BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: ramwing7 on 09 November, 2019, 23:49:59

Title: Won't start sorta
Post by: ramwing7 on 09 November, 2019, 23:49:59
I recently went into the ignition side of my 1969 A50 to replace the ball and spring behind the oil pump in hopes of slowing down it's wet sumping.
After putting things back together and readjusting the Wassell ignition to the specs in the instructions, it won't start.

I tickle the carb and give it a kick and it fires about 3 times and then nothing until I tickle the carb again.  I get the feeling that it would do that all night long if my leg would hold up.
I've quadruple checked the alignment marks on the ignition unit and they are spot on.  I used the tool that locks into the flywheel to locate TDC.

Before I started all this, it was a reliable 2-3 kick starter

Would timing cause this phenomenon?

I ask because in installing the new ball and spring I removed the cam idler gear and checked multiple times that the marks were in alignment. (Although the bleeping timing gear has two scribe marks opposite each other)  Could I have picked the wrong one?
Needless to say, I'm getting myself more confused and I'm not looking forward to going back in.

Can anyone help out here?

Thanks.
Ron
Title: Re: Won't start sorta
Post by: chaz on 10 November, 2019, 07:29:51
presumably motor not turned over whilst cam removed so have you re checked valve clearances.
other options maybe electrical connection and earthing out on the ignition area
Title: Re: Won't start sorta
Post by: Mike Farmer on 10 November, 2019, 09:10:30
 :) :) :)

The fact that it fires would SUGGEST that there can't be anything wrong with the timing. Unless the electronics are up the creek.

Mike 8) 8) 8)
Title: Re: Won't start sorta
Post by: chaz on 10 November, 2019, 17:31:49
bearing in mind that the carb needs vacuum to suck the fuel mix into the chamber, I would go for valve clearance. its only firing 3 times may not be enough to draw required fuel in hence tikling/flooding with more fuel
Title: Re: Won't start sorta
Post by: ramwing7 on 10 November, 2019, 23:37:50
That does make good sense.
But what mystifies me is why it would go from being a very nice running bike to one that won't start when the only thing that I changed was the ignition?
I did have top turn the cam shaft go get the timing marks to line up.  Could that be it????
 :o
Title: Re: Won't start sorta
Post by: chaz on 11 November, 2019, 08:15:42
Ive had trouble before with timing 180 degrees out, pays to check it is the right firing point
Title: Re: Won't start sorta
Post by: Bess on 11 November, 2019, 09:35:45
Hi,
      Don't laugh but, here's my experiences with your symptoms:

Not enough fuel in the tank, fill tank
Blockage in fuel line, open taps and blow in tank fill hole to pressurise tank if engine starts better clean fuel lines and jets

Best wishes..
Title: Re: Won't start sorta
Post by: ramwing7 on 21 November, 2019, 15:56:06
Welp, Bess.  Your clue turns out to be the closest to defining the problem.  After testing Einstein's maxim that doing the same thing over and over again with hopes of a different outcome is a test of one's sanity, I finally gave up on the ignition line of thinking I was pursuing.  I turned to the fuel system and took off the gas tank and hooked up an IV line.
Thing started right up!
The best conclusion I can come up with is the old filter screens on the ends of the petcocks (I don't know if this is the "proper" designation) were partially clogged.  As a result they were passing some fuel, but not enough.
Long story short; new petcocks solved the problem.
Thanks top all.
Ron