villiers air filters.

[James8672]

Just a quick question...I have two types of air filter for my S25 carburettor. One is a small type with a built in choke, and the other is much larger and with no choke. On this one the casing splits in half to access the element. Why are they different? .
Is one better than the other?.
I'm currently using the smaller air filter with built in choke and I'm having no issues what so ever.
I'm looking to sell one but dont know which one to keep and why.
Any ideas?.
Cheers,

James.

[John Wakefield]

The smaller air filter with choke was originally fitted to the earlier 8E type engine & carried forward to the 9E, but later replaced with the larger one.
From pics, Greeves fitted the larger one back in 1958 so I think its fair to say that they did not fit the smaller one. The carb on the old 8E did not have a choke built in so one was needed in the filter. The S25 was available with built in choke. I would keep the larger one as that would be correct for your bike.

[James8672]

Thanks john.

Would the lack of choke be much of an issue if I fitted the bigger filter?.

[John Wakefield]

No as long as you have a choke slide in the carb.

[mayfield]

villiers air filters

I suggest that you try both,each engine seems to differ,I have two villiers twins one needs choke the other not.in brief if no choke in the carb.one is normally required on the filter.I hope this helps.

[James8672]

Mmmm...tricky choice. The bike runs and starts perfectly with the small air filter/choke type fitted so I may stick with that set up and save myself any frustration.
I have a photo copied book on villiers carbs but it doesnt show a choke In any of the diagrams - the print quality isn't great though so I may be overlooking it.
Would it be the same idea as on the amal?.

[John Wakefield]

Yes basically same set up as the Amal, a slide which is either lowered by plunger on top of carb or by cable from a lever on handlebar.
As regards the filter, both types are wire gauze so do the same job, I would say the is no advantage to the running of the engine, just really whether you a re 'rivet counter' & want the bike to look how it was built.

[Brian Thompson]

Villiers Carbs/Filters/Choke Slide etc.

There's a bit more info and some pics here that may help with this one, although sadly I didn't get any response when I originally posted my query back in 2010....

If using the larger filter and without a choke, just flood it well with the tickler.

http://www.greeves-riders.org.uk/forums/showthread.php?t=2237&highlight=villiers+carbs+originality

Brian.

[John Wakefield]

A good insite to the air filter query Brian, As for the 'bored out to 1" S25" I never got any real answer to this when I posted the qustion on here. As I see it the standard S25 had a bore of 25mm, & 1" is 25.4mm so only .4mm larger choke which would not give any appreciative increase in performance. Like you Brian I got very little positive feed back. Maybe someone can accurately measure a S25/1 to see what the bore size actually is.

[greeves246]

1800

the bigger filter was always know as 1800 filter (ususaly best as you can take them apart to service the element )

Thanks john.

Would the lack of choke be much of an issue if I fitted the bigger filter?.

[hawkie197]

S25 carburettor bore measurements

John, To answer your question about the size of Villiers S25 carburettors I recently fitted an idle screw to mine and also took the opportunity to bore it out to 25mm, the bore of the stub on the manifold is 1”, if it works well I might take it out that bit more.
After measuring up a few standard bodies (S25/_ , S25/1, S25/3 and S25/6) I came to the conclusion that 0.930 to 0.940 inches (just shy of 24mm) is about the norm, mind you they are diecast, not machined and not truly circular.
When I machined mine out it took a 0.010” cut to clean it up completely.
Cheers Pete from the Antipodes

[John Wakefield]

Thanks for that info Pete, strange that Villiers did make them a full Inch in the first place. Even so I dont expect 1.4mm extra in dia will make much difference.

[greeves246]

just to add

Hi
steve gollins has 1000,s of new 1900 filters and he makes the choke arrangement as well so if you want to put the original assembly on you could