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Discussion Starter #1
Ive got it about 12.8:1 right now, NA.....

Should i shoot for 12.5:1 on the spray? Mostly going to be quarter mile stuff. 91 octane, stock timing, my bolt on 12R, starting with a 20 shot then will work up to a 30 shot or even 40 shot.
 

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make sure u raise your fuel pressure when the nitrous kicks in. sry im no help when it comes to a/f ratio i never really checked mine on my old bike. your really just going to have to play with it. i would richen it up until its too rich then lean it out just a bit and u should be fine. start with 11.5:1 and see how it runs, your not putting too much spray through it so i wouldnt be worried about hurting anything on it.
 

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11.8 on spray. start off with a really small shot. stock zx12r fuel system is pretty weak. i already have my stock pump and injectors maxed out on motor. if you are running a small shot and have a stock motor, you might be able to get away with keeping duty cycle at or under 80%. if not it is time for bigger injectors, or more fuel pressure.

as a bare minimum, upgrade your fuel pump before trying anything! walbro gss242 is the one to use
 

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Discussion Starter #5
11.8 on spray. start off with a really small shot. stock zx12r fuel system is pretty weak. i already have my stock pump and injectors maxed out on motor. if you are running a small shot and have a stock motor, you might be able to get away with keeping duty cycle at or under 80%. if not it is time for bigger injectors, or more fuel pressure.

as a bare minimum, upgrade your fuel pump before trying anything! walbro gss242 is the one to use
Ya I've been reading about the fuel pump. I'll be getting a new one ASAP.

I'm starting with a 20 shot, but bought the jets for 30 and 40. For sure won't go 40 without doing the pump first.
 

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see sig, dads 2000. 1287cc i did the head, stock cams, stock pump. stock injectors, stock fuel pressure, dry shot, brock sw, pc3r

on a 20 shot 12.8 would be fine (go richer as you go bigger). thats going to put you on par hp wise with a streetable 1375 right?
 

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see sig, dads 2000. 1287cc i did the head, stock cams, stock pump. stock injectors, stock fuel pressure, dry shot, brock sw, pc3r

on a 20 shot 12.8 would be fine (go richer as you go bigger). thats going to put you on par hp wise with a streetable 1375 right?
Cool, thanks...

with a 20 shot, should be right around 200-205rwhp, and with the 2.5lb bottle it should last a while so I'll be able to get a descent amount of runs in before a refill. should be fun for a street bike. I bought jets for 30 and 40hp, but probably won't use them until I do some other mods first. on par with a streetable 1375? LOL, i have no idea what they put out HP wise???
 

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yeah with that small of a shot your current a/f is just fine, heck on my 150 shot im at a perfect 12:1 for over 2 seasons now, runs its butt off with absolutely now issues. this is not on my 12 though, its on my busa (dont ban me yet, i love my 12er too)
 

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that's a little rich in my opinion, running a 50 shot, target a/f is a little over 13:1, getting down towards low 12:1 you're talking about losing power
 
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