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Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #424995
03/18/12 10:41 pm
03/18/12 10:41 pm
Joined: Aug 2001
Posts: 3,745
argyll. scotland, uk
gavin eisler Online content
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gavin eisler  Online Content
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argyll. scotland, uk
That looks like acceptable wear on the kickstart spindle and Ive seen worse cotter pins. The pin looks like its been recycled , the face having been dressed by a bastard file. The taper should not extend to the end of the pin shaft.
If the kickstart was indeed spinning on the spindle , when the lever returned it would be way off the starting position, is this the case?
I used to source cotter pins from cycle , /pushbike shops, older bikes used these to secure pedals to the crank spindle, there are more than one size, if you take your old pin to and old school cycle shop they may have something suitable.
kommando has an excellent plan , I didnt know blank pins were available

One way to help prevent this wear is to drive home the cotter pin with a good drift before tightening the nut, after a week or so of use, drift again and retighten.

other primitive dodges I have used to get more life out of cheese like cotter pins is to case harden them by heating to cherry red and plunging into a bowl of sugar.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
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Re: 71 BSA Thunderbolt kick start [Re: ] #425010
03/19/12 12:34 am
03/19/12 12:34 am
Joined: Feb 2007
Posts: 2,213
Atlanta, GA USA
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Semper Gumby Offline
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Atlanta, GA USA
The other possibillity is that this might be a design feature.

Every now and then I go to kick the Thunderbolt (or the Firebird) and it feels like it's catch tooth on tooth (i.e. it won't kick). So I rock the bike forward a bit against the 1st gear then back to neutral and WALLA it kicks. Save a bit o wear on the spindle cotter bits kicking it when it doesn't want to. Mind you it is not slipping though....


Gaggle of BSAs
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Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425056
03/19/12 10:46 am
03/19/12 10:46 am
Joined: Dec 2004
Posts: 9,224
Scotland
kommando Online content
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Scotland
All you need to know about cotters and more

http://sheldonbrown.com/cotters.html

I bought some fully round cotters from Roy Pellett but he is currently not selling.

From memory Triumph cotters have a deeper flat on the cotter and do not grip properly when used on a BSA as the nut uses the full length before it is fully tight which looks to be the problem here.

Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425059
03/19/12 11:34 am
03/19/12 11:34 am
Joined: Oct 2001
Posts: 529
Norway
Ola Offline
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Ola  Offline
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Norway
If you have the pre 71 quadrant, and the post 71 kicker, I think you may end up like you have.
http://www.britbike.com/forums/ubbthread...3556#Post413556

Best regards


There are no bosses in a technical discussion
(Doug Hele, 1919 - 2001)
Re: 71 BSA Thunderbolt kick start [Re: ] #425089
03/19/12 3:25 pm
03/19/12 3:25 pm
Joined: Sep 2011
Posts: 49
Boulder, Co, United States
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sam_tots Offline OP
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Posts: 49
Boulder, Co, United States
When you say pull the left side engine cover off and kick it over, if the pressure plate turns but chain does not than the clutch is slipping?

Thanks,

SAm

Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425093
03/19/12 3:40 pm
03/19/12 3:40 pm
Joined: Jan 2006
Posts: 1,851
Maryland
JD Offline

Moto-Amish
JD  Offline

Moto-Amish
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Posts: 1,851
Maryland
Yes.


Josh
Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425824
03/23/12 5:36 pm
03/23/12 5:36 pm
Joined: Sep 2011
Posts: 49
Boulder, Co, United States
S
sam_tots Offline OP
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Boulder, Co, United States
Update: Just ran through the clutch test mentioned above with the side cover off and the systems are ok.


Sam

Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425828
03/23/12 5:45 pm
03/23/12 5:45 pm
Joined: Jan 2006
Posts: 1,851
Maryland
JD Offline

Moto-Amish
JD  Offline

Moto-Amish
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Posts: 1,851
Maryland
Have you adjusted the clutch rod as per gavin's post?


Josh
Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #425834
03/23/12 6:24 pm
03/23/12 6:24 pm
Joined: Aug 2001
Posts: 3,745
argyll. scotland, uk
gavin eisler Online content
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argyll. scotland, uk
So, presumably the kicker assembly is reassembled and AOk?

with the primary cover removed and clutch disengaged check that there is no wobble in the pressure plate when the motor is kicked over, this is corrected by adjusting clutch spring tension so that the plate withdraws evenly.
There is a slim possibility that the woodruff key on the clutch centre hub taper has failed/sheared, IME this gives total drive failure , not the intermittent slipping you report.

More likely is a worn out and notched clutch basket and hub, when the clutch is disengaged it fails to fully re engage because the plate tangs get hung up on the wear notches instead of completely re engaging.
DPOs may have replaced tired friction plates and springs in the past, neglecting to address other wear issues. Every part of the clutch is a wear item.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: 71 BSA Thunderbolt kick start [Re: sam_tots] #429020
04/10/12 8:15 pm
04/10/12 8:15 pm
Joined: Sep 2011
Posts: 49
Boulder, Co, United States
S
sam_tots Offline OP
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sam_tots  Offline OP
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Posts: 49
Boulder, Co, United States
OK, we are all good now! Thanks everyone so much for the help. The problem was a combination of clutch adjustment and some refurbishing of the kick-start mechanism. Starts first or second kick again and no more problems with the kick. So awesome, first ride in 6 months today, was great.

Thanks,

Sam

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