With a Carburetor a Roll Over sensor is not required.....
If bike is still able to do 120~130, what exactly is your problem ? can you be more precise ?

Expected this question .. Sorry for creating ambiguity here.
The problem is bike shutting off abruptly as if there is no fuel. Since my bike does 120~130 lets presume the carb conversion job is done alright. Assuming that, what could be problem with carburater for leading to bike shutting off abruptly sometimes ?
My suspicion is bad tuning state of carburater .. Haven't really got it tuned after the set up change. Asking help to iron out the occasional abrupt shut down of engine.

Again there are presumptions....
Assuming your carb., conversion is correct, and bike does 120~130 ,then I don't suspect carb tuning.It is either the Electronic rev limiter , or vapour lock...when the bike struggles at high speed, try opening the Petrol Tank cap..with the spare key.If this solves the problem, you have vapour lock...
There is a filter in the petrol tap both inside the tank and at the bottom of tap...if any of this is clogged then the problem you have reported can happen.

Thanks PSR ... The solution looks reasonable cause welding work was done on the tank (FI tank is different than DTSI tank, did not go for new tank for obvious rea$on$) .. Will update on this once I get the tank cleaned and required filters put in order.
And just realized .. there is no filter on the fuel line .. holy crap..

Since this thread serves for general discussion on carbs, I had a few questions and hope if the experts shed some light on the same.

1) I have read in many articles on the internet that for coasting in a car, it is better to release the accelerator and let the car coast and decelerate slowly (combination of low engine braking in highest gear + air resistance) rather than leave the accelerator and engage clutch to decelerate (braking due only to air resistance). In the first instance the ECU of the car detects that accelerator is released fully and lets the engine run without any fuel thus the engine acts just as an air pump being run by momentum of the car. In the second instance, since the car has to idle, fuel is injected by ECU as required for idle. Thus hypermilers suggest coasting on a road without pressing the clutch. This makes sense for most modern cars which have fuel injection.

What about our carburetted bikes? I read that closing the bike's throttle fully also results in the same behaviour where no fuel enters the engine and it just acts as an air pump running on the bike's momentum and in turn slowing down the bike by low engine braking in high gear. However I am not sure whether this is true or not. Because, firstly wont incoming air suck in fuel based on venturi principle? And what about the pinging we get in exhaust on closing the throttle? Does that show that both fuel and air are being pumped through the engine?

Finally my question is this: For the purpose of saving fuel and getting max. mileage, is it better to clutch in fully and coast or close the throttle fully and coast? Also what are the pros and cons of both methods?

Thanks a lot, will really appreciate in-depth detailed explanation and sensible and convincing answers.

I think, when coasting in gear, with throttle rolled of and w/o pressing (disengaged) clutch, carb doesn't cut off fuel supply, completely. At least idle worth of fuel goes in. Talking about max mileage, without considering safety, riding pleasure etc. While coasting Turning the ignition off in a carbed bike will save you some fuel. Also in most Indian Fi cars, fuel cut off only happens above 2-2.5k rpm. Awaiting Experts Reply..

In a Fi engine with ECU control or engine with carburetor, the idle circuit continues to work as long as the engine is" ON ".If you de clutch or move transmission to neutral while trying to coast,the idle circuit will still be running the engine,and the resistance offered is only from the environment. If the engine is coasting with accelerator at rest,but in gear, the friction of the gear box,clutch,and engine will decelerate the vehicle faster than when coasting with gear in neutral.
Hence for hyper-mile it is better to shift gear to neutral during coasting...
With the engine and gear box dis-engaged ,braking distance will be more and caution is required.

@Honda_CBF and @psr Thanks for the reply. I conclude that clutching in and letting the bike slowdown due simply to air resistance + friction is better than adding in engine braking to the mix as well since in all cases the idle circuit will always be on and that amount of fuel will anyway be burnt.

true. (I do it, along with killing the ignition, only when I'm going to park my bike) But frequent use of clutch will wear it out sooner (if you are rev matching then also you are burning more fuel) also, increase in mileage won't be very noticeable if ridden within city. plus without engine braking, its always hard to negotiate out of tricky places and can also reduce your stopping power dramatically. So, doing it when on traffic isn't recommended.

Re: Carburetor Jetting and tuning for the correct AFR.

@psr Sir, has this graph which shows the level of various exhaust gases for different AFRs, taken into account the catalytic convertors present in the exhaust systems? I mean the graph reading has been done at which point? At the point where exhaust gases leaves the exhaust valve or at the point where exhaust gases leaves the silencer. Also if later is the case then the graph reading would change with the addition/subtraction of catalytic convertors in the exhaust system.

Please clear my doubt.

Re: Carburetor Jetting and tuning for the correct AFR.

Obviously before Catcon, since the catcon's condition can change over time and will make the tuning meaningless..Catcon helps to further reduce the exhaust gases toxicity , thus providing a better environment.

Re: Carburetor Jetting and tuning for the correct AFR.

Could anyone point me to someone in Hyderabad who can increase the size of the main jet by drilling it accurately please?

Re: Carburetor Jetting and tuning for the correct AFR.

It can never be done accurately...better to buy the jet size as required..

Re: Carburetor Jetting and tuning for the correct AFR.

Sir clear one doubt. When tuning a CV carb or any other carb, we turn out the fuel screw out anti-clockwise from it's bottom end position until the peak RPM is reached after which the RPM decreases again. So why we look out for that pick rpm and stop there and how does that translate to this number of turns as being the correct number from bottom end position?
And sir is this fuel screw decide the A/F ratio only for the pilot circuit or till WOT?

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Re: Carburetor Jetting and tuning for the correct AFR.

If the carburetor has a FUEL adjustment screw ie., adjusting the Amount of fuel then turning Clockwise make the AFR LEAN and Vice verse. If the AFR screw is an AIR Adjustment screw then turning it clockwise will make AFR RICH. The AFR adjustment is for fueling from start to approximately 1/3 of max RPM .
Here is a representative image to explain things in correct perspective.