900 series carb configuration for Atlas

Hi,

Does anyone know the main,pilot jet,slide sizes etc to be used for an Atlas running a single 900 series concentric carb?

Don't worry I'll just use the information as a starting point and fettle from there.

I know this may not be correct but I've got an unworn one,nothing else large enough and little cash.

Many thanks Keith Parsons

Previously wrote:

Hi,

Does anyone know the main,pilot jet,slide sizes etc to be used for an Atlas running a single 900 series concentric carb?

Don't worry I'll just use the information as a starting point and fettle from there.

I know this may not be correct but I've got an unworn one,nothing else large enough and little cash.

 

Many thanks Keith Parsons

carbs when it was nearly standard. It had straight through reverse cone megas with minimal baffles. (The type readily available on Ebay etc).

HTH

Alan

Sounds about right - When I went from twin carb to single, I used the same jettings - didn't touch the carb and it runs absolutely fine. And I have a spare carb ready to fit when the current one wears out.

Thanks Alan, thanks Gordon,

I'll start there then.

Are you useing air filters?

No. I know I should but there's not a lot of room to fit one. Anyway, up here in sunny Scotland, the biggest problem is ingesting rain, followed by midges... and of course carb icing. The joys...

No, not using air filters.

Cheers

Alan

Remember that there are a variety of choke sizes for this series of carb.

My Atlas originally had twin 928s and ran fine on 220 main jets, with no air filter.

I then converted to a single 930 carb, without an air filter,  and was advised to use a 250 main jet. Again this seemed correct but I did frequent plug checks to make sure.

The only problem I really had was the pilot jet continually blocking and messing up the idling.

Eventually I fitted an inline fuel filter which turned out to be a smart move as it trapped huge amount of dirt in the petrol and rust from my tank.

Hi Phil, the inline fuel filter is a great idea, why didn't I think of it?!!  I used one for years, with outboard motors.   You can pick one up in any yacht chandlers, probably cheaper than from a bike shop.

That's the second good tip you have given me recently (the other re using alloy pushrods with an iron head).   Keep it up please!      John