The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Pecon on 31.12. 2012 22:28

Title: Movement on dynamo sprocket
Post by: Pecon on 31.12. 2012 22:28

After a recent rebuild I removed the timing cover after a couple of hundred miles to reset the timing when I noticed that there was some in and out movement in the large dynamo pully. I did not do the initial strip down, this was done by SRM who returned the engine with the timing covers disassembled so I don't know if there should have been some type of spacer or washer between the gear and the inner timing cover. I have gone through all the parts books and diagrams I can find but nothing other than the cork spacer on the breather is visable. Should there be something to take up the play?. It does not seem to cause a problem with the chain but I was thinking of fitting a belt drive and am worried that the play might cause the belt to run off.

BTW Does anybody have any views on the merits of upgrading to the belt drive and perhaps a DVR2?. I am still on 6 Volts but I am using the bike day and night with CREE 12 Volt LED running lights with a 6 to 12 Volt inverter which seems to draw the same current as a headlight but with a much brighter light.


Title: Re: Movement on dynamo sprocket
Post by: muskrat on 31.12. 2012 22:52
 G'day Peter. There should be a cork or felt (SRM use felt) seal behind the sprocket. Neither of my A's have it and only let the tiniest amount of oil in. Both are running belts (1 SRM and 1 Lytedrive) and Dvr2 in the 12 volt mode.
A little end float is OK but if the idler gear is not tight on it's shaft the shaft may creep and give excess end float or sprocket missalighnment.
Oh my head hurts, Happy New Year.
Title: Re: Movement on dynamo sprocket
Post by: Pecon on 31.12. 2012 23:57
Happy new year to you to Muskrat ( still 5 minutes to go here) I must have missed this, looks like another partial strip :-(.

Title: Re: Movement on dynamo sprocket
Post by: warmshed on 01.01. 2013 16:29
1 vote for the DVR2,   There seems to be 2 belt drives, one by the makers of the DVR2 that gives a 20% speed increase (same as mag/dyno set up) and the SRM list one with 10% speed increase. In theory I would opt for the DVR2 one the increase in dynamo speed gives a much more usable 12 volt conversion with the standard 6 volt field  and armature. Price is very similar