Carb Video

[BEESY]

Just come across this video on You tube. Some pretty incredible footage of what goes on inside your carb.

https://youtu.be/toVfvRhWbj8

[royblackburn1@btinternet.]

Hi BEESY enjoyed the video can understand how important it is to get the valve timing right to get the carb working efficiently, Roy

[DAVE BRADY]

Hi,

Just watched the video and it is very informative.  That was just the main jet so I am looking forward to the video including the  the pilot and needle jets.
I noticed that once the engine was running, the fuel came up in to the venturi as a squirt of liquid when the valve was closed and the rest of the cycle was taking place.  This was obviously needed for the next intake so that there was no delay in fuel having to be sucked up through the jet again.  So did the turbulence in the float chamber caused by the vibration of the engine cause some petrol vapour to form above the liquid.  This vapour would want to expand but the confines of the float chamber would cause an increase in pressure above the liquid.  This pressure would then push the fuel through the jet so acting as a weak and uncontrolled injector.
Possibly, probably or total rubbish?

Dave.

[Pete Gill]

Yes is good to see.
It reminds me that fuel/air mix into the engine is mainly governed by the speed of the engine and vacuum effect of the intake stroke.
Sometimes we can lug the engine too much at low speeds in top gear, it doesn’t really do it any good merely opening the throttle to go faster -  we need the engine speed to suck the mix in!
Pete

[DAVE BRADY]

Hi,

I suppose this is why a long stroke engine is more luggable as the higher piston speed will create more suction at lower revs especially with a relatively small choke/carb size.  However, having a few more revs not only benefits the engine through the carburation and better oil circulation but also smooths the primary transmission and keeps the gear box spinning.

Dave. 

[idie]

A very interesting video. You can see why car carburettors had twin chokes especially those with two different size venturis. A small one for fast air flow for normal running and a large one for running at speed. 

[DAVE BRADY]

Hi,

I think there was a competition MZ that had two carbs. and perhaps other 2 strokes.

Dave.