Re: Carb problem in Gixxer

Thread approved.

Re: Carb problem in Gixxer

Have you reverted idle speed settings from 3.5k?

Re: Carb problem in Gixxer

There's no need to tune the carb of a vehicle unless its been fiddled with, or you are modifying the vehicle for more power or different environment and terrain.

The screw you've turned may be something else entirely, or its quite possible that you didn't warm up enough, or your carb model supports only limited range of AFR change..
Another possibility is that your odometer may lack in accuracy, specially because its digital, so its not registering minor changes in rpm. If so, you might need to "hear" the rpm change from the engine sound...

For now, you must ride around in the city for an extended duration, preferably in the daytime and then check if the idle rpm is fluctuating.

Air-fuel ratio (AFR), if it becomes lean, it means more oxygen and lesser fuel, thus causing overheating and lesser rpm stability.

Alternatively, if all else fails, you can get your exhaust checked with a CO2 machine, and that will help determine the best AFR for your environment.
Thereafter, avoid tampering with it unless there's a strong reason to do so.


NOTE: Fuel mileage may vary due to a lot of reasons. You must be in a gear which has sufficient torque, and not necessarily in the top most gear. Sudden throttle must be avoided. Riding habits make a difference too.

Re: Carb problem in Gixxer


I don't mean to question your knowledge, just providing my guesses, I could be entirely wrong and as a result could learn something new myself.

Maybe his AFR screw was already at a leaner settings (like 2 full rotations anti-clockwise only) before he set the idle at 3500 rpm? It could be done by the service center by mistake or by him out of negligence.
There is also possibility of choke cable being stuck and not fully disengaged, that would explain idle rpm not dropping and also bad mileage?

Re: Carb problem in Gixxer

I too guess a stuck choke or something similar. I've read similar things in Gixxer forums – high rpm due to some stuck rubber part.

Re: Carb problem in Gixxer

Nope, the afr screw was @ correct setting (2 turns out 2*360 degree, from the leanest point)! If it was already lean, then I would have faced power loss which is not the case.
The problem is that, the rpm if set @ around 3k or below and on turning the afr screw to its leanest position, the bike should shut off as there won't be any fuel supply; which I also examined on my friend's Gixxer. But, with my bike it's just not happening.

I also checked with the choke cable it's fine.

Re: Carb problem in Gixxer

It seems you have gone to great lengths to solve this problem. Don't you think the problem has to be because of carb cleaning done improperly by the service center? From what I reckon, even after setting AFR to zero position, fuel is STILL getting into the mix inside the carb, that's the only reason idle is not dropping.

I would guess that the ASC guys messed up either the pilots or diaphragm. These two are the highest probable reasons. First try a simple thing yourself, tighten the manifold rings on both ends of the carburetor, tighten the screws as hard as you can, there is no need to be gentle because loose manifolds cause vacuum leaks and that could be a reason for rpm's not dropping.

I also googled your problem and found this page with some good info:

Mixture screw has no effect on RPM (pilot too big?) [Archive] - The Sportster and Buell Motorcycle Forum - The XLFORUM®

Re: Carb problem in Gixxer

Clean carburettor and fit new fuel screw. During previous cleaning SVC may have lost or damaged the o ring in fuel screw. Changing the screw with new kit will solve it

Re: Carb problem in Gixxer

Yes I think the same, the svc guys would have messed it up.
Thanks for the inputs, I'm taking it to a well known local mechanic tomorrow and would check with the same.

Re: Carb problem in Gixxer

Thanks for the input. And is the fuel screw available separately at the svcs?

Re: Carb problem in Gixxer

Yes. What is the model of carb.i can tell you alternative.

Re: Carb problem in Gixxer

I don't know the model of the carburettor, couldn't even find it online

Re: Carb problem in Gixxer

Check on manual
You can upload the carb photos from different angle.

Re: Carb problem in Gixxer

Here's the video reference of the carb: