Needle Setting

[tas850g]

At first I just wanted to determine which was the 1st notch so I knew where I was starting from and which way to go according to specs. Who knows who and how many PO's have been inside e carbs. Therefore, I did jot expect it to be at stock settings.

Not to be a smart ass however, maybe I need to ask Mr. Yoshimura which notch is #1 because of the conflicting data.

This is for my GSXR.

Now, this leads me to the next question which I am experimenting with on my own. I dropped the needle clip down 1 notch to raise the needle and it ran worse. Still stumbling between 6-7k rpms but picked up a more mild stumble at 5k rpms.

So I raised the needle clip to the #2 or #5 notch depending on which source you are referring to and it ran better. Got rid of the 5k rpm stumble and less of a stumble between 6-7k rpms. I would hate to raise the clip to the top position to experiment with those results but I may do that this week if I get bored.

It has the stock pipe, air box but K & N filter, and jets. It's not too bad disassembiling and reassembling so i'll see what happens.

[AJ]

At first I just wanted to determine which was the 1st notch so I knew where I was starting from and which way to go according to specs. Who knows who and how many PO's have been inside e carbs. Therefore, I did jot expect it to be at stock settings.

Not to be a smart ass however, maybe I need to ask Mr. Yoshimura which notch is #1 because of the conflicting data.

This is for my GSXR.

Now, this leads me to the next question which I am experimenting with on my own. I dropped the needle clip down 1 notch to raise the needle and it ran worse. Still stumbling between 6-7k rpms but picked up a more mild stumble at 5k rpms.

So I raised the needle clip to the #2 or #5 notch depending on which source you are referring to and it ran better. Got rid of the 5k rpm stumble and less of a stumble between 6-7k rpms. I would hate to raise the clip to the top position to experiment with those results but I may do that this week if I get bored.

It has the stock pipe, air box but K & N filter, and jets. It's not too bad disassembiling and reassembling so i'll see what happens.

When you dropped the needle lower, the stumble got worse and started to happen at lower rpms (5K). When you raised the needle a notch from the starting mid position, it got better, but is still there. You are probably close. As you have seen, you're also getting faster at changing the needle clip setting. I'd recommend raising it one more notch and see what happens.

Unfortunately, if you're already good with the lower rpm ranges, all you can adjust after raising the needle again is either the main jet size (go bigger one size - step of 2.5) or a slimmer/more-tapered needle. Fiddling with the mixture screw won't help at all up in this range.

[tas850g]

AJ,

So you understand, I am lowering the needle therefore I should be getting less fuel making it lean. Am I understanding it correctly?

I have only one more notch before I reach the top of the needle. I should give it a try just to see. It almost seems to clear up once I get to 7500-8k rpms.

Thanks!

[Steel Toed Tank]

I'm just wondering, on my CV carbs, the throttle slide position can change drastically, changing from one jet to the next as the engine climbs through the RPMs while I keep the throttle at a steady 1/3rd.

How does the throttle handle position apply to throttle slide position throughout the different RPM ranges?


Tank

[AJ]

AJ,

So you understand, I am lowering the needle therefore I should be getting less fuel making it lean. Am I understanding it correctly?

I have only one more notch before I reach the top of the needle. I should give it a try just to see. It almost seems to clear up once I get to 7500-8k rpms.

Thanks!

Sorry, Tas, sounds like I misinterpreted your results. Let's refer to Steve's helpful diagram. The #1 top slot (blunt end) lowers the needle, making your mixture leaner. If you moved the clip to #2, you are one position leaner than the mid #3 setting, but not as lean as #1.

If I understand your statement correctly

I have only one more notch before I reach the top of the needle. I should give it a try just to see. It almost seems to clear up once I get to 7500-8k rpms.

your carburetion got better (smoother/more power through the band) when you lowered your need to the #2 position (Steve's diagram), and now you only have a small stumble at 7500-8000 and the stumble at lower RPM is gone. This change indicates that you were too rich in the middle (#3) position and dropping the needle to #2 to make it leaner made it run better.

Your original picture isn't clear enough for me to see if this is one of the needles with the rapid taper like Dynojet sells, but if it is and your pipes and airbox are stock, then being too rich in the mid position makes sense. Likewise, if you installed a larger main jet, being too rich makes sense, and lowering the needle to make it leaner should make it better. Go ahead and try the #1 clip position, if it gets worse, you went too lean.

Guess we should have asked what you were trying to do in the first place! E.g., Are you installing a Dynojet Stage 1 kit?