Author Topic: Vibration-causes?  (Read 5111 times)

Online metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 652
  • Karma: 9
Re: Vibration-causes?
« Reply #30 on: 11.11. 2012 23:28 »
Glad you have finally found it! *clap* And glad it isn't something dreadfull. Well done Pal! *beer*
Good Advice
0
No reactions
England N.W
1960 A10
England

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #31 on: 15.11. 2012 22:46 »
Sent my dynamo to Priory magnetos and it is now winging its way back sporting a 12 volt armature/field coil. The previous reg had allowed the dyno to get so hot that the shaft expanded and split the bearing inner race hence wobbly banging about. Speaks of the quality of the Priory parts that the solder did not melt and it was still giving a a great charge.
Andy
Good Advice
0
No reactions

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #32 on: 19.11. 2012 08:48 »
Back on the road this morning running fine only finished rebuilding her last night at 9. Still the main vibration-footrests and a**e-but at least I know it's not the bottom end. It has lost some of the really harsh vibration from what I now know was the armature trying to bash it's way out to freedom. It got a de-oiling and new gaskets checked the timing and found the points gap way too tight. Got to work and remembered I had not tightened the drain bolt on the SRM sump plate,it was still there, phew, got to tighten that up at dinner time.
I suppose the gear box might need some new bearings??
Andy
Good Advice
0
No reactions

Online metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 652
  • Karma: 9
Re: Vibration-causes?
« Reply #33 on: 19.11. 2012 17:18 »
Keep at it Andy, you'll get there!
Good Advice
0
No reactions
England N.W
1960 A10
England

Offline wilko

  • Resident Legend
  • *****
  • Join Date: Mar 2010
  • Posts: 681
  • Karma: 4
Re: Vibration-causes?
« Reply #34 on: 19.11. 2012 21:47 »
Time to pull it down again and get it re-balanced!
Good Advice
0
No reactions

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #35 on: 19.11. 2012 22:29 »
Love to but I use her every day for work and there are no engineering shops near by. Why or how can a crankshaft become unbalanced overnight?. No signs of damage,no change ie pistons,conrods could it not be the gearbox??. Another issue tonight(easily sorted) rear brake seized took apart and reassembled in 35 mins *smile*
Good Advice
0
No reactions

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #36 on: 20.11. 2012 16:16 »
Just to cover myself I have been asking locally for firms to balance the crank. One has come back with a quote for £105+ vat. I need to tell them what the balance factor is, so opening a can of worms here what is the factor for a BSA A7 pre-unit crank standard road going??. The firm I enquired with is Julian Godfrey at Heathfield,Sussex anybody used them?.
 I will be popping into a more local to me firm Goodland engineering but I am not holding my breath they seem to dislike small jobs. I will continue to hunt the issue but when its ticking over first thing in the morning and in neutral,the bike shakes and I would say that rules out the box?. As it warms up the shakes/vibration are improved and it is happyist at 45-50 mph. But push it up the rev range and the vibration returns.
If the crank needs a re-balance what would push it out of balance as I have owned this bike for 20+ years so its not unknown history to me. This is its third crank as the first was just worn out,the second balanced by fred cooper and broken by me,the third from Yeomans over ten years ago.
Andy
Good Advice
0
No reactions

Offline Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1488
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Vibration-causes?
« Reply #37 on: 12.12. 2012 01:31 »
Short answer is that an engine cannot become unbalanced unless the reciprocating weights have changed (eg fitting heavier pistons), so doesnt sound likely. Wear will alter where resonances will make themselves felt.
Keep listening to it, it is trying to tell you something is wrong. Now what that is ... hmmm
Good Advice
0
No reactions
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8476
  • Karma: 111
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Vibration-causes?
« Reply #38 on: 12.12. 2012 08:14 »
An old bloke always told me to let it develop. Catch it before it goes pop. *eek*
Cheers
Good Advice
0
No reactions
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #39 on: 12.12. 2012 16:30 »
Problem is each day its different there is the usual footrest and seat vibes but they vary how violent. Now its taken to spitting/hesitating as put the power on(worst in the cold,cold days we are having at the moment -6 this morning).If its not one thing its another. I am aiming to have the crank balanced as when I rebuilt her after the broken crank I just bought a crank and threw it in. Yeomans aranged the grind which has stood up well in 9 years with no noticible wear.
Good Advice
0
No reactions

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8476
  • Karma: 111
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Vibration-causes?
« Reply #40 on: 12.12. 2012 18:25 »
 Do you have a choke fitted? Spitting back is usually lean mixture. Cold weather usually needs a richer mix as well. Try running with the choke on a bit.
Cheers
Good Advice
0
No reactions
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online metalflake11

  • Resident Legend
  • *****
  • Join Date: Aug 2012
  • Posts: 652
  • Karma: 9
Re: Vibration-causes?
« Reply #41 on: 12.12. 2012 20:37 »
It is so cold here at the moment the carb might be freezing. My local forecast for my surrounding area is -6c.
Good Advice
0
No reactions
England N.W
1960 A10
England

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #42 on: 12.12. 2012 22:11 »
Yep I have a choke I will give that a try tomorrow-I forget its there. The carb did stick once this morning could have been ice.
Good Advice
0
No reactions

Offline BSA500

  • Resident Legend
  • *****
  • Join Date: Dec 2007
  • Posts: 705
  • Karma: 4
  • Tonbridge,Kent,UK
Re: Vibration-causes?
« Reply #43 on: 13.12. 2012 09:00 »
Run it with the choke and it was a little improved but did still spit back/hesitate etc when putting the power on(didn't have a chance to fully test as the roads were a little tricky this morning  *eek*). I might have to look into a new needle and jet and perhaps a slide??. Vibration is still horrible and the clutch is dragging. It has new chainwheel,hub and friction plates and was great until I took it apart to sort out the engine and now a pain. I give up :!
Good Advice
0
No reactions

Offline muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8476
  • Karma: 111
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Vibration-causes?
« Reply #44 on: 13.12. 2012 09:28 »
 What sort of carb? Could it be sucking air at the flange? Can you lift the float height? New adjustable stay up floats for monoblocks and concentrics are much better than the old plastic ones. You might have to get someone else to look at that clutch, vibes could be there.
Cheers
Good Advice
0
No reactions
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7