Author Topic: Auto advance tach drive  (Read 1005 times)

Online Seabee

  • A's Best Friend
  • ***
  • Join Date: May 2011
  • Posts: 132
  • Karma: 2
  • 1957 Road Rocket
Auto advance tach drive
« on: 29.04. 2013 12:58 »
Hi Guys,

My 57 RR has an auto advance mag.  I have finally collected all the bits for a tach set up, but wondered if anyone had figured a way to drive the tach from the auto advance assembly?  I hate to go to the bother of converting my mag to a manual advance (to get the right drive gear), but I'm afraid that may be the only solution. I thought about tapping the securing nut and adding a slotted button to drive the tach.  I wonder if this would effect the auto advance mechanisms functioning?  Any thoughts?

Seabee
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8176
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Auto advance tach drive
« Reply #1 on: 29.04. 2013 13:58 »
G'day Seabee, I think your idea sounds feasible. I can't think of any problems with the auto advance.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Triton Thrasher

  • Scotland
  • Wise & Enlightened
  • *
  • Join Date: Feb 2009
  • Posts: 1482
  • Karma: 20
Re: Auto advance tach drive
« Reply #2 on: 29.04. 2013 17:34 »
Don't do it. It will delay or prevent the ignition from advancing.

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8176
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Auto advance tach drive
« Reply #3 on: 29.04. 2013 21:00 »
 Doh, you are right TT, any drag in the tacho/cable will work against the AA.
Thats why tacho's were only fitted to the sportier models with manual advance.
My brain goes to bed a lot earlier than my body.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5920
  • Karma: 32
Re: Auto advance tach drive
« Reply #4 on: 29.04. 2013 22:08 »
Ok, shoot me down but isn't the AR retaining bolt threaded to the camshaft? If so it cannot affect the AR unit.

Offline gavinoz

  • A's Best Friend
  • ***
  • Join Date: Apr 2012
  • Posts: 140
  • Karma: 3
  • Dogs & Sheep hate smokers worse than Hondas.
Re: Auto advance tach drive
« Reply #5 on: 30.04. 2013 04:06 »
Sorry Neil,

Think you'll find that AR bolt is threaded to Magneto shaft, Cam is attached to cam Timing pinion,

gav
Rigid A7S, 57 A10 in pieces
Australia

Online Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5920
  • Karma: 32
Re: Auto advance tach drive
« Reply #6 on: 30.04. 2013 08:43 »
Sorry Neil,

Think you'll find that AR bolt is threaded to Magneto shaft, Cam is attached to cam Timing pinion,

gav

Duh! Of course, and now I can see why the tacho idea won't work. Silly me.

Note to self: engage brain before committing thoughts to screen!

Online Seabee

  • A's Best Friend
  • ***
  • Join Date: May 2011
  • Posts: 132
  • Karma: 2
  • 1957 Road Rocket
Re: Auto advance tach drive
« Reply #7 on: 30.04. 2013 12:45 »
Thanks for the feedback guys.  Unfortunately, you have confirmed my fears.  I hadn't taken the time to sort the rotation in my mind to determine if the cable drag would retard or hold the advance full on.  I hate the idea of going to the trouble of converting the mag to manual advance, but I guess that's what the bike should have had originally anyway.  It was a bitsa chopper when I bought it three years ago, and now is in excellent original condition if I do say so myself!
1961 Super Rocket
1957 Road Rocket
2009 Harley Electra Glide Classic
1993 Harley Springer Softtail
1970 Harley Sportster Chopper
1957 Harley Panhead Chopper
1982 Yamaha XT550
2001 KTM EXC 400
1970 Honda CT70
Southern Illinois, USA

Online Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 5920
  • Karma: 32
Re: Auto advance tach drive
« Reply #8 on: 30.04. 2013 12:50 »
On the plus side; Just think, you'll have a nice new lever to fiddle with! *smiley4*