Slingshot carb help

[Spyder]

I have a 1995 GSXR 750 W. Stock engine, stock header with a pipe and D&D, stock airbox with a K&N. Previous owner REALLY did a bad job tuning the carbs. I believe they are 36mm. Stock jet was a 115 (seems small) I have had them apart and fully cleaned them. I have screwed around with the jetting a couple times with no change. Come to find I have a weak spark problem. Once I get that fixed, I am looking for the best starting point with jetting and needles. Hoping not to have to pull them out again after this last time. Anyone with experience with these please chime in with any advice. Thanks...

 

[TxGSrider]

I would think you'd want about a 130 main.

 

[Spyder]

I was thinking the same thing. That's what I bumped it up to. And the needles to the middle slot. After it still fell on it's face, I lowered them one notch... Will test there, but thinking I will need to raise again... Once I have strong spark again...

 

[TxGSrider]

One of the problems with those carbs (I have a set on my GS1100) is they are notorious for wearing out the emulsion tubes and being impossible to tune in that condition. I'd look around for a Dynojet kit (even if its a stage 1 and not stage 3) and use their needles and emulsion tubes (their emulsion tubes can usually only be used with their needles as they are larger in diameter).

 

[Spyder]

I did a crude inspection with a digital caliper and they are good. Look to be replaced at some point...

The last guy to go through these carbs was wearing make-up, and long red shoes. Stock jets, needle adjusted ALL the way up. Pilot screws turned out (in order 1-4) 4, 2.5, 1.5, 3

And you won't believe it, but the bike ran GOOD. Fast ! So much "engineering" on this bike it's sickening...

 

[trippivot]

if you think the mixture screws have to be the exact same turns out from seated you will never tune to a decent level.

rarely do you ride on the main jet. change them LAST - and only in 10% increments when you are searching.

#1 = increase the pilot jet 1 size - needle groove 1 under center for the Midwest . then lean idle drop tune your mixture screws.

 

[Spyder]

Turns out I have major wiring issues. I separated all the plugs in my harness, and cleaned, and greased them. All back together, and now I have a no crank issue. UGH... I ordered some new plug pigtail setups. Going to replace all the main plugs... THEN, I can see where my carbs are...

Thanks for the replies. I know the process of tuning the carbs, was just looking for a solid starting point for my setup to minimize how many times I have to pull them...

 

[posplayr]

http://www.factorypro.com/tech/carbtun.html

 

[TxGSrider]

http://www.factorypro.com/tech/carbtun.html

That link helped me so much when I was setting mine up.

 

[posplayr]

That link helped me so much when I was setting mine up.

Yes, I think it is the best general reference on tuning CVs. Starting on the main and working down, is perhaps not the only way to tune, but it certainly seems to be the most efficient. Once you set the main, there is no way that the smaller stuff would necessitate a further change in the main. On the other way around is not true.

That said, when I was using my WB02 sensor, I was monitoring the AFR changes as a function of independent jet and needle adjustments. So after a while was able to make two changes at once (main and needle) and improve the AFR results as I wanted.

 

[Spyder]

VERY helpful link, thank you very much. I printed up both High, and Low RPM write-ups...

 

[Guest]

Factory pro kit on my '89 short stroke 750 motor. Tried Dyno jet kits in the past, pure poo....