BSA A65 1970 - Can Only tick Over On Occasions

[mxkid]

Hi there,

Apologies in advance - I am a bit rusty with old bikes so if I am a bit vague please be patient with me 

I have an old 1970 BSA A65 that has been sat in the shed for many years so I have decided to get it running. My late father was big into his bikes and we built this from two bike (he was mechanical, I was electrical). Was all good back then - MOT's and rode it for many years. So far I have cleaned the tank / taps, cleaned the carb, fresh oil and petrol and have serviced the electrics (have a good spark). I'm pretty happy with how it's all going.

When I try and start it I 'tickle' the carb (elements of fuel 'seep' out as I remember from years ago) and kick her over. She tries to start then cuts out. I have managed to get her ticking over by adjusting the throttle and air screws but cuts out with throttle. I've tried with the air filter off just in case there is an issue there. I've even tried with the petrol cap off just in case there is a vacuum problem. Feels like fuel starvation to me but I don't know why. I've done all of the basic checks but have hit a bit of a wall. Before it went into storage it was running fine.

Any help / suggestions welcome - and if you need any further information please ask and I will do my best to supply. Thanks!

[idie]

 :sounds like a blocked pilot jet.

[mxkid]

Hi idie, thanks for the reply. I've taken the pilot jet screw out (and throttle) and have cleaned it as well I can  - perhaps I should try carb cleaner? Do you think it's something blocked that I can't see / can't get at?

[idie]

There are the tiny holes before and behind the slide, all connected to the idle circuit all of them can get blocked with the rubbish that's called fuel when it drys out. Sometimes the only way is to put the cards in an ultrasonic cleaner.

[mxkid]

Ah, ok - looking at the workshop manual there are three separate holes at the bottom of the mixing chamber body (I couldn't / didn't really want to remove the carb completely as it's been on there for so many years so missed that - I just took out the slider from the top and the float bowl at the bottom to do the work). Time for more investigation - I think this may be the issue - thank you @idie - watch this space 

[royblackburn1@btinternet.]

I cleaned  the tiny holes with a frayed piece of wire from cycle brake cable carefully not to scratch the inside then sprayed carb cleaner in

[mxkid]

Thanks for the ideas everyone - much appreciated 

So I removed the air filter and checked the two sperate holes at the bottom of the mixing chamber body (the workshop manual showed three but my carb has one blocked off). All passage ways are clear. I will get some carb cleaner but I'm not sure if this will help.

Feel so close to getting it running - as I said it tries to run when 'tickled' - and I have had it ticking over on the stand with no throttle. And I've tried several options with the throttle and air screws and also the choke. Are there any other parts that I'm missing that could need a clean?

[V500]

You need to properly go through the carb  and clean the pilot circuit. Concentrics often have these blocked, and sometimes it's necessary to remove the Welch plug and use a very small drill bit.
Should be lots of "how to" videos on the Net or Youtube.