Author Topic: Kickstart ALWAYS jams, SOLVED  (Read 498 times)

Offline Peter Gee

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Kickstart ALWAYS jams, SOLVED
« on: 28.08. 2019 20:06 »
Please see last post by me in this thread for my solution Sorry to revisit a dead horse... My A7SS rebuild  in deepest Africa has gone very well-- and the bike  as received had never been opened, so most parts were good to very good, considering. And it did not come in bits, but as a whole bike. Gearbox rebuild was a breeze, and works really well..... but for the dreaded kick start  jamming.

Not sometimes!Every time!

I have followed various threads on here and Britbike. One guy recommended shaving down the first quadrant tooth a la Triumph. Others said "get a pointy ratchet pinion. Someone suggested rebushing the cast iron KS bush. Another suggested re-bushing the  ratchet pinion.

Facts are simple. If they had jammed on the showroom, now a single A7/A10 would have been sold.

There must be an answer given this seems quite a common problem.

Any clues gratefully accepted as this bike is entered in a fast looming international show.

Online RDfella

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #1 on: 28.08. 2019 20:56 »
Ist things first - the gearbox was rebuilt - maybe not such a 'breeze' after all. What new parts were fitted?
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline Peter Gee

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #2 on: 28.08. 2019 22:33 »
Bearings, not bushes...all the rest seemed simply worn within tolerances, nothing graunched or sloppy.  But maybe a combination of small errors?

Online muskrat

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #3 on: 28.08. 2019 23:25 »
G'day Peter.
A worn pinion bush is mostly to blame. A worn k/start bush compounds it.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Swarfcut

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #4 on: 29.08. 2019 08:57 »
Although looking similar, the tooth profile of the quadrant and pinion were changed in 1955. So possible the box has been assembled with a pair of miss matched early and later parts, which differ in the tooth profile with either the so called pointy or flat topped teeth.  Later quadrant is 42 3160, match with pinion 67 3376. Have a good look at the mesh and tooth profile of these parts. All standard quadrants have the leading teeth relieved to aid engagement.

Swarfy.

 

Offline coater87

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #5 on: 29.08. 2019 13:37 »
 Peter,
 These bikes you "rebuild" for international shows, do you actually use them or are they just for shows?
 I have not run into an A series gearbox that did not need a new lay shaft blind bush, and at least a good rub with an external hone to smooth out the corn cobs on the shaft itself.
 I am just confused on the hows and whys of a show bike rebuild I guess. *conf*

 Lee
Central Wisconsin in the U.S.

Offline Peter Gee

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Re: My Kickstart ALWAYS jams..59 A7SS
« Reply #6 on: 29.08. 2019 13:54 »
I actually do use them, after the show which is a competitive one....
The bush was actually in  good condition so I left well alone...the box works great. I rebuild to work as good as new in all components needing  it.

To finalize this bike I have had to source parts from Kenya, Sweden, the USA and Zanzibar!

I have driven her and it's my first A7SS,  sweet bike is it.. really smooooooooooth and gentle.... very little vibration, gearbox  nice, some leak probs but all in the Chaincase and oil tank unions... am fettling it now.... so the always jamming K/S

Offline Peter Gee

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Re: Kickstart ALWAYS jams, 59 A7SS ,CLUES & PROGRESS
« Reply #7 on: 01.09. 2019 20:27 »
On the way to solving the jammy KS, I found clues after re-opening the out GB shell and decided to blueprint everything:

* Ratchet  bush 67-3169  IMO  loose both on the KS mainshaft end , with is 0.750" a.n.a (as near as, since it has to push fit at least onto the KS end bearing)  yet I am measuring bush ID at 0.738~41 giving between 0.0012~0.009" play

*Ratchet bush 67-3179 OD is also very loose on the ratchet, whose  ID is  0.930" a.n.a. Measuring the bush OD at 0.0924 so that's 0.006" play.

Weirdly, it shows no signs of wear or grooving on the OD. Hence an important ? below

I am presuming these run a max clearance of about 0.001" on both OD and ID, giving 0.002" total? Anyone know the actual clearances of these  parts?/color]

* KS  Outer cover bush is in BSA factory figs (only just obtained from Dutch BSA owners club site)   and ID 0.749~0.750.  But my quadrant 42-3160 is 0.733~0734 on the outer (kick) end. Max 0.016" play

* KS Inner bush on factory figs is 0.561~0.563. But the smaller shaft of  my KS quadrant  is 0.550~0.552/ Max 0.011" play

Again, weirdly, the KS quadrant shows no signs of grooving or stepped wear at all.

Any one of these errors, maybe two of them, would not IMO lead to the dreaded "jamming" - but when added all up, they are quite something in terms of sloppy play.

Sadly BSA does not publish all sorts of figures that would help insofar as factory ODs etc...





 

Online ironhead

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Re: Kickstart ALWAYS jams, 59 A7SS ,CLUES & PROGRESS
« Reply #8 on: 02.09. 2019 00:24 »
On the way to solving the jammy KS, I found clues after re-opening the out GB shell and decided to blueprint everything:

* Ratchet  bush 67-3169  IMO  loose both on the KS mainshaft end , with is 0.750" a.n.a (as near as, since it has to push fit at least onto the KS end bearing)  yet I am measuring bush ID at 0.738~41 giving between 0.0012~0.009" play

*Ratchet bush 67-3179 OD is also very loose on the ratchet, whose  ID is  0.930" a.n.a. Measuring the bush OD at 0.0924 so that's 0.006" play.

Weirdly, it shows no signs of wear or grooving on the OD. Hence an important ? below

I am presuming these run a max clearance of about 0.001" on both OD and ID, giving 0.002" total? Anyone know the actual clearances of these  parts?/color]

* KS  Outer cover bush is in BSA factory figs (only just obtained from Dutch BSA owners club site)   and ID 0.749~0.750.  But my quadrant 42-3160 is 0.733~0734 on the outer (kick) end. Max 0.016" play

* KS Inner bush on factory figs is 0.561~0.563. But the smaller shaft of  my KS quadrant  is 0.550~0.552/ Max 0.011" play

Again, weirdly, the KS quadrant shows no signs of grooving or stepped wear at all.

Any one of these errors, maybe two of them, would not IMO lead to the dreaded "jamming" - but when added all up, they are quite something in terms of sloppy play.

Sadly BSA does not publish all sorts of figures that would help insofar as factory ODs etc...

Looks to me like you've answered your own question.
You've got a total of 0.045" wear in there. ( F****D). All the bush I/D sizes will be std inch sizes ie: inner bush I/d = 9/16"(0.5625"), outer bush I/D = 3/4". The running clearance ( which will vary according to the end purpose)was set buy grinding the shafts to suit ie: 9/16" minus 0.002" = 0.5605."
Same with all the others.
Your K/S shaft is definatley worn or a P/O has played with it. IF the shaft is round the full length of the wearing surface & NOT tapered you can use it by making undersized bushes. Simple.  Same goes for the K/S ratchet bush but the inner of that one needs to jus be a sliding fit on the main shaft ie: + 0.0005" ~ + 0.001". O/D - 0.002".
Hope this helps
Ironhead.
SA

Offline Peter Gee

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Re: My Kickstart ALWAYS jams, 59 A7SS ,CLUES
« Reply #9 on: 02.09. 2019 07:41 »
Thanks Ironhead..I have answered my own ? finally by tracking down the info and then measuring everything carefully

Online ironhead

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Re: My Kickstart ALWAYS jams, 59 A7SS ,CLUES
« Reply #10 on: 02.09. 2019 08:54 »
finally by tracking down the info and then measuring everything carefully

Yep.
SA

Offline Peter Gee

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Re: Kickstart ALWAYS jams, SOLVED
« Reply #11 on: 05.09. 2019 18:30 »
So it turns out a number of problems with my KS mechinism, some relevant to jamming and others not, and finally solved.

1) Ratchet gear 67-3376: My actual ratchet-gear teeth are  really worn down by like a millimetre. They look rough and slightly mashed about. I thought this would prove very relevant.

2) The ratchet  bronze  bush 67-3169 had a lot of play both  on the mainshaft and between it an the ratchet. Talking of a combined 8 thou or so.

3) The Main KS steel bush   in the outer cover, a  b@tch to remove involving a stout press with simultaneous heat, also had significant play on the KS shaft. It's ID should be  a thou max  over of the KS shaft whose factory dimensions are 0.7455~.7500, It had about 10 thou play.

3) The least play was in the blind KS smaller bush, nominal ID 0.561~563. This was about 4 thou over, but being I did not have the correct blind bush puller, I decided to deal; with items 2 & 3, whilst awaiting a new ratchet gear from UK. Assembly with new KS large bush and new ratchet pinion sleeve bush might prove the problem was solved.

This proved the following:

1) My clapped out ratchet pinion teeth, though they  looked bad, did not matter.

2) Nor did the small inner kick start quadrant steel bush.

All that needed changing was the  ratchet  bronze  bush 67-3169  and the large steel KS bush 67-3153. In fact I had custom ones made then lapped and honed them manually  to close tolerances on the quadrant shaft and mainshaft and between pinion and OD of the bronze bush.

It would seem these are the two key components to carefully blueprint, and the major cause behind KS jams.

Online Greybeard

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Re: Kickstart ALWAYS jams, SOLVED
« Reply #12 on: 05.09. 2019 18:44 »
Great! It's very satisfying to sort a problem, isn't it?  *smile*

Offline a10gf

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Re: Kickstart ALWAYS jams, SOLVED
« Reply #13 on: 05.09. 2019 21:35 »
Congrats. & very nice when one takes the time to post detailed story of work and results. Thanks.

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Re: Kickstart ALWAYS jams, SOLVED
« Reply #14 on: 05.09. 2019 21:57 »
G'day Peter, thanks for posting.
I have found the pinion bush is the main culprit but a new one will only last so long if the other bush's aren't addressed at the same time.
A while back there was a bad batch of pinions that needed a special bush to match. I can't remember if it was big or small.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7