Carburetor Thread

[psr]

I was trying to tune the carb & during that process, I'd tightened the airscrew to max. Then all of a sudden the vehicle started revving at high RPM

Is it ? But PSR ji, it happened only by playing with IDLE screw not with air screw. I tightened it to the extreme & once released, things became normal. Color of plug was tard black.

Which of your post is correct ? I made my observation based on your earlier post....#82
If your later post is true,then the reasons for increased RPM even with throttle closed are:
1. Your throttle slide got stuck .
2. your throttle cable is not free and should be lubricated.

[aargee]

It is called pre-ignition...heat range being hot.

Is it ? But PSR ji, it happened only by playing with IDLE screw not with air screw. I tightened it to the extreme & once released, things became normal. Color of plug was tard black.

[psr]

This weekend I'd a very weird situation. I was trying to tune the carb & during that process, I'd tightened the airscrew to max. Then all of a sudden the vehicle started revving at high RPM & when I switched off the keys, nothing stopped, it still kept revving at high RPM & the carb was doing its job beautifully.

What happened here? I assumed that, the suction pulled the AF mixture from the carb indefinetly. But on turning off the key, the CDI should've stopped doing its job, but it didn't. What am I missing here?

Any thoughts on this is highly appreciated.

It is called pre-ignition and happens when the AFR is lean and the engine is hot,and if the compression is way higher than normal.You should check your Spark plug's heat range also. A stock engine will never face this problem...you may post the alterations if any,you have done which might give a clue and possible solution....but judging by your say, it seems to be lean AFR(air screw tightened fully) and or ,plug heat range being hot.

[aargee]

This weekend I'd a very weird situation. I was trying to tune the carb & during that process, I'd tightened the airscrew to max. Then all of a sudden the vehicle started revving at high RPM & when I switched off the keys, nothing stopped, it still kept revving at high RPM & the carb was doing its job beautifully.

What happened here? I assumed that, the suction pulled the AF mixture from the carb indefinetly. But on turning off the key, the CDI should've stopped doing its job, but it didn't. What am I missing here?

Any thoughts on this is highly appreciated.

[aargee]

^^ Ok ji, will look into it this evening. Tks for your help.

[psr]

I'm aware of Pacco India!!! I was asking how does the

looks like

It looks like any other screw,but is situated close to the drain tube.

[aargee]

two wheeler carburetors manufacturer, two wheeler carburettors exporter

I'm aware of Pacco India!!! I was asking how does the

bleed screw for bleeding out the bowl petrol along with dust accumulated in bowl

looks like

[psr]

Saar, pics pls? Any other possibilities like float etc?

two wheeler carburetors manufacturer, two wheeler carburettors exporter

[psr]

Saar, pics pls? Any other possibilities like float etc?

With the carburetor image shown ,if the float gets stuck Petrol will flow out of the mouth of carburetor..

[aargee]

There is a bleed screw for bleeding out the bowl petrol along with dust accumulated in bowl.

Saar, pics pls? Any other possibilities like float etc?

[psr]

What are the possibel reasons when the fuel flows out of the carb? Especially from the transparent tube underneath the carbs

There is a bleed screw for bleeding out the bowl petrol along with dust accumulated in bowl. If this screw is not tight or not fitting properly then petrol will seep out through the transparent tube underneath the bowl.

[aargee]

What are the possibel reasons when the fuel flows out of the carb? Especially from the transparent tube underneath the carbs (as shown in the pic below)?

[dafc]

I am heading North for Health

hahahahaha lol

[psr]

PS - This is not all, I'll come up with more questions as I keep chewing these thoughts

Come up with more
I am heading North for Health

[psr]

Thanks for the appreciation.

As an end-note, I'll give you an analogy that you'll probably remember for long. Its to do with 'pumping efficiency' and its something you survive on. The human heart. Thats a pump whose output keeps you alive. The heart's pumping efficiency lies within a certain 'pulse' range - somewhere between 50 BPM (beats per munite) to 160 BPM depending upon your age. Below 50 BPM the suction and pumping strokes are not strong enough to push blood through to the farthest reaches of the body. Above 160 BPM, the suction and pumping happens so quickly that the heart can just pump a very small amount of blood during that short time. So a black-out through lack of blood to the brain lies at either end.

It is the same with all pumps and the engine is one too. Air has inertia just like blood. And so needs time to start moving. If the suction stroke ends even before the air has reached the peak velocity of travel through the venturi, then the engine will starve for air. Which is what happens with narrow venturis at high RPM's.

And it is precisely this 'pumping efficiency' that makes peak torque available at max intake manifold vacuum.

Thanks OLD FOX, for bringing in another two stroke pump into focus,and the simile is most appropriate.....a true FOXian explanation.