No...it is not the dimension you have indicated in red. In simple terms it is the vertical travel of the float. Hold the carb downwards (the way it is mounted in the bike) with the float bowl open. The float drops down and you can raise it up to a point beyond which it does not rise any further. The vertical distance between the bottom most point to its top most point of travel is what is supposed to be 21mm.

This figure need not be that exact (even the manual says plus/minus 1 mm) In fact too much travel and the carb will overflow. Too little and your engine will not cross a certain rpm. The position just needs to be approximately right. the adjustment by bending the tang is only possible on those copper floats.

Old fox Sir, first I'm delighted to see your post here.
Wonderful explanation there Sir on the working mechanism of the float. I wouldn't have suspected the float, needle valve assembly until at this stage. May be climbing down stage by stage here. First the color of the plug, AFR, leaks(flooding), float needle pin.

Prakash:- Do you have choke plug on the carb or at the handle bar? I would suspect needle valve assembly might be the culprit on which the float hangs.

Sriram - Yes,the choke plug is on the carb. Kindly advice how to go about checking " needle valve assembly".

Good news guys, I went to a mechanic(I had no tools) and had him adjust the carb as suggest and it seems to be working for now. I mean, I fueled up 1L on reserve and it run upto 27 and not gone to reserve yet .

Old Fox & Sriram - You guys are genius, your knowledge about 2 strokes is impeccable. Its been a week since I joined and two of the most irritating issues have been resolved.

THANKS GUYS

Did you try to know what exactly was the issue? And what adjustment was done to the carb? Post those details here so that if anyone in future faces similar issue would know what needs to be done.

Thank Old Fox Sir for the detailed explanation.

It was the float level that had to be adjusted.

Thanks a lot for all the help Old Fox and Sriram

Can that float level thing happen to other bikes too ?? I mean can having incorrect float level in mmy new bullet cause low average... kindly tell us about it please.. thanks

I believe float level is applicable for all the carb's and hence it will affect if its not set right. But you mention to have a new bullet and hence I don't think that is the reason.

@pv1984: Good to know things have worked out for you.

Good to catch you here Sriram.

I went straight to the float thing because in the very first post Prakash had stated that he'd had problems with a persistent fuel leak (which I suspect was actually an overflowing carb) and was solved by replacing the needle valve. A new needle solved the fuel overflow issue but the fuel level in the float bowl remained too high - hence the high fuel consumption. A stuck choke valve would usually cause the engine to what we used to call 'four-stroke' or 'Motorboat' as thats what it would sound like It is something you can replicate by stuffing the tool-kit of the Rx 100 into the air intake instead of its rightful slot right next to it as your's truly did many many moons and suns ago

And BTW, check out this link for some good details on carburettion if you haven't already that is.



Lovish: Yes...it applies to all carbs with float chambers. But do stress upon your mechanic not to make any big adjustment with float height or you could end up with an engine starved of fuel. Just a touch is needed. The usual 'ratio of adjustment to effect' is like 1:5 meaning that a 1mm adjustment at the float tang will translate into a 5mm change in the fuel level in the float chamber.