Author Topic: bsa a10 timing cover  (Read 425 times)

Offline marvic

  • A's Best Friend
  • ***
  • Join Date: Oct 2019
  • Posts: 30
  • Karma: 0
bsa a10 timing cover
« on: 07.10. 2020 21:00 »
Hi all, so i had to remove the timing cover so i can replace the srm belt for the dyno because it was worn out. When i closed the timing cover back and rode the bike i noticed that i'm getting an oil leaking from top of the timing cover where  the dyno cork gasket is, i beleive that it's leaking from where the dyno gasket is. I never had oil leaks from there before i had it open to change the belt. By the way i also had to turn the dyno a bit so the belt can get a little tighter. Any thoughts on this please? Someone told me that the oil is not suppose to travel up where the dyno belt is and just stays where the oil pump is.

Thanks.

Offline bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5557
  • Karma: 65
Re: bsa a10 timing cover
« Reply #1 on: 07.10. 2020 22:35 »
no there should be no oil in that compartment, it can come through from the idler gear if the cork gasket behind the large dynamo belt pulley is not tight up against the bush or (or in a recent post) the bush has the wrong scroll.
If I've time Ill search for the post
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

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5263
  • Karma: 50
Re: bsa a10 timing cover
« Reply #2 on: 08.10. 2020 01:00 »
Bill,

You've got me on this one. Why would oil enter from behind the idler if the dynamo is not tight up against the rear timing cover?Not saying it's not coming from behind the idler, but I might also suspect a bad seal at one of the thin bridges between the oily zones and the greased zone.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5557
  • Karma: 65
Re: bsa a10 timing cover
« Reply #3 on: 08.10. 2020 11:01 »
The two bushes that support the idler on each side of it's spindle gear have a scroll designed to scroll any oil in them back to where it came from, in the case of the one behind the dynamo gear this is back towards the idler gear and away from the dynamo gear.
there was apparently a batch made with the scroll the wrong way, I could lie and say I had one of them or I could fess up and admit I got the two bushes mixed up and so my bushes scroll pumped oil into he dynamo drive compartment, it took a lot of miles until I noticed the oil leek at the back of the dynamo, the drive compartment was full, I was pleasantly  surprised that the (SRM) belt drive continued to drive in an oil bath.
There confession is good for the soul
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

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3370
  • Karma: 48
Re: bsa a10 timing cover
« Reply #4 on: 08.10. 2020 11:15 »
Hi Marvic,
Was the dynamo drive compartment.oily when you took off the cover?
When you moved the dynamo to fit the belt it probably moved away from the timing case?
I use a small clamp to hold the dynamo tight against the timing case while tightening the strap
The belt will run in oil, SRM recommend grease in there as it helps cool the belt

The cork washer behind the large pulley maybe missing, try pull -push on the pulley to see if there's end float
On my  SR there was no room for the washer but no oil enters the case

John
1961 Super Rocket
1963 RGS (ongoing)

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5263
  • Karma: 50
Re: bsa a10 timing cover
« Reply #5 on: 08.10. 2020 11:33 »
Bill,

My true confession is that I sloppily read your post as talking about the cork washer between dynamo and inner timing cover.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online Ratchet Richard

  • A's Best Friend
  • ***
  • Join Date: Aug 2020
  • Posts: 34
  • Karma: 0
Re: bsa a10 timing cover
« Reply #6 on: 08.10. 2020 11:56 »
Hi Marvic
My timing cover was leaking from the dynamo gasket ( the one between the actual dynamo and the inner timing case).  The bike was new to me and there is quite a long thread about it posted last month.  The solution was the wrong Idler bush with the scrolling the wrong way around.  Changed the bush and solved the leak. 
If you have not had a leak from Here before it could be that you have disturbed the cork gasket at the dynamo or behind the idler. 
What used to happen with my bike was that after I had but the timing outer cover back on I could ride the bike for about 20 miles before the oil started to leak.  It obviously took that amount of time for the dynamo compartment to file to the level of the gasket.

Offline marvic

  • A's Best Friend
  • ***
  • Join Date: Oct 2019
  • Posts: 30
  • Karma: 0
Re: bsa a10 timing cover
« Reply #7 on: 08.10. 2020 22:48 »
Yes I think mine is leaking from there too. No I never had leak from there before. What’s the idler bush? Sorry but I’m new to those type of bikes so still learning on them thanks

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5263
  • Karma: 50
Re: bsa a10 timing cover
« Reply #8 on: 08.10. 2020 23:21 »
Look at 67-686 in the exploded parts picture (click to enlarge), then, look at the photo. The spiral groove on the inside of the bush acts like a pump to send seeping oil back to the crankcase rather than into the outer timing cover. Some have been made with the spiral in the wrong direction, thus pumping the oil into the timing cover.

Richard L.

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Offline marvic

  • A's Best Friend
  • ***
  • Join Date: Oct 2019
  • Posts: 30
  • Karma: 0
Re: bsa a10 timing cover
« Reply #9 on: 09.10. 2020 05:39 »
Ok I see, but I haven’t touched that I just replaced the dyno srm belt unless it moved. But to check the bush I will have to remove the inner cover as well? Thanks

Offline Swarfcut

  • Wise & Enlightened
  • *
  • Join Date: Oct 2018
  • Posts: 1271
  • Karma: 19
Re: bsa a10 timing cover
« Reply #10 on: 09.10. 2020 08:28 »
 Just checked an original inner cover. The spiral groove is cut much closer than the bush pictured, at least 3 turns from the oil hole to the outer edge.

 The spiral runs anti clockwise in the same direction the shaft turns, just like a big "Left Hand Thread"  The bush pictured above has the spiral running the other way and is NOT CORRECT for the inner cover but is fine for the crankcase end of the idler shaft.

 Marvic. The small cork washer under the large domed dynamo drive gear is more of a simple way to eliminate end float on the shaft, rather than a true oilseal....that's what the spiral scroll does. Under normal circumstances a small amount of oil weep into the compartment would be expected, happily mixing with the grease lubricating the standard chain drive.

   If there is next to no float on the shaft you can assume the washer is in place. To inspect the bush the inner timing cover and dynamo drive gear have to be removed. The gear has a taper to fit the shaft and will  pull straight off, using a two legged puller.

 For now I would clean away the oil, reassemble and review again after a few miles running. The timing gears are marked with dots and dashes to ensure correct positioning on assembly as in normal automotive practice.  Plenty of hints here on the Forum achieving an oil leak free dynamo mounting, and as mentioned this very problem was recently discussed and simply solved.

 Swarfy.

Offline berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 1359
  • Karma: 7
  • keith.chesterfield uk 500sscafe.norbsa project
Re: bsa a10 timing cover
« Reply #11 on: 09.10. 2020 12:08 »
marvic can you be sure the gasket is sealing just above the oil pump and around the camshaft gear part of the casing

Offline marvic

  • A's Best Friend
  • ***
  • Join Date: Oct 2019
  • Posts: 30
  • Karma: 0
Re: bsa a10 timing cover
« Reply #12 on: 09.10. 2020 19:03 »
How can I be sure about that? I can’t see from outside once I install the timing cover. I will remove the cover tomorrow and see what’s going on

Offline marvic

  • A's Best Friend
  • ***
  • Join Date: Oct 2019
  • Posts: 30
  • Karma: 0
Re: bsa a10 timing cover
« Reply #13 on: 09.10. 2020 19:08 »
Chaterlea25 you’re right the dyno might off moved away from the timing case when I turned it a bit. I will check tomorrow thanks

Offline berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 1359
  • Karma: 7
  • keith.chesterfield uk 500sscafe.norbsa project
Re: bsa a10 timing cover
« Reply #14 on: 09.10. 2020 19:16 »
marvic you can inspect your gasket and see how well it has formed into the joint faces