Timing side oil leak

[metalflake11]

I've bumped the dynamo belt thread for you to look at and make your own mind up what to do.

[bsa-bill]

I seem to recall a while ago somebody reported that they had discovered that the idle gear bush had been scrolled incorrectly

That could well have been me, the two bushes for the idler pinion are scrolled in such a way as to throw any oil in the bushes  inwards from both sides towards the idler gear, and the scrolls are very effective, I had the wrong bush on the inner cover so oil was thrown out towards the dynamo sprocket and into the dynamo chamber, it did not stop the dynamo (belt drive) but eventually filled the chamber and leaked out behind the dynamo

[Greybeard]

Would somebody please confirm my note that the dynamo belt should be tightened until it can just be twisted to 90° at mid span.

Later:
Ah, I see that MF does his to less than 90° but more than 45°

[Swarfcut]

 Bill,   BSA  certainly added to the partsman's confusion with those bush part numbers. Three of the same bush, 67 0686 support the camshaft.

 The idler bushes are different conundrum. The same bush 67 0686 is in the crankcase, 67 0286 is the one in the inner cover, shown in early parts books. The later parts book shows them reversed.  A later inner cover on an earlier engine could be the problem if the scroll is found to be working the wrong way and the engine has two identical scrolls rather than a pair of mirror image scrolls in the idler bushes. Of course it could be a typo......or the bush in question has the scroll incorrectly machined.

  Richard.. The small cork or felt washer 67 0708 under the dynamo drive gear  is described as an oilseal, but as noted is a cheap and effective way of controlling endfloat. Assemble with a dab of grease to prevent friction burn on dry start up.  Original timing cover screws are 1/4 Whit slot head. Be careful if using hex heads, threads pull easily.

 Swarfy


 

[muskrat]

G'day Ratchet.
Just blew up your photo and noticed something. Is that a hole that shouldn't be there? Red arrow in attached pic.
Cheers

[chaterlea25]

Hi All
Here is another thread that this morning seemed to be heading in the wrong direction with its advice
Wrong bushes and so on
BUT
Happily it seems to have recovered,   

The Obvious is almost always the solution
Well spotted Musky 

I use some non setting Hylomar on the dynamo cork, A small G clamp can be used to hold the dynamo against the inner timing cover to both help seal the dynamo and prevent it from rotating while tightening the dynamo strap
I have fitted a few belt kits, I aim for 90 deg twist, but the belt must not be able to touch the screw boss between the belt runs that is often eaten by the original chain
Push /pull on the large dynamo pulley to see if it moves in out, (an easy way to check if there is a cork washer behind it)

John

[Ratchet Richard]

You are quite right Muskrat, there is a hole where you indicate. It goes through to the outside, half is covered by the cork dynamo washer and the other half is open.  Chaterlea, thanks for reminding me that these forums can go way to deep and very quickly. 
The hole Muskrat pointed out could well be the source of the oil leak, as when I started the bike up from cold there was no leak and even after about five miles there was still no leak. However after about twenty miles when I got home there was quite a leak going on. The leak stops as soon as the engine stops.  So it may be that it took some time for the dynamo compartment to file to the level of Muskrats hole before leaking out. 
My conundrum now is Two fold, 1/ why is there a hole 2/ why is oil getting into the dynamo compartment as I thought someone said it should be dry in there.
This sort of takes me back to the idler gear bush! 
This might be a good to time to let the forum know why my nick name is ratchet, it is not because I am any sort of machanic, quite the opposite actually.  I had bought a new pro socket set from Halfords And was going to take it back because the sockets would not come off the square drives, I mentioned this problem on a Harley-Davidson forum that I was a member of and was promptly hold that I needed to push the button on the top of the drive to release the socket, from that point onwards my nick an was ratchet Richard.
In my defence the last socket set a bought before the Halford one was in 1977 and they didn’t have lock buttons on sockets. 
So please be patient with me as I have to do a lot of research to find out what all the terminology refers to like idea gear bush scrolls.
Really enjoying the challenge though. 
Thanks again for all the input.

[Swarfcut]

   One of my covers came with a hole like that, coinciding with the end of the small threaded bar that holds the dynamo strap. Someone's idea for replacing the strap without major dismantling?

   I'd be inclined to block the  hole with silicone and give it a try.  If the belt cavity continues to fill with oil the source can only be the inner timing cover bush/spindle/seal.

 Swarfy.

[muskrat]

G'day Ratchet.
That's good we may have found the leak but now the fun bit!
Obviously the inner cover will have to come off. You could plug the hole in situ but that doesn't address the oil getting in there. The shaft, bush and seal need inspection. So if the dynamo drive sprocket removal gives you grief remove the inner cover with the sprocket/shaft/idler gear as one unit. You'll need to re-time it anyway.
WARNING: if you take it out as a unit, DON'T turn the motor over without replacing the idler back with the timing marks lined up.
Cheers
PS: Swarfy got in first. Try that first

[bsa-bill]

The later parts book shows them reversed.

thanks swarfy - knew it couldn't be my fault

[Greybeard]

WARNING: if you take it out as a unit, DON'T turn the motor over without replacing the idler back with the timing marks lined up.

This is because the camshaft is no longer timed to the pistons, so you run the risk of a piston and an open valve colliding. You don't want that! 

[shabashow]

I had a hole similar to that pointed out by Muskie in my timing case. I can only assume it was drilled to allow oil into what should be a grease filled sealed section, as it too leaked copious amounts of oil when I built the bike up. It soon got sealed off and no more oil leaks, from that section of the engine anyway. It's amazing what previous owners did to these bikes over the years, yet they still ran.
 

[bsa-bill]

Could that hole have been drilled to get access to the pin that holds the dynamo fixing strap without taking off the inner case ??

[shabashow]

Don't think so, my hole lead into the inner timing chest, hence the oil leaks.

[Ratchet Richard]

Thanks again for all the helpful input.  The hole in my case goes out of the inner case into Fresh air any oil building up in the dynamo drive space will run out down the right side front of engine.  Chaterlea25 suggested push pulling the dynamo pulley which I have now tried, there is definitely some in out movement, enough for it to make a small knock sound. Not being an engineer I would not like to guess on how much movement. 
My next plan is to take the dynamo pulley off and check if there is an oil seal on the idler pinion (67-0708). I expect I will need to take the inner cover off to see if oil seal is there. 
I have got the engine at TDC on right hand cylinder and I will be very careful not to pull the idler gear out.  I don’t really want to just block the hole up as there really should not be any oil in there in the first place.  I am waiting for some spares to come from Draganfly before I get stuck in.