R51/3 air cleaner element

[Vegtamr]

OK rookie question...

What's the preferred method for cleaning the wire mesh air filter element on an early (1951) R51/3?

This is the round air cleaner with the slotted housing that you rotate to enrichen the mixture for starting.

Is it as simple as wash w soapy water/dry/treat with oil?

Thanks.

[Micha]

Good morning,
From the workshop manual:

Wash also common air filter with petrol or kerosene and re-oil metal screen after cleaning

[sherman980]

Suggestion, DON'T CLEAN THE ORIGINAL MESH, REPLACE IT! That mesh is now likely nearly 70 years old. Over time, the mesh rusts, corrodes, etc. and the strands will shed/break off into small pieces that, when inhaled, will eventually destroy your engine. With a bit of care, the original element assembly can be taken apart and the wire mesh replaced with modern oiled foam (available on ebay and elsewhere). Done carefully, the change won't be noticeable from the outside of the filter. In addition to not being a danger to your engine, it is also a much more efficient filter than the mesh ever was.

Hope that helps.
Chuck S.

[schrader7032]

Chuck do you have more specifics on making this change? Seems like I've seen something like this. What would concern me is how a foam filter can flow the same amount of air that the wire mesh did. I wonder if foam chokes off and starves the engine...maybe makes it run richer requiring carb adjustments.

[vechorik1373]

You can remove the screen, and remove the old, deteriorating filter medium, and replace it with modern foam filter material cut to fit. I have done this when there was no other choice. BUT do not overdo it. You are going to have to READ the spark plugs after you do so. If you overpack the filter with foam material the engine will run rich from the filter being too restrictive. Find thin (approx 1/4 thick) foam air cleaner material, and cut out multiple circles, so you can remove, or add layers to the filter. The first time I tried this, I had way too thick of filter material, and the plugs ran pitch black very quickly. So have several spare changes of spark plugs handy ( so you can replace fouled ones ) after adjusting the amount of foam filter material you use.

[sherman980]

Kurt/Vech,
The material I typically use is about a 1/2" +/- thick. I usually buy it off eBay (search "foam air filter sheet"). I like the light green because it is easy to see when it gets dirty. One layer is plenty, same as what is used on a typical "sock" air filter like those used on dirt bikes. Never had an issue with "breathing"/running rich, and I suspect the filtration is several orders of magnitude better than the original wire mesh. I cut the ID hole a little small so it seals against the metal tube in the center and the OD a little larger so it will seal against the edge of the outer shell of the original element. I sandwich it between the the two OEM screens (cleaned and repainted). As illustration to yourself about the mesh deteriorating, when you take the old filter apart, do it over a white piece of cardboard. You will be surprised by the nastiness left behind. Found a nice pic of the one on my R68 (stock carbs, jetting, etc.)