Villiers carb

[adi]

The carb on this engine is villiers own brand slide throttle, and i cant figure it out.

Iv tried searching for info, and i found stuff about the usual villiers cabrs, but this one isnt like it.

This is the stock carb for the Mk I scootacar as far as i know. I would get a picture of it, but 1) its hard to get a clear photo with my camera and 2) im sure you guys know exactly what it is anyway.

So, unlike the carb i found info on, my carb has:

-No external needle adjustment. No fitting for a rich/lean control, at all. The needle appears to be pre-set by a screw which can only be operated with the top of the carb removed! The info i found on carbs says that it should either have a cable fitting for a remote lever, or have a lever sticking out of the carb.

-A screw in the side just past the venturi, im not sure wether this is a mixture screw, a idle mixture screw, or maybe a air bypass screw for setting idle (but im not sure...it looks a little small for that).

So, hers some info im after,

How is the needle adjusted? does the screw that holds the needle in have some kind of preset setting? Because i cant see how its possible to adjust it with the engine running...since the top of the carb needs to be removed. What do i do with this screw? Iv alredy disturbed its setting so i cant just leave it alone.

Whats the spring loaded mixture screw looking thing sticking out of the carb for?

How do i control idle speed??? I cant seem to find any adjustment for this, and its a little low at the moment.

And finally, i left the fuel on by accident and came there in the morning to find the contents of the fuel tank in the crank case! So i assume either the float valve is punctured, or the float is somehow sticking open.

How does the float valve arrangement work on these?

If someone could throw me some info about these things would be much appreciated.

Thanks

[marcus]

I know just about nothing about carbs or Scootercars, but there might be a fuel tap which you have to turn off when you are not using the car, many of the old micros have them, once on the road, you will at some find your engine dies because you forgot to turn it on again !

[Jawmedead]

Adi,
The Villiers S25 carburetter. A simple little device fitted to many 197cc Villiers engines. It has only one external adjustment, the Pilot-jet Screw.
The brass needle in the slide has a small spring fitted for tension when you adjust the screw that you found in slide. With the slide and needle out of the carb, the measurement from bottom of slide to point of needle should be 1.95" (just under 2") Turn screw to adjust, down to weaken, up to enrich. The screw on the outside is the Pilot-jet screw to adjust tickover speed. A good starting measurement point after dismantling is to fully turn in this screw and then unwind 1:1/4 turns but be ready with screwdriver in case it revs too much or not enough!!      The flooding: The fuel needle under the toggle lever inside the bowl could be sticking with filth after many years and won't turn off the flow of fuel when the float touches it. I expect the carb could do with a good clean, preferably with an Ultra-sonic cleaner.

This should be the type of carb as yours, air filter fitted on left side.

It also may have two cables, throttle & choke.

This may sound daft but don't forget the Villiers 9E is a two-stroke needing a petrol/oil mix in the tank.

Unfortunately I have just recently sold a Villiers manual & spares list on eBay for 99p or you could have had them.


Rob.D. 

[adi]

OOOOH....ok...that makes things a little clearer. Thanks for the info.

So the thing in the side is the idle speed adjuster? thats cool.

So am i right in assuming that it works like this:

The throttle stays FULLY closed at idle, but has a small recess in it which allows some air to go through even with a closed throttle. This air goes past the auxiliary jet, which is controlled by this screw, so in effect the idle speed is controlled by mixture, not by throttling?

About the needle, so i need to adjust the screw appropriatly for the needle to be about 49.5mm tall when measured compared to the base of the throttle slider?

One problem.

I found that in my carb, for whatever reason (probably general wear and sloppyness?), its impossible to insert the slide back into the carb with the needle in situ. I guess the needle must be a tiny bit bent or uneven or something, but either way, if you try that the needle ends up hitting against something and not quiet going in the jet.

So the only way is to take the needle out, insert the slider all the way down (so the needle hole and the jet are next to each other and line up) and then put the needle in, then lift the slider appropriatly and put the screw in. If course thats bad because then you cant measure the height of the needle.

I COULD set the needle to the right height and count the turns of the screw, and then assemble it and turn the screw that amount of times, but thats not that accurate.

[Jawmedead]

It's easier to fit the slide/needle with the carb off the engine unless you can guide the needle through the airfilter side with a finger. Saying that, it's easy on a motorcycle but impossible with your backside up in the air in a Scootacar.