Author Topic: Auto advance sticking  (Read 569 times)

Online orabanda

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Auto advance sticking
« on: 20.11. 2011 12:30 »
Hi all,
I am in the process of fitting a re-furbished auto advance unit.
The repairer replaced the (failed) fibre gear, and reduced the excessive play in the counterweight pivots (bronzed up and re-drilled).

Before fitment to the bike, the auto advance returns freely; looks a good job.

However, when tightened up on the maggie, the auto advance does not return freely; it needs finger pressure to close.

I have been unable so far to find a reason  for this, and can't recall seeing this happening with my other A10s.

Do I have a problem?

If so, any ideas what could be causing it?

Richard

Online bsa-bill

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Re: Auto advance sticking
« Reply #1 on: 20.11. 2011 12:58 »
Hi Richard
I had this problem (one of many) when building the last bike, I swapped the A/R unit with one off my Flash which was a refurbished unit and worked fine and returned freely, however when put on the bike I was building it did exactly the same thing, turns out it's not the A/R that sticks it's the magneto (point of maximum flux maybe?).
However it worked ok when the engine was running as could be seen on a timing disc where the timing would flick from advance to retard with a blip of throttle
I did wonder if this was the cause of some of my starting problems but discounted it as the bike was not prone to kick back and was difficult to start with either of my two magnetos on
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online orabanda

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Re: Auto advance sticking
« Reply #2 on: 20.11. 2011 13:11 »
Hi Bill,
Your comment is appreciated; I had come to the same conclusion that the resistance of the magneto was a contributing factor.

As you point out, using a timing light will prove whether the advance is working whilst running.

I owe you a Mars bar!

Richard