Nibbi carb tuning

[kart74]

So I picked up a nibbi pwk26 for my mod 224. Previously had a mikuni 26 knockoff. Anyone have experience with these? I have it running good, but if you wack the throttle from low rpm (think hole shot) it just falls on its face. It almost shuts off. If I roll onto the throttle it seems good. Good power. Plug looks close. Never seen a carb do this.

 

[Minimichael]

Raise the needle, a clip or two. Look into a pilot jet kit. My guess is the carb is jetted too lean. And if you start looking at richer needles, look at Kiehin as I don't believe nibbi makes their own.

I had to richen the crap out of my nibby 24 and I believe it's because the throttle body is so wide and the slide distance so short that too much air is getting in all at once. Too much for cruising, anyway, more for racing?

 

[kart74]

I have tried the needle all the way the the lowest clip position and doesn't really change the issue. I started with a 35 pilot and have gone to a 45. It runs good but the quick opening is really bad. Yes mainly woods racing.

 

[Minimichael]

I have tried the needle all the way the the lowest clip position and doesn't really change the issue. I started with a 35 pilot and have gone to a 45. It runs good but the quick opening is really bad. Yes mainly woods racing.

Look into a needle with narrower body and shorter taper point (aka L1). You'll likely have to measure and match to what's out there. Like I said, check avail. Keihin sizes.

 

[kart74]

I will take a look. From past experiences it seemed that the needle change was more of a fine tuning thing. Do you think it would cause such a big issue? Cracking the throttle fast sounds like the kill button.

 

[Minimichael]

Certainly, I'm no expert, but I think you've got to richen up your early throttle position and every little bit can help. A narrower needle with an earlier taper helped me bridge the gap. Tho every situation is different as they say. What number main jet are you using?

 

[kart74]

I started with a 130 main and have also gone up to with that to a 145. Based on wot passes id say a 135 is where the main should be. I am thinking it may be too much carb.

 

[Minimichael]

I hear you. And not defending nibbi here. The one I have is definitely an all or nothing kinda carb. I'm very happy with it now and for that particular bike, tho I admit I won't be buying another too soon.