The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: sean on 16.04. 2020 19:17

Title: auto advance question
Post by: sean on 16.04. 2020 19:17
my mag  (1962 super rocket ) has a fibre gear with the centre hub riveted ( 4 ) rivets is there an auto advance unit between the riveted plates  ?
Cant seem to find any info in the service sheets or parts manual .
thanks
Title: Re: auto advance question
Post by: bsa-bill on 16.04. 2020 19:28
Super Rocket would have manual advance / retard (lever on handlebar) so no a/r unit
Title: Re: auto advance question
Post by: sean on 16.04. 2020 19:35
no advance retard lever on this one looks like the hole for the cable is plugged off , which is why I wondered how the advance retard could work as the gear and hub are fixed together with the rivets .
Sean
Title: Re: auto advance question
Post by: bsa-bill on 16.04. 2020 19:59
62 A/R unit should look like pic1, however, pic 2 shows what I believe is a pre unit (or Triumph) A/R unit
 very possible it has been swapped at some time for some reason, if there is an A/R unit in there then the cog should move a short distance without the maggie moving

Title: Re: auto advance question
Post by: sean on 16.04. 2020 20:20
thanks ...just shipped it out for rebuild I will see what the guy says when he checks it out ......who knows what happened to it over all these past years
been confusing as I know srm does an aluminum gear to replace the fibre one but there is no advance retard unit on that either .....so I was wondering how the advance retard was controlled .
Sean
Title: Re: auto advance question
Post by: berger on 16.04. 2020 22:01
sean I think all super rockets were fitted with k2fc - manual operated competition magneto hence no auto unit on mag gear
Title: Re: auto advance question
Post by: bsa-bill on 16.04. 2020 22:18
Quote
so I was wondering how the advance retard was controlled

by cable from lever to the cam ring in the maggie, the cable just rotated the cam ring thereby altering the timming
Title: Re: auto advance question
Post by: Triton Thrasher on 17.04. 2020 08:35
It was not unusual for owners to do away with timing variation, whether manual or centrifugal and run with timing fixed at full advance.

There were also plenty riders who never touched the spark lever on the handlebar.
Title: Re: auto advance question
Post by: beezermacc on 17.04. 2020 09:26
A good arrangement on a Super Rocket is to retain the original magneto with manual advance & retard and to fit also an automatic ATD. Normally, with this arrangement, you would leave the handlebar lever in the full advance position at all times. When Super Rockets were new 101 octane fuel or higher was readily available at the pumps and it contained lead. This is what prevented knocking / pinking which often occurs when an engine is under load. If your Super Rocket has an ATD it will do all the usual timing adjustments you need, i.e retarding at tickover and at startup and will go to full advance as the revs rise but, once on full advance, cannot do anything about pinking under load maybe when you hit a hill or decide to give it fistfull. A manual arrangement provides a sort of ATD overide which enables you to retard the timing by way of the handlebar lever when under load with cr4p fuel if the bike pinks.