Ignition Timing Confirmation

[bikerbob]

I am fitting a refurbished magneto to my 1956 S/A A7. The book  gives the setting as 5/16" BTDC does that equate to 35 degrees, also rather than remove the primary case to fit a timing disc I have riigged one up to fit onto the drive side of the crankshaft. I have done this by tiurning an aluminum boss that fits the disc and also fits into the small hole on the end of the crankshaft this hole is about 1/4" dia and about 3/8" deep the boss is a tap in fit to the crankshaft. I have modified the disc so it clears the oil pump and the idler pinion nut, I presume this mod will make no difference to actual timing ie fitted to the timing side rather than the primary side. Thankyou.

[muskrat]

G'day Bob.
With no solid fixing the disc could move. Check your marks every time.
With the fuel (not the old petrol) these days you may need to retard the timing. Richard (Orabanda) did tests and found 32 was better. Depends on the fuel you use.
A few posts to look at
https://www.a7a10.net/forum/index.php?topic=851.msg5519#msg5519
https://www.a7a10.net/forum/index.php?topic=3122.msg21340#msg21340
https://www.a7a10.net/forum/index.php?topic=3831.msg26667#msg26667
Cheers

[bikerbob]

Thanks for the reply I have checked that the disc is not moving having set the timing at 35 degrees 3 times and nothing has moved so just want to be sure that I set the correct degrees before finally setting the magneto. I had previously set it to 5/16" and it did give an occaisional kick back so maybe a couple of degrees retard maybe better.

[Swarfcut]

 Well that confused me!
  Drive side is where the clutch is, your clever timing disc is on the oilpump /timing gear side. Don't forget to adjust the points first, and set up at full advance. Manual maggy to full advance or wedge ATD unit fully open. The book settings were for the fuels of long ago, so expect some further minor adjustment for the best running, to echo Musky. Also make sure the points break  on the compression stoke, before top dead centre. A few folks get it timed up over the hill, piston going down. Wrong!!

 Swarfy.

[bikerbob]

Thanks for that swarfcut my mistake should have said timing side. I have set timing numerous times on different bikes but usually by rods down the plug hole it is just that when setting by degrees different people have different ideas as to what is the correct setting. If you take my other bike which is a 1963 A65 the manual says 37 degrees but when I fitted Pazon electronic ignition they say 34 degrees but I was told SRM say 32 degrees. I did contact Pazon at the time and the answer I got was well try both and pick whichever you think is best I eventually settled for the manual 37degrees and the bike starts and runs great.

[RichardL]

I guess I'm confused. In the case of the disk on the timing side, is the timing done with a timing light and the engine running, a fag paper in the points, or a points-opening detector circuit?

Richard L

[RDfella]

All three if you like, Richard. But not at the same time!

[bikerbob]

High Richard have been having magneto problems and have purchased a fully refurbished magneto with a 3 year warranty When I removed the timing case I noticed that there was a small hole in the end of the crankshaft I think it used for balancing the crankshaft. So I thought maybe I could use that for fitting a timing disc rather than removing the primary case to fit one to the cush drive. the hole is quite small only about 1/4" dia and about 3/8" deep. I made an aluminium boss that was a tap in fit into that hole and takes a modified timing disc basically a normal timing disc cut to suit and bent to miss the oil pump and the idler pinion nut. It works, as I have said before I have tried it out 3 times without any movement so for me it saves removing the primary case all I am trying to find out now is what degrees to set it at 35degrees is 5/16"which is the factory setting for an A7 but because of modern fuels some are saying I should retard the ignition maybe couple of degrees but others on the internet are saying this only applies for high compression engines and there are some who say you should advance the ignition. Previously it was set with a rod down the plug hole to 5/16" BTDC and the bike started and ran Ok for a number of years but did sometimes rarely kick back so I am now minded to take musky's advice and retard the ignition maybe a couple of degrees. I am tied up tomorrow so cannot get back to work on the bike until Tuesday so will attempt take a photo and post it here.

[muskrat]

G'day Bob.
The most accurate way to time it is with a strobe light. That way you can see the advance mechanism working. Trouble with doing it timing side is being covered in oil!
I have timing discs on the primary side under the cush nut. The Cafe has open rimary so easy to check. The plunger gets checked once a year if she needs it or not. Not a big deal to drop the cover off.
Another one of Orabanda's upgrades is to slot the three mag holes to be able to adjust the timing without touching the drive pinion and done with the motor running.
Higher octane burns slower so timing i advanced, higher compression burs quicker so timing is retarded. My A7 with 8:1 and on 98 is set at 35 degrees. My Cafe with 10.5:1 and on 105 octane runs the same 35 degrees.
Cheers

[RichardL]

Bob,

I apolgize if my ilstated question caused you extra typing. My confusion is in regards to if you are using your disk arrangment with the engine running and a timing light, or just to confirm the static recognition of open points. I can't recall ever running my engine with the timing cover off, so not sure how much oil spill is involved.

Richard L.

Yessiree! Muskrat was just ahead of me with the oil concern.

[bikerbob]

All this modern thinking is getting me confused I am 80 next week I have been riding motorcycles different makes since I was 16, back then in the 1950's and 60's nobody ever used a timing disc or a strobe light everything was done down the plug hole. I have watched motorcycle mechanics doing timing on various bikes and they never used timing discs or strobe lights. I can see the advantages of using these things but are they really needed on a bog standard A7 that now only does a few hundred miles a year in fine weather never going above 60mph after all it is not a high performance machine or a race bike. So I think I will now set the Ignition timing using the timing disc  at the book setting of 5/16" 35 degrees and see how it goes after all it has run at that setting  since I bought the bike in 2014 without any problems until the magneto failed. The internet is a good thing but it can give you too much information to think about. I will post photos of my setup on the timing side tomorrow for anyone who is interested.

[berger]

bikerbob i like the way you think regarding things getting into depth etc. yesterday when showing my mate andy the berger build so far with balanced crank and VAST expense on parts he said " just think in the 70's we hit them with hammers shoved grass in flat tyres and got up to all sorts of tricks just to get out on them

[bikerbob]

Got back a bit early today so nipped in the garage took a couple of photos gives you an idea of my setup.

[muskrat]

G'day Bob.
I can see the "method in your madness". How do you find TDC accurately? A dial indicator down the plug hole?
I use a piston stop plug down the hole. Turn crank till piston touches and mark the dial, then turn back the other way till piston touches and mark the dial. Mid distance between the marks is TDC.
Easy to make a piston stop by knocking the guts (porcelain) out of a spark plug then tapping a 3/8 thread in it, then screw a bolt into it. Once you find 35 degrees put it back in and screw the bolt down till it just touches the piston. Lock the bolt in that position. From then on you won't need the disc, just screw in the piston stop.
Cheers

[KiwiGF]

Ref use of timing discs etc, it is surprising how accurately you can get the timing by the “measuring down the spark hole” method, just a small rotation of the crank results in obvious change of the depth before TDC.

On a flat top piston GF with 356 cam I have not found it is necessary to get the timing spot on, albeit mine is (now) set by a strobe and is electronic (BTH mag) which is a “do once” setup.