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pancake air filter

Posted by john_day at October 10. 2017

I have an ES2 fitted with a 389 monoblock, but no air filter.

There is limited distance between the carb 1/34 i.d inlet  and the oil tank. can anyone tell me if there is sufficient room for a pancake filter, and what type, or there any other solutions?

p.s. not a screw fitting on carb, fuel lines can move out of the way.

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Re: pancake air filter

Posted by Dan Field at October 10. 2017

I've got a different oil tank but have filter fitted, I'll post a pic shortly

Re: pancake air filter

Posted by Skip Brolund at October 10. 2017

From what I see in the pic it is a single downtube, pre-featherbad frame?

I have this same issue with my 1957 Model 77. From what I have read, it never came with a filter? I would really like to fit one, ideally vintage aftermarket, such as Vokes, rather than a modern looking K&N. I will have the same concern with a 1952 ES2 project that is coming up

Anxious to see what comes of this thread :)

Re: pancake air filter

Posted by john_day at October 10. 2017

off to Stafford on Sunday, so will be looking out for filters that might fit!

Re: pancake air filter

Posted by Dan Field at October 10. 2017

I posted a pic where did that go? This website does my head in!

It's raining so not going out to take a pic, here's one I prepared earlier!  Zoom in to see the filter, but I'm not sure if it would fit if I had the standard oil tank.

 

Re: pancake air filter

Posted by john_holmes at October 11. 2017

There are 2 main types of pancake filter, the std one with the central hole for the carb connection and the offset one where the carb connection is not central. The offset one gives more scope for fitting into awkward spaces by turning the filter before finally tightening the clamp and I have used it sucessfully where no filter was fitted previously. 

Re: pancake air filter

Posted by john_day at October 11. 2017

The offset one might well work, just got to make sure that it will fit the389........ ... 1 3/4 inch

Re: pancake air filter

Posted by Albert Sheean at October 14. 2017

Previously john_day wrote:

I have an ES2 fitted with a 389 monoblock, but no air filter.

There is limited distance between the carb 1/34 i.d inlet  and the oil tank. can anyone tell me if there is sufficient room for a pancake filter, and what type, or there any other solutions?

p.s. not a screw fitting on carb, fuel lines can move out of the way.

Apparently Norton's did have an air filter for the ES2, according to my copy of the "Spares List 1957 ES2, 19S and Model 50"

Here are some parts numbers

#19820 Air Cleaner 1 ea.

#19845 Air Cleaner Connecting Hose 1 ea.

#20139 Air Cleaner Hose Fixing Clips 1 ea.

#12342 Air Cleaner to Mudguard Fixing Bolts 2ea.

#E5379 Air Cleaner to Mudguard Fixing Bolt Washers 2ea.

#E3229 Air Cleaner to Mudguard Fixing Bolt Nuts 2ea.

#20137 Carburettor Adaptor 1 ea.

Hope this helps.

Re: pancake air filter

Posted by john_day at October 14. 2017

many thanks!

I'll have a look at Stafford tomorrow but I think my chances of getting an original are fairly remote.

will try for a pancake offset one, and if that does not fit resort to the bellmouth with gauze.

whilst on the same ish topic, has anyone fitted a 'deflector' underneath the carb to stop petrol dropping onto the magneto/dynamo?

Re: pancake air filter

Posted by Ian MacDougall at October 14. 2017

In my experience a bellmouth with gauze can present a significant restriction to airflow and noticeably reduce performance. The area of gauze needs to be significantly larger than the carburettor bore to maintain the airflow. The one I was using had a gauze diameter approx 45mm. The pre-monobloc 276 carb fitted to ES2 c1950 had a wide bellmouth with gauze as standard and is available new from Amal  http://amalcarb.co.uk/pre-monobloc/76-276-series/air-intakes/276-gauze-intake-assembly.html

I don't know if that is compatible with monobloc carbs, Amal list only a plain, unobstructed, air intake tube for the 389.

Ian McD

Re: pancake air filter

Posted by john_day at Tuesday 11:08

o.k. you get the idea, bit more work tidying it up but it does fit.

basically an offset pancake filter, used the two end plates, discarded the rest.

then cut a 1 inch strip, 377 millimetres long, formed it to fit, then a disc of fine s.s. mesh.

now to solder together, I know ss does not solder but will be held in place by 1 inch strip

Attachments

Re: pancake air filter

Posted by Ian MacDougall at Tuesday 12:21

That looks promising, would like to see a pic of the finished article. Stainless can be soldered if you have the appropriate alloy & flux. Try Activ8 acid cored 96S (96% tin, 4% silver) solder wire from Warton Metals Ltd. https://www.warton-metals.co.uk/stainless-steel.html

Ian McD

Re: pancake air filter

Posted by Dan Field at Tuesday 13:18

What’s wrong with bit of old tights and an elastic band?! Seriously though if you want an air filter a gauze won’t filter out abrasive dust.

Re: pancake air filter

Posted by john_day at Tuesday 13:47

I fitted 30 mesh which will stop most 'oh nasties'

the firm I got the mesh from supply it down to 300 but it does seem a lot less rigid.

the 30 mesh is finer than the amal bellmouth!

my mark two design has the mesh fitted on the outside of the filter...... I was worried that if the edges of the stainless mesh broke up they would get sucked into the engine!

Re: pancake air filter

Posted by john_day at Tuesday 15:13

I fitted 30 mesh which will stop most 'oh nasties'

the firm I got the mesh from supply it down to 300 but it does seem a lot less rigid.

the 30 mesh is finer than the amal bellmouth!

my mark two design has the mesh fitted on the outside of the filter...... I was worried that if the edges of the stainless mesh broke up they would get sucked into the engine!

Re: pancake air filter

Posted by ian_soady at Wednesday 10:16

One advantage of a wire mesh is that it acts as a flame trap so any backfire (what, on a Norton) will not ignite anything outside the carb.

Same principle as a Davy Lamp.

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