LCGB Forums

Ok I'm currently looking at different filter options, got everything running well without a filter but can't live with the oil slick ever increasing over the left foot board so decided to remove the baffle from the existing (S3) filter, cut off the neck and replace the neck tube with a piece of tube the same diameter as the hole in the top of the frame loop, this has given me significantly more performance than befor modification and also allowed me to go up 9 sizes in main jet.

Whilst experimenting yesterday I removed the scoop to see if that would improve things any but all that did was upset the carburation and killed everything right across the board.

So now I'm looking at different filter options and in perticular the breathe sweet with the large elbow to go over the 60 mm PHBH plastic bellmouth but at £40 seems a bit much, so what other options do I have? and what do you guys regard as good or bad etc.
Cheers in advance.

before you buy make sure that the breathesweet set up will fit under your panel.i ran one on a series 2 but it wont fit under gp panel.(this is 28mm delly .Rubber Mount).I guess there is more clearance on solid mount,so this may not be an issue depending on your setup.so as I prefer a filter for now I am stuck with the mb panel filter,and this will have to do until I find a combination of manifold and rubber that gives the clearance for the breathe sweet elbow.let us know if you find a solution.

bluebob wrote:before you buy make sure that the breathesweet set up will fit under your panel.i ran one on a series 2 but it wont fit under gp panel.(this is 28mm delly .Rubber Mount).I guess there is more clearance on solid mount,so this may not be an issue depending on your setup.so as I prefer a filter for now I am stuck with the mb panel filter,and this will have to do until I find a combination of manifold and rubber that gives the clearance for the breathe sweet elbow.let us know if you find a solution.

Thanks for your reply, yes it's a PHBH 28 on a special flange mount so everything lines up with the air box, looking under the panel there is very little room as that breathe sweet rubber looks massive compared to the standard one I'm using at the mome, don't want to drop £40 on one only to find it won't fit.

The Breathe Sweet works really well and is far less restrictive than the RAMAIR type, which IMO are normally supplied too small by most scooter dealers. Yes, they might fit but they're still strangling the air-flow!

Personally, I use the Breathe Sweet on a GP airhose and with a small plumber's angle piece between the 2, which allows the assembly to turn back and fit between petrol tank and toolbox.

I agree that they will not fit on most standard rubber mount manifolds/carbs, however, I've shortened manifolds further so that they do clear and fit under GP/S3 panels. Yes, it's a fag and means further modification of off the shelf parts, however, the Breathe Sweet is an excellent filter when you get one sorted so that it fits nicely. The Breather Sweet is a single foam layer, rather than the more restrictive double layers of the RAMAIRs but I find that this is a good compromise between filtering out most of the crap and still allowing it to breathe unimpeded.

Adam

Cheers Adam. Another thought, when using a breathe sweet or similar do you need to soak in foam filter oil like MX filters?

Scooterdude wrote:Cheers Adam. Another thought, when using a breathe sweet or similar do you need to soak in foam filter oil like MX filters?

You dont have to, but personally I use a filter oil... it catches the small particles of dust that might still make its way through

Part One of Two

(I've had to brake this Reply down into two parts to allow the images to load (three maximum))

I empathise with any apprehension about the Breathe Sweet filter but not about its ability to flow sufficiently as there are a number of respected Users that will vouch for that.

In my own case, I wanted to find an alternative purely from the reasons of the challenge & restricted budget. The ‘budget’ went out of the window, but I figure that I learnt something along the way.

Firstly, to give yourself ‘space to breathe’, as Adam has said, the inlet manifold can often be modified. The downdraft (CDC) type that I run with a Ø30 Dell’Orto VHB could not be any shorter than it is now, having been turned back in a lathe.

Next, think about this: With the experimenting that I have gone through, I know that the state of tune really has a major influence as to whether any filter &, in particular, any elbow can flow.

Even with no filter fitted, a standard (Ø22 mm Dell’Orto) bellows (modified further by cutting back) would not allow my engine to breathe. Similarly, a Ø40 mm bore Georg Fischer elbow choked my engine.

The first image is of a cut back air-cooled VW inlet connection that I grafted various filters onto. This flowed sufficiently but was difficult to get it to stay on the carburettor, despite making spacer sleeves.



The next images are of proprietary filtered elbows & a compact concentric filter, none of which proved satisfactory for my engine.



(To be continued)

(Part Two of Two)

(Continuation)



The next image worked but would not stay on simply because the rigid PVC elbow isn’t compliant enough to clamp, though I could have cut some slots to allow for that.



The final image is where I’ve got to & this flows extremely well. The elbow is a cut back silicone type that increases diameter from one end to t’other. I found that by mounting spigot rings (spacer sleeves) on the carburettor a bigger elbow could be utilised which was inevitably an aid to flow. The filter I rolled & glued into a closed end cylinder from air filter foam mounted on a stainless mesh cage.



I’m bound to repeat that the state of tune really has a major influence on the ability of any connection between the carburettor & filter to work.

If your engine is drawing a lot of air, as in the case of my own @ 241.5 cc, my logic (& as experimentation has shown!) dictates that the inlet arrangement must be able to cope, just as a decent exhaust must have a tailpipe that is not restrictive.....

I hope this helps somebody wrestling with the same issue!

Dead right about state of tune. I think there is a tendency to think that you need free breathing system regardless. Swept volume and peak useful rpm are really the deciding factors.

Changing your pipe from an ads3 to a franspeed race would very likely require a change to the induction side too. Other than jetting changes that is.