What have you done with your bike/s today?

[Worty]

Too right Musky.  The top pic shows the counterweight jammed under the unit - rock solid.

Just thinking, I use 11/32" btdc on the timing (roughly 8mm, I think) but still get a bit of knocking.  I use 97-99 RON fuel topped up with lead replacement/octane booster which makes it about 98-100 I think??  Do you reckon I should change the timing to account for the fuel and reduce the knocking.  To be fair, it did run fine on 11/32" until getting to some long gradients when it'd start to complain.

You don't have a spare ATD do ya!!

Starting my third beer now - takes the pain away!!

[Swarfcut]

 Buy a lottery ticket while your good luck continues....

 For a start it happened in the comfort of your own home, not in the outside lane in the middle of a wet and windy winter night.

 Invest in an inner timing gasket, whizz off the inner cover and have a good look for debris around the timing gears and oilpump. With the cover off you can also clean out the breather cross drilling as suggested by bergs.

 Also see how well the holes in the rotating breather top hat bush line up with the hole in the casting. I have found variations where the hole is partially obscured by the position of the holes in the bush. As long as the camshaft and crank do not move, the inner cover can go back on without disturbing the idler gear/dynamo drive. If you are out of luck, then it's dynamo drive gear off, and align the timing marks by the book.

 Don't forget the cork washer under the dynamo gear, this eliminates float on the idler shaft. Goes without saying a good opportunity to clear all those blind holes and produce a perfect gasket seal.

 Route any breather extension pipe to become a chain oiler, aim to lower chain run. Outside on the top run will throw oil off the chain.

  Care with a Triumph ATD. Methinks they have different number of teeth, so not a straight swap.

  Swarfy.

[Worty]

Cheers Swarfy, sometimes it makes me wonder about how much more can go wrong.  At least, as you say, it happened in the garage and not out on a run.  Funnily enough, I completed a 160m run a few days ago and it didn't put a foot wrong.

What would your recommendations be on the timing question, by the way?

Fourth beer on way!!

[Greybeard]

I want to address the knocking I get occasionally.  Should I stick to 11/32?

I cannot help wondering if the broken ATD may have been playing up before it let loose and was causing your 'pinking', or that it was causing your timing to be inaccurate.

[Worty]

You're probably right GB, but just wanted to check to get the optimum performance out of the bike.

[muskrat]

G'day worty.
The golden rule in eliminating knocking (I call it pinging) is to retard the timing. BUT, the higher the octane the more advance it needs. Then there's the compression ratio to consider. A 10:1 motor would need to be retarded compared to a 7:1 motor.
I work on degrees btdc with a strobe on a degree wheel. I find the high 10.5:1 comp Cafe on 105 octane is best at 32-32 degrees and the lower 8:1 A7 on the same fuel likes 35. So it's all a bit of "suck and see".
Drop it back to 5/16" and see how it goes or don't labour up hills, throw her back a gear
Cheers

[groily]

I think Andrew does completely reconditioned units at £120, so I'm debating whether to buy one and be on the safe side.
RD, I like the sound of the Triumph unit, do you know the part number?

Part numbers:
Trihard 47502 A/B 50 teeth 15-18° movement
Beesa 47503 A /E 44 teeth 11-13° movement

BTH units were also used on '50s Trihards (5T, 6T with BTH mags), with clock-type spring and rollers. Same taper etc, and they'll go on Lucas mags if need be - with the change of pinion obviously.

[Colsbeeza]

Worty,
The specs for the Triumph and BSA ATD's attached. It seems probable that swapping the fibre gear from 50-tooth to 44-tooth is probable, and would give you the wider range of the Triumph ATD Groily has listed.
Can Groily or Cheeserbeezer confirm whether this can be done? Are the rivets pattern etc the same?
Col

[groily]

There are some possible issues.
The rivet patterns are the same but the rather more delicate Tri gear uses smaller diameter ones, is recessed one side to set the ATD deeper in towards the magneto (lack of space under timing cover, I think), and the centre bolts are consequently different lengths. Probably NOT a plan to enlarge the rivet holes given how thin the fibre 'hub' section is compared to the Beesa one. (Edit - If one were going BSA to Tri, that is, natch)
It isn't a completely straightforward swap to convert owing to the diameter of the recess not accepting the thick base washer for the BSA type ATD which anyway has holes too large for Trihard rivets. (Edit - which says some bits on the Tri unit are different). But with some work it could be done if need be. Easier to go the RD and Colsbeesa routes (see previous threads) to extend range of movement of the thing though, I think, if desired.
(And if using a BTH one, I think that would have to be slightly modded too, in the same areas, but haven't got one to look at and haven't tried.)
Why can nothing ever be straightforward!?

[Joolstacho]

Yes, looks like working with the beezer one is best. What.... 5 careful minutes with the Dremel? Too easy.

[Worty]

As always, thanks guys.  It may be beyond my capabilities to modify stuff like this and get it to work well.

[berger]

the BSA and trumpet gears are a lot different , i bought a mag that was advertised for A10 the ATD was trumpet gear.

[Billybream]

My bike packed up on a run, recovery needed to get me home.
After checking everything and even taking the head off, finally discovered the timing had slipped, 
never experienced that before, just thankful I actually found the cause and not corrected numerous issues. If was clear from the tapers that there had been movement. So the old girl has had a good decoke, vapor blasted head and gave the exhaust a good clean inside. Now the rebuild begins, annealing the rocker and head gaskets and grinding the valves and fitting the b__ pushrods.

[Worty]

the BSA and trumpet gears are a lot different , i bought a mag that was advertised for A10 the ATD was trumpet gear.

Was looking at an ATD on evilbay advertised as A7/10.  Messaged the fella as I counted 50 teeth.  He got back to me and said he'd counted 44 teeth.  Wrote back that I must be losing my mind as I saw 50.  He confirmed 44.  Was about to start taking the tablets when I thought I'd have one more go at getting to the bottom of the conundrum.  Turns out the first two photos were 50, and the third 44.  Looking even more closely, the 44 was a different unit.  Chap said the photos were of the actual unit????????????

[RDfella]

Whilst the GF is on the bench (replacing clutch pushrod) decided to replace the clutch plates with cork ones in an attempt to stop clutch slip. Ones in there were soaked in oil - not great for clutch plates designed to run dry. Haven't put oil in a primary (Villiers excepted) for 50 yrs due to clutch slip aggro back then, but here I am again with same issue. Trouble is, now I have an electric starter I need to have oil in there. If it slips after this, it'll be a plunger clutch going in there. Anyone got a spare dome?
Also whilst I'm at it, 3rd attempt at stopping n/s fork leg leaking. My spacers above the oil seals (recess in s/s holders was too deep for modern oil seals) helped enormously, but still had a weep. Now fitting rubber seals with a cone spacer locating the top bush.