correct air filter for 61 Super Rocket

[mikeb]

Hello
my new (to me!) '61 SR (UK version) has no air filter and not even a grill. runs very lean as need half choke to run when warm. I don't know its history tho this carb 389/46 matches the bike. questions:

1. having no air filter sounds crazy to me - I'm running on sealed roads/motorways... should i be concerned?
2. if i need to re-jet the 389 monobloc maybe I should sort the filter first. but I'm not sure what filter they are supposed to have, if any. one thread said with an air filter the main jet is 290, but without an air filter it's 400. that almost suggests they didn't have an air filter if 400 is the default. So what is original anyway? some possibles pictured below (old pancake, box like other A10's)
4. the most available here (in NZ) is an aftermarket pancake type.... any good?

all advice appreciated

thanks

Mike

[bikerjohndavies]

Hi Mike, I live in the UK but have a 1962 exported to the West Coast USA A10 Super Rocket on which BSA fitted the standard A10 air filter like your second picture (see picture). It has a 389/47 carb as standard which had the 290 main jet fitted. Not sure why the UK market ones ran with just a bell mouth and no filter, probably just to be a bit more racy looking. Cheers, John

[bsa-bill]

Not sure why the UK market ones ran with just a bell mouth and no filter, probably just to be a bit more racy looking.
 We don't have too many deserts in the UK and a fair amount of moisture at times so very little in the way of abrasive particles in the air, just the occasional oily rag

[Triton Thrasher]

If it needs choke to run, I suspect there is more wrong than jetting or missing filter.  Blocked pilot jet? inlet air leak?

I found those chrome grill pancake filters with paper element restrictive.

[mikeb]

thanks for the tips so far. sounds like as a UK version it had no filter - just the bell mouth. do some people put mesh bug catchers on those? we don't have deserts in NZ but lots of bugs.

I've dissembled the carb and found a 410 main jet (I think the UK version original specs for '61 SR say 420). the needle (stamped 'D') is set to the highest (richest) position.
But I can't figure out what throttle slider I have - as per the photo below the only markings are '380' and '1'. can anyone identify this?

thanks

Mike

[bsa-bill]

The standard BSA filter as in Mikes pic (bottom one) is a bit of a pain to fix on with those little screws, so I've found these
http://www.ebay.co.uk/itm/200679460800

should fit if Draganfly are correct  2BA, 3/16 BSF, M5 and 10UNF are all interchangeable
0riginals being 2BA

Will let you know if this is not the case, should be here tomorrow

[RichardL]

Mike,

The chrome grille version you're showing is intended for dual carbs, based on the offset of the threaded neck. There is also a single-carb version..

Richard L.

[bikerjohndavies]

Hi Mike, To get the cutaway number you could use this table from the Amal web site to measure the cutaway and work out which slide you have.

Stamped    Height of cutaway
2                1/8"          RICH
2 1/2          5/32"
3                3/16"
3 1/2          7/32"
4                1/4"
4 1/2          9/32"
5                5/16"        LEAN

Cheers, John

[muskrat]

A quick way of checking slide cutaways is to sit it on a flat surface and see what size drill shank will fit through the cutaway.
Cheers

[RichardL]

A quick way of checking slide cutaways is to sit it on a flat surface and see what size drill shank will fit through the cutaway.
Cheers

Way too logical.

[Triton Thrasher]

thanks for the tips so far. sounds like as a UK version it had no filter - just the bell mouth. do some people put mesh bug catchers on those? we don't have deserts in NZ but lots of bugs.

I've dissembled the carb and found a 410 main jet (I think the UK version original specs for '61 SR say 420). the needle (stamped 'D') is set to the highest (richest) position.
But I can't figure out what throttle slider I have - as per the photo below the only markings are '380' and '1'. can anyone identify this?

thanks

Mike

The problem with mesh covered bellmouths is they are restrictive, but they don't filter dust.

Could your "380" be 389, and is there a number after it?

[mikeb]

Thanks for the ongoing help…
Triton Thrasher – definitely 380, as per the pic above, with a ‘1’ stamped at the top. no other markings.
bikerjohn – I saw that table for concentrics (?)… didn’t realize it applied to monoblocs too.
muskrat – great trick… and the answer is.. 3/16 --> number 3, so that is standard.

The carb is pretty dirty. next challenge is how to get the pilot jet out as it’s stuck tight. Any tips for how to do that?? preferably without damaging it as replacements are slow to arrive in this part of the world.

cheers
Mike

[muskrat]

Try dropping the carb into some boiling water for a minute or two.
Your local blokes http://www.britishspares.com/ should have carb parts.
Cheers

[bsa-bill]

The standard BSA filter as in Mikes pic (bottom one) is a bit of a pain to fix on with those little screws, so I've found these
http://www.ebay.co.uk/itm/200679460800


arrived yesterday, needed a tap through due to rust in the threads but they fit just fine

[WozzA]

I found the original filter mentioned above a real pain in the ar$e to get on & off
so I went with a non restrictive pod filter