First Time Ninja Started, But Has Fueling Issues!

[Speedy3]

issue: Motorcycle starts with full choke. Needs idle adjuster turned quite a bit, but will sit at 1.5k after a couple minutes. SOMETIMES. Other times it will die. If I am able to get it to idle with no choke, it will hesitate under a sharp throttle. Now I understand the engine is not warm, but I imagine it's worth mentioning. There were also a couple of times (can't remember if choke is engaged or not) that the idle hung around 2/3k even after throttle was closed. Now, the cables are not pristine, but the throttle moves fully under its own tension and the throttle position closes fully.

Before starting it (for the first time since owning):

• cleaned carbs fully (main jets and pilot jets. FULL daylight through every single hole). Air mixture screws @ 2.5 turns each

• New gas, New tank, adjusted valves, cleaned air filter

So far, as diagnosis, I have sprayed WD40 on all boots during idle, zero sign of any boots leaking (I read this is typical of hanging idle). I checked the clean sure system by feeling the air hose on top of the airbox: service manual says to check for steady pulsating air: check. All the hoses in the vac system seem to be connected very well.

I have researched a ton, but just about everything I find is "been sitting" or "haven't ridden it since"... All of the fueling pieces should be spotless from my work! I am open to any thoughts, but have these directed questions:

1. needed the choke on is consistent with a lean mixture, which I imagine hesitating throttle is also. That said, this bike has a short exhaust with no baffle, and I don't believe it was jetted accordingly. Would closing the air mixture screws a bit help remedy this?

I guess that's it. The guy who had this motorcycle was no where clean or meticulous with service. But the motorcycle ran, at least, without cutting out, hesitating, or over hanging. I'm so close to finishing this bike up, and I'm getting so overwhelmed

[Speedy3]

Current exhaust: Attached

[Flying]

Bring the idle mixture screws out to richen the idle circuit. Shimming each needle with one or two 3mm (or #4 SAE) washers will also help.

[Speedy3]

I will definitely try this today. Is it advised to try one over the other? As would one be a more fundamental fix over a quick fix?

[Flying]

Originally Posted by Speedy3

I will definitely try this today. Is it advised to try one over the other? As would one be a more fundamental fix over a quick fix?

Give a shot at shimming the needles first, it has a significant effect on how much fuel is delivered in the transition from idle through when you open the throttle quite a bit. The idle mixture is a finer adjustment than shimming and I've only really needed to mess with it because of the winter/morning temperatures around my own area.

[Motofool]

First, check that all cables going to carbs and choke are lubricated and have some slack and that the idle adjuster is completely free to adjust the position of the butterfly valve.

Second, the diaphragms must go up and down freely (commanded by the vacuum created by the engine) when you open the throttle.
Sometimes the lateral slides are not smooth.

The needles must follow the movements of the diaphragms.
Easy to assemble those incorrectly, resulting in a loose linkage to the diaphragms (needles do not follow then).

[Speedy3]

Got her going!

Took the carbs off again to adjust the mixture screws! Took the time to recheck the jets... All superbly clean.

floats measured 17mm, everything seemed pristine...

I mentioned the last owner placed a WIDE OPEN shorty with no accompanying carb work done

So, while the carbs were off, I decided to do everything I could to get it close to how I want (even if it meant over enriching, just so I could see progress)

Well she started, with the choke (I had the idle adjuster completely not touching so I could get a feel of where it was at). I backed off the choke, and as it dropped below 1k, I bumped the idle adjuster up. I did this until the choke was completely off, and the idle was at 1500. After a bit, the idle climbed, closer to 2.2k, at which point I pulled back on the adjustment knob. Then she sat fat and happy at 1500. No hunting or anything. Furthermore, the throttle didn't hang a bit (so far as I can tell). The rpms didn't DIVE back to idle, but they didn't hang either. Here is the kicker: the mixture screws are backed out 4 TIMES! . I feel as that was the only way to make up for not having the proper jets.

Fuel air system is currently: snorkel > stock box and filter > stock jets > essentially a straight piped shorty.

I: added two washers for shims to each needle, adjusted mixture screws to 4 turns, and balanced the butterflies with feeler gauges.

I know the mixture screws may be out to much, so I'm going to let the bike cool over night, and see if I can start without choke. I read that is a symptom of too rich. If so, I'll back it off a bit!