2-14231-30-A0

JET, MAIN #151.3
3G2-1423E-60-00

JET,MAIN #152.5
3G2-1423A-81-00

JET, MAIN #153.8
3G2-1423E-61-00

JET, MAIN #155
3G2-14231-31-00

OK 4 jet sizes up then. Not 1.

 

[sdt354]

There are actually many Mikuni main jet sizes available to really fine tune if you want.

JET,MAIN #150
3G2-14231-30-A0

JET, MAIN #151.3
3G2-1423E-60-00

JET,MAIN #152.5
3G2-1423A-81-00

JET, MAIN #153.8
3G2-1423E-61-00

JET, MAIN #155
3G2-14231-31-00

And, with the Dyna jet sizes , there are plenty in between. Looks like that got covered.

 

[bumper]

Thanks, looking on the net I found this on a r1 forum,
As A guide, this is what I saw near my optimum tune point.


1 notch rise in needle ( e.g. 4 to 3 from bot) at 1/2 throttle will lower AFR 1 full point (e.g. 14.0 to 13.0).
A drop in Main by 2 sizes (e.g. 140 to 135) at 1/2 throttle will raise AFR 1 full point.(e.g. 13.5 to 14.5)
A drop in Main by 2 sizes (e.g. 140 to 135) at WOT ------- will raise AFR 1/2 a point.(e.g. 11.0 to 11.5)

SUMMARY: @ 1/2 Throttle: 1 needle notch = 2 jet sizes

So as traumahawk posted the wot follows and confirms the above info