Won't Go

[neil1964]

I would buy new Premier 930s from Amal with the new material bodies and brass slides with the jets etc to OEM spec.

https://surreycycles.com/carburettors/mk-i-600-mk-1-900-concentric/

[Rob Neal]

To wrap up this current saga I bit the bullet and bought a new pair of carbs.  Couple of kicks and away it went.  Revs nicely and has a good oil return to the tank.  Just a few finishing bits 'n pieces to figure out and it'll be on the road.  Thanks again to everyone for the advice and encouragement.  Rob

[Rob Neal]

It runs!!  I eventually bit the bullet and bought some new carbs.  A few kicks to prime things, switch on the ignition, hefty swing on the kickstart and away it went.  Sounds really nice, top end a little tappety but so pleased it runs. There's a few things to sort out carb wise as it's reluctant to start from cold but it's a good base to start from. May even be able to 'tax' it (zero £'s) from August 1st  and take it on a run. Thanks for your patience and help. Rob

[neil1964]

Excellent
Which carbs did you go for?
Stock spec?

[iansoady]

You could tax it straight away as it doesn't need an MoT.....

[Rob Neal]

Sorry for the response delay.  I eventually went for the Wassell carbs.  Only because my BSA parts and advice guru has sold loads of them and uses them on his bikes with little problem.  I managed to get them for £100 each rather than £250 ea being asked for the Amals.  I'm almost out of cash on this project!! Time will tell if i've made the right choice.  Before fitting I stripped them down and blew out all the passageways with an airline, all seems clear.  Initial starting was tricky but once running ticked over and revved nicely.  A pig to start though.  I hadn't realised that there needs to be a link pipe between the two inlet stubs to which the carbs are mounted. I'd thought these were take off points for vacuum gauges when balancing the carbs, so I'd blanked them off. Doh!  With the link in place the engine starts easily.  I'm still mystified though.  I've worked on lots of bikes over the years (all Japanese, German and Italian as it happens) and had not come across this layout before.  How does it work as surely the piston on the induction stroke is able to draw mixture from the opposite carb across the the balance pipe.  Or is it something more complex involving pressure pulses, harmonics etc?  Be interested to know if there's a technical article in the club archives somewhere that explains this.  Bike would have had its first road test this weekend but I decided to "nip up" the rev counter cable nut onto the adaptor boss on the timing case.  You guessed it....too many weetabix that morning and I snapped off the boss.  Of course, despite all of the spares I inherited with the bike there wasn't one of these in the "useful bits" pile, so waiting delivery of a new one.  But I'm so relieved that the engine runs OK, I can accept a little set back like this!! 

[iansoady]

Norton Commandos had a similar link pipe.

[V500]

As did OIF Bonnies.

[Steve.S]

i broke down in my car many years ago.
luckily i was in the AA
he arrived and looked and hummed and ha'ed and tinkered and fiddled.
after a while the guy asked me to turn the key...started first time
'what was it? what did you do?' i asked
'SH*T in the carb' he answered
as i drove off i just couldn't understand why SH*TTING in the carb sorted the problem but i'm glad it did

...the old 'uns are always the best. i'll get me coat

Bob, I do hope your Motor Car had a downdraught carburettor. It would make the whole job that much easier.

[cornishbob]

and a paper filter might be helpful

[Tigerfeet]

Not sure if this was covered earlier. To start from cold: Tickle until the fuel comes out of the carb. With the ignition off, kick over once to lay a trail of fuel into the carb. Turn the ignition on, and it will start first kick.

[Rob Neal]

Thanks for the starting tip.  As a BSA ( and Brit bike in general) newbie, starting the bike consistently has been something I haven't mastered yet.  Sure it will be now though !!