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Carb help. Need advice

1137 Views 5 Replies 2 Participants Last post by  Monolith
Hello everyone. I really need some guidance with a situation I have going on. I have a 96 gsxr750 with a KN filter but I believe it’s the original box. I have a Yoshimura RS-3 exhaust I have cleaned the carbs before on the bike and put them back together with no issues other then not being perfect due to syncing might be off without the right tools. Carbs were 132 outside and I think 130 inside. So I bought a all balls racing carb jetting kit to get it back down to stock. So I replaced everything other the the carb bodies. The needles that were in there had notches and the new needles don’t. The jets are 127.5 factory and everything else it’s supposed to be. Air screw is two turns out.
so the problem I’m having is it’s running like crap. Blowing a crap ton of smoke. Really when you rev it. Idle runs like crap and if you go to give it throttle it bogs down orwill die. If it doesn’t die it will pop but mostly blows smoke.
So my question is... should I go back to the jets I had in there or stick with stock?
Should I replace the needles to ones that have notches to control them better. I’m at a total loss of what to do and I feel like I’m chasing my tail. I do have videos of it running if that would help someone understand how it sounds and what it is doing. Please help
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Guessing you likely had a carb rack with aftermarket needles and it was jetted to match. Impossible to know without seeing the needles.

Now that you’ve changed the jetting drastically, of course it’s not rite. And you’ve introduced manny variables of possibilities of what could be wrong. Without someone knowledgeable physically handling the carb rack, your rabbit hole of problem possibilities could be endless.

RS3 canister will make zero effect on your jetting because it is essentially the oem canister.... it’s a bolt on canister, you have a oem exhaust.

I’ve never seen the all-balls “jet kit” but I’m willing to bet the jets you bought are not OEM mikuni and it’s very likely their tolerances and sizes are not identical between their numbering scale. If you want it to be right, you should have replaced what you took off with the same brand and size as what was on there. Without seeing the stamping on the jets you used to have, it’s impossible for us to tell you if you had dynojet jets or oem jets and etc others before.

K&N air filters Are garbage on your carb’d srad. Throw it away. If you want a permanent cleanable/reusable air filter, buy a BMC “race” air filter online. Otherwise buy a oem air filter from a suzuki part vendor.

Also the srad carbs are not sensitive with syncing. Doing a bench sync is fully adequate if done correctly. Typically people mess up the 2.5 turns out from fill seated on the air fuel set screws, thinking they are tuning it, but in reality they’re just buggering it all up and repeatedly crushing that oring quickly making it a problem. Other thing people tend to bugger with is the float height setting, it’s 7mm from the highest point of the float to the surface... without the special tool for the job, it’s pretty easy to mess that up and have variable settings ranging around 1-3 mm in error from just not understanding it’s the highest point, not the highest point you can jimmy rig with a peice if paper or caliper tail end. And while on that mindset of area, aftermaket needles and needle seat buckets suck. Chances are high the more you fiddle with the carbs the more your going to need to replace from unintentional damaging. Essentially every time you see a oring or handle a peice with rubber on it, your likely going to need to replace it since our fuels all have ethanol in them, the rubber takes a beating. Mostly on the float needles and buckets. But you’ll know when they fail, you’ll have fuel all around your bike and engine.

Also did you forget to connect the Y pipe to the front of the airbox?

I should have made this response shorter.....
Throw away your k&n
Throw away whatever you got from all balls racing and put into your carbs.
If you want the carbs to be rite, buy oem mikuni parts either from suzuki parts themselves or mikuni themselves or authorized resellers.
Check your Tapered needles and see if they are adjustable, if so, you got kit needles, either way upload a photo of your tapered needle and we could help you identify them to get the correct jetting in the first shot.
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Thank you so much for all that Info. I starting to feel like this is something I should have never messed with. Now I’m going to be pulling them apart since I pulled the kit out- cause I keep all the old stuff. Discovered jets in. 4 125 and 4 127.5. So I guess for some dumb reason I left the 130 and 132 jets in the carbs but put the new needles in it. I was very careful with each carb so I have no idea why I would have done this. So now it sounds like I’m going to need to dig into them and figure this mess out. I do have two videos on how it’s running if someone will give me their number so I can send it to them since the forum will not allow videos.
If need be I don’t mind helping you sort it out.
Ok so I got the bike back together and I swear it’s one step forward two back. While I had everything torn apart I check all four plugs and they all are firing. Put them back in. Got rid of the new jet kit and put the bike back to the way it was. Interesting that cy 1&4 are 130 while 2&3 are 132. Anyway. Go the carbs back on the bike. Two turns out. Fired it and it sounded way better. Noticed the fuel line was dripping so I pulled it back off and fixed it Then when I went to start it I forgot to plug in the little solenoid that sits on the back of the carbs that’s hooked to the vtv valve or whatever. Not sure what all that does with those vacuum lines. When I went to start it fuel started shooting out the top of the carbs and pour out the line that connects to the air box in front of the carbs. It did all this once the fuel pump primed. Anyway I then pulled the plugs just in case fuel got into there and I didn’t want to cease the engine. Yup Gas shot out of the cylinders once the spark plugs where pulled.
Now what I don’t understand is why I’m getting fuel everywhere. Someone said my floats might be sticking but I just cleaned all that out. Could it have been that little valve not not being plugged it. Once it did it once I noticed it wasn’t plugged in and I did plug it back in but gas still poured out of that air box hose. I’m at a total loss
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Hit me up this weekend if your still having issues with it. I sent you a message awhile ago.

Having the solenoid not electrically connected should not cause that. Having the hose routing disconnected possibly could.

More likely is your floats needles or float bucket needle seats...

Did you remove the buckets and reinstall them? That oring is unique and does not like to be re-used. And the aftermarket seat / needle kits never seem to work properly. A problem at the float needle bucket can result in fuel shooting out the air jets upwards into the airbox.

If you’ve taken your carb rack off enough times you know it’s pretty quick to drain the fuel out the Y pipe by turning the carb rack upside down....similar interaction going on here....

If the float needles do not seat properly they’ll just dump fuel as fast as the pump provides it. A stuck float or float needle usually happens if the carb rack gets turned upside down before installing the rack. A light tap with a rubber mallet or soft piece of wood can dislodge a stuck needle.... but if the tip of the needle or the bucket itself (including o ring) is damaged or failed, tapping it wont help at all.

When you set float needle height, did you measure them with the float needle compressed? They should be measured uncompressed.

Shouldn’t the mixture screws be set to 2.5 turns out , not 2. And the inner jets are sightly larger because the inner two cylinders are slightly hotter than the outer edge two cylinders.
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