@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.

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.

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

It was the float level that had to be adjusted.

Thanks a lot for all the help Old Fox and Sriram

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.

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

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

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.

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.

So just so I understand clearly, the float level should be around 21mm. I have attached an image just to confirm if that is the float level...Kindly confirm

Should be more or less the same. I am not as familiar with the 135 set-up as with the '100.

As for replacing the carb, I don't think you need to go that far. The 135 carb can be set up properly to give you good economy too. I guess anywhere between 30-35 kmpl should be pretty good.

Thanks, You were able to find it

Btw, the carburater fixed is that of RS 135, so should it be the same(21mm) ??

Will replacing RX 135 carburetor to RX 100 affect my mileage or performance ?

I guess I was right with my hunch



That's a page from the RX 100 workshop manual.

Could someone confirm the value for float level?? I might get it tuned and check.

I also believe that the carburettor fitted is of RX 135 and not RX 100

Sriram - as Prakash says that he'd had the float pin changed, there could be an issue with the float level adjustment. If the fuel level in the float bowl is too high, it will result in a rich running engine irrespective of the idling AFR screw adjustment. Of course it will show with a dark brown or blackish plug. But the plug reading is valid only for an engine that's been run for an appreciable distance at normal or high speeds and has the 2T oil premixed in the correct ratio. Low speed high gear operation will show up as a dark plug.

If I remember correct, for the stock RX carb the fuel level in the float chamber should be 21mm above the chamber's lowest spot. An easy way of checking this in an appox manner would be to hold the fuel drain pipe upright next to the float chamber and unscrew the fuel drain screw at the bottom of the float bowl. Fuel will flow out into the pipe and rise till the level at which it is in the float bowl. Check if it is about 6-8mm below the float bowl edge. Any higher means that the level is high. I hope they still have those metal tangs on the float through which one can adjust the fuel level.