Amal Mk2 air filter...which one?

I will be fitting 2 X Amal Mk2 carbs to my Commando (carbs not fitted yet) and have just telephoned RGM to order 2 X K&N air filters and they inform me that they will press against each other as thew carbs are physically bigger, and that the carbs will need splaying slightly, and so I have put off my order until I know what I am doing/best options.

I understand that they are physically bigger, but just wondered if anybody on the forum who has fitted 2 X Mk2s before can tell me what type of air filter that they have fitted and how they "splayed" the carbs. Presumeably by slightly machining the faces of the inlet maniflods.

I have considered velocity stacks, but the Amal Mk2 type don't even have any mesh to stop large objects getting sucked in (as once happened to my friend and ended up with a bent valve and damaged valve seat). Are there any other options that I have forgotten?

So advice and experiences welcomed.

You don't have to splay them you do need to file off the unused casting bosses for the idle adjustment though.
If you turn down the O.D. of the removable bell mouth and do a little notch on the oil tank you can have this set up.

Back in 2004 I wrote this still works today.
post825.html#p825

Norbsa, thank you for that info and link.

I've already filed the castings off the inside of the carb bodies. I had wondered if it was going to be necessary to support the carbs and you have answered that question.

What I am worried about is putting a dent in the oil tank. As the engine isn't yet quite in the frame and I don't have the air filters, it's hard for me to imagine exactly what size dent you're talking about. Also, I don't feel confident taking the hammer to my oil tank. Can you explain how you did it without damaging other parts of the tank/ and impart any special metal bashing knowledge to me?

No Hammer work.... Bend a piece of 16 gage steel at 90 degrees say 2 inches wide make the legs 3'X3'. When motor, oil tank and carbs are mounted just go in with a marker leaving an extra 1/4' around the air cleaner. Cut into the tank one way with a dye grinder using a 1/32X4 inch cut off wheel. Than cut 90 degrees to the first cut. Now fit and weld the patch you made earlier cutting off the excess. I only loss about two table spoons capacity because most was air gap in the tank.

I used S&Bs they are taped towards the end and fit my Mk3 with plenty of room without modifying the oil tank. I have now splayed the manifolds, though initially I did it as NORBSA.

Cash

Norbsa, I see how it's done now, I'm not really a big hammer man I just don't have many fabricating skills.

Cash, I'm fitting 2 X 34mm Mk2 Amals, is this the set up that you have? If so, can you give me the part No. for the air filters that you have. If I can get away without modding my oil tank, all the better.

I had K&N make a dual inlet one for me a long time ago, I don't think the 2 x conical option was around then. Bit of a squeeze to the oil tank but no filing or cutting needed except to shorten the filter inlet stubs slightly. The conical ones seem to fit past the oil tank nicely to get more filter area in.
The more usual dual inlet solution is to take the one designed for the standard MK1's and machine down the bellmouths but this seems very messy to me and would cut into the ports and screw holes.

The earlier comment about filing the castings back to get the carb bodies parallel is correct. I also made up compact elbows to replace the breather stubs which also hit each other.

Rich_j wrote;

I had K&N make a dual inlet one for me a long time ago,

Click to expand...

Rich was that made to measure at the factory direct or through a supplier?

When I get the Norton built and running (hopefully in the next 2 weeks) I will go to one of the local K&N outlets and see what they have in stock or if they can advise. I would prefer to make no modifications if at all possible, but at the moment as I cannot physically see how big or small the space is, so I cannot easily proceed.

I have looked online for S&B air filters (as used by cash) but as far as I can see they only have outlets in the U.S. and not the UK.

Because I couldn't find anything in the catalogue to fit I emailed to see if they had anything else not listed, the answer came back no.
What I actually wanted was a combination of parts from two different standard filters so after we'd been through all standard stuff I just asked if they could make a 1 off special, answer was yes, send us a sketch.
Sent off a sketch, got a quote, bought a filter... big smiles all round.

I've lost all the e-mail correspondence from back then so can't give details of exactly what I asked for but I could probably reconstruct it working back from the filter if anyone's seriously interested.

This was all dealing direct with K&N in USA not through dealers.

Reggie,

I run twin 34 Mk2s. I bought the S&Bs from Lakeland Motorcycles at Pica some years ago, sorry but I can't remember the part number. I did have to open up the filter mouths though.

Cash

Reggie,

There are a few in the UK that sell S&B here's one www.ebcbrakes.com/motorcycle_brake/...p ... etor.shtml RC98 is probably the type I use.

Cash

Thanks for that cash. Their site gives all of the dimensions and so I should be able to work out the best fit.

Sorry to keep going at you, but RC98 filter is shown as the the oval type not parallel? I assume that you have an "oval" type.

They actually list an RU99 "special Norton filter" which is the parallel type, but this is probably for the standard amal MK1 32mm carbs. I will give them a call on my next day off, and find out.

Thanks again to everybody for all of the help.

the procedure for cutting down the K&N tapered air filter that fits the Amal MKII and Mikuni carburetors when twin Mikuni carburetors are mounted on a Commando. This also can be a problem when twin Amal MKII carbs are mounted, but mainly pertains to Mikuni carburetors. The problem with mounting twin Mikuni carbs has been finding good air filters to fit since the Mikuni carb is fatter than the Amal and has to have manifolds that splay the carbs apart.Can discount filter do this?

Hi , for my twin Mikuni VM34 , I had some success with two UNI filter , designed for a Yamaha 650 XS, they were fitted on my Norton cafe racer , and yes they were a bit splayed outwards.......