mike prior Posted January 17, 2011 Share Posted January 17, 2011 Can anyone please help with the setting of the TN (twin needle) carb on my enya 50cx? I want to set the gap adjustment between the 2 needles. The manual is a little hard to understand as it says 'Just 100% the low idle screw'. Now are they saying fully screw clockwise or anti-clockwise? Fully clockwise sets the carb to fairly high idle & anti-clockwise closes the barrel completely for no idle. The rest is of the set up is easily understood Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted January 18, 2011 Share Posted January 18, 2011 Mike, I'm not familiar with Enya carbs but I think they are pretty similar to most other twin needle carbs on other engines....if so then the following method should work OK. Just to clarify too its not the "gap" between the needles that you need to set as such......a quick explanation as to how these carbs work might help..... At full throttle the carb barrel is fully open & air flows into the engine pulling in liquid fuel via the main needle. This needle is tapered & controls the fuel flow so screwing the needle in lessens the amount of liquid fuel supplied & weakens the mixture.....unscrewing it allows more fuel though & richens the mixture....so far, so straightforward!!! Now as we close the throttle it is guided by a helically cut slot so as the throttle barrel rotates it moves to the side. The side where the "idle needle" lives. So as the throttle is closed the tapered idle needle starts to limit how much fuel can flow & when the throttle is at idle the mixture is controlled by this needle. As before the further in it is screwed in the less fuel flows & the weaker the mix..... OK so how to set it up in the first place......fit a piece of fuel tube over the fuel inlet nipple & open the main needle about 2 turns (not critical). At full throttle you should be able to blow through the fuel tube & hear a hiss as air flows through the needle valve. Now, take a modelling pin & use it to stop the throttle barrel from fully closing (so the barrel is open a pins width yes?) lightly screw home the idle needle until it seats. At this point you shouldn't be able to blow through the fuel tube. Then slowly unscrew the idle needle until you can just blow through the fuel tube.....thats it......remove the pin & fuel tube & start the engine......the idle needle might need a slight tweak either way but it should be very close. Incidentally the throttle stop screw (usually on top of the carb) should be set to allow the throttle barrel to close completely......this allows you to stop the engine via the throttle servo......the idle speed is set by the servo position. Hope this helps...... Quote Link to comment Share on other sites More sharing options...
mike prior Posted January 23, 2011 Author Share Posted January 23, 2011 thanks Steve, very helpfull regards Mike Quote Link to comment Share on other sites More sharing options...
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