Author Topic: Cast your experienced eyes over this... (dynamo chain)  (Read 815 times)

Offline UncleD

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1958 Super Rocket.  A new bike and model to me.  Apparently 'restored' however many bodgy jobs so not exactly to a high standard.

I had the timing cover off for the first time today (to do the timing) and found a lot of water contaminated grease in the timing chain cavity.  Should there be a lot of grease in this cavity? How does water get in (the gasket looked sound)?  (I took photos but the computer says no...they are too large).

The timing chain is slack to the extent that it has worn grooves in the top and bottom of the inner cover where it flexes outward.  Should I remove a link or is there an adjustment?

The oil around the pump was clean with no course residue (just a thin smooth film in the bottom).  Does this pump look original or has it been upgraded in the 'restoration?' (See photo)

The locking bolt in the advance /retard mechanism was quite bodged (had been rounded...and then welded into an impressionist shape that doesn't fit any spanner or socket)...I assume I can just buy and screw in a new one? (These are the little bodgy surprises I am finding everywhere).  Goodness knows why they have drilled new holes for the tacho drive as the original threads look fine. Any ideas? 

I have some other questions about adjusting points but will start a new topic in electrical.

Northern Territory, Australia

Offline Klaus

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #1 on: 08.12. 2018 08:40 »
Hello UncleD,

This chain is not for the timing, it is only for driving the generator. This chain had to be good greased, but there should be no water.

Oilpump is original and looks fine.

More pics would be helpfull.

cheers Klaus


If you think, everything is under control, you are not fast enought.

Online Swarfcut

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #2 on: 08.12. 2018 08:58 »
 
 G'day UncleD

     Here are a few answers to your questions.

   The chain which you describe as a timing chain is in fact the drive to the dynamo and is completely independent from any part of the ignition system. The chain has no lubrication, other than a reasonable quantity of grease added to the chain compartment before the timing cover goes back on. There should be no "water" in there. If you study the dynamo, you will see the armature drive sprocket is not concentric with the dynamo body. Adjusting the chain is a case of slackening the retaining strap and rotating the dynamo body in its cradle, making sure there is a good cork gasket between the dynamo and the timing case and the dynamo is pressed outboard to compresses the gasket to give a good seal.  Neglect and wear over time means most engine cases have the tell tale witness marks of a slack chain.

  The oil pump and its retaining nuts look original, but the small washers usually fitted under the oil pump retaining nuts are missing. The retaining studs appear too short. With washers fitted the nuts would be proud of the studs. Best to leave alone for now unless you want to start digging deeper. Nuts are not rounded so gives the impression of not having been apart too many times.

  Oil collects in the oil pump cavity when the engine has been run, in use the pump runs submerged to a degree in this oil (which bleeds from the crankshaft timing bush and is part of the design, so just a smooth film would indicate recent re assembly. Has it been built up and won't run, that's why you are checking the timing?

  The magneto  ATD bolt is a notorious masterpiece of crap design, and I can tell you have the positive attitude (which will soon disappear) when you come to deal with it.

  Tacho drive may have been from a different model with slightly different mounting holes. Your cover possibly amended to give a better line for the drive cable.

  I would recommend the UK based Priory Magnetos website for the answers to your ignition questions.

  You will find modern spanners do not fit any of your nuts and bolts, old style Whitworth and BSF are the ones you need. Most of the threads are CEI (Cycle Engineers' Institute) also known as BSCY. "Cycle Thread" reflecting BSA's earlier connections with bicycle manufacture.


  Good luck getting it to run.

  Swarfy.

Online duTch

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #3 on: 08.12. 2018 09:06 »
 
 Swarfo rounded me up so I'll now read his stuff.... *fight*

Yes- what klaus says it looks to be a standard pump....
Quote
.............. with no course residue.......
   I think you mean 'coarse' but I'm not here to teach spelling (no doubt a typo/spellcheck/proof-read error )  *conf*...

 The dynamo/Genny drive chain is adjusted by loosening the holding strap and rotating the genny to your desired chain adjustment...water *may* be from condensation or leaking in past the cork gasket in the end of said genny/casing interface- may be worth sliding it out for a Bo-Peep....

 what you say about the nut- yup

 That tacho drive bodge on the cover makes my bodge look good *pull hair out*

 Dontcha just love 'restorations' .... *eek*

 **edit- having now read Swarfos comment, I'll add that in my experience, spanners are in WW/BS  (BSF is thread form)
 Dunno 'bout the tacho drive *dunno* *bash*....FYI there should generally be about 70ml of oil in the pump cavity





Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online Billybream

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #4 on: 08.12. 2018 09:08 »
If you conduct a search on this forum most of your questions will be covered and you will also locate data sheets with service information.
Regarding the chain this is the dynamo drive and most will have worn the casing, adjustment is via the dynamo housing. You will discover a cork washer which acts as a seal between timing cover and dynamo and this could be the entry of moisture.
Suggest you read through some threads on this great forum and all will become easier to work out.
1960 Super Rocket, owned since 1966, back on the road 2012 after being laid up for 29yrs.

Offline UncleD

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #5 on: 08.12. 2018 09:17 »
Cheers Swarfy, Klaus and others
The bike does run...a bit tricky to start but I think that's a combination of some carby adjustments and me finding its sweet spot.

When I compare it to my rebuilt A65, it has got similar power  and pick-up with no blown smoke, major noises etc so despite the little things (like those missing washers) she appears sound.

The reason I am checking the timing is a combination of me need to KNOW things are right...and a sense that she's not quite firing as cleanly as she should (in particular a black sooty right plug and relatively clean left plug)...yes I have read about induction bias ...and will be checking the carby/ manifold join and rebuilding the carby tomorrow.

Have all manner of tools including whitworth.

I would judge there to have been a 'reasonable' amount of grease around the dynamo chaincase so will just clean and replace what was there.  I will do some research into adjusting the dynamo to take up the chain slack and also check whether the cork washer is the source of the leak (it does look a little suspect).

I do have more photos but find reducing their size more challenging than understanding magnetos!

Northern Territory, Australia

Offline UncleD

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #6 on: 08.12. 2018 09:59 »
I was just looking in the Haynes manual and the picture of the dynamo chain shows gouges in the inner cover from a slack chain! *smiley4*

Northern Territory, Australia

Online Greybeard

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #7 on: 08.12. 2018 10:01 »
I do have more photos but find reducing their size more challenging than understanding magnetos!
There is advice on resizing photos on the forum help pages. I'll go and copy the link for you. Hold on...

Here you are:
https://www.a7a10.net/forum/index.php?topic=427.0

Online Swarfcut

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #8 on: 08.12. 2018 12:52 »
 The big dynamo drive sprocket is notorious for uneven wear, so you may find you have to compromise on the chain tension. Nice tension at the tightest point, then goes all Slack Alice then tight again.

  New sprockets are a bit of a gamble, rumours of eccentric assembly and poor tooth profile. The sprocket is on a plain taper, usually comes off easy with a two jawed puller and a little smack, unless someone has played the fool and overtightened the nut. Screwdriver levers were how we did it in our youth.......some of us know better now. Originally there would have been a circular cork washer under the the sprocket, fitted as an attempt to prevent crankcase oil entering the dynamo chain compartment and to control the end float on the idler pinion shaft.

 Toothed belt drive conversions are a modern well tried and expensive alternative, which offer a greater dynamo output for a given engine speed, ideal if you decide on the 12 Volt route.

 Swarfy.

Online berger

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #9 on: 08.12. 2018 15:35 »
I went to the pub *beer* *countdown* swarfy we can  have a little game of I-SPY   ….. I spy something beginning with W ?

Online BigJim

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #10 on: 08.12. 2018 16:12 »
Is swarfy supposed to respond with What?
 *bright idea* *beer* *bash*
Jamie,  Supporter of Distinguished Gentleman's Ride

Online Swarfcut

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #11 on: 08.12. 2018 16:14 »
Hiya Bergs.....Knowing you it has to be Weather Spoons*
   
  * A popular but select UK based chain of licensed premises, noted for high quality ales and fine food.

 For more information check out American Comedy Star Rich Hall's  song "Weatherspoons" on the CD  "Working Dog"

 Swarfy.

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #12 on: 08.12. 2018 16:25 »
mmmmm :-\ here is a clue- something beginning with W and some people put clothes in them to make them clean ? as for weatherspoons I don't go there because they don't have a juke box *bash* I must check out rich hall he is good.

Online bsa-bill

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #13 on: 08.12. 2018 16:28 »
Quote
I spy something beginning with W ?

no I think as he's been to the pub what he saw was probably a V  but two of them
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Caretaker

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Re: Cast your experienced eyes over this... (dynamo chain)
« Reply #14 on: 08.12. 2018 16:57 »
Ontopic reminder for the tech boards. Thanks.
"Sometimes I say things that are so highly intelligent that I do not understand a word of it"