Author Topic: Setting ignition timing with timing disc  (Read 3936 times)

Offline isuzu

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Setting ignition timing with timing disc
« on: 16.08. 2012 14:09 »
Hi All,
I would like to check the timing of my 1956 A7 (manual retarding and an automatic advance).

I read that poking around in the plugholes with a stick or something to check piston height does not give a serious result. So I have a timing disc now and would like to know where to put it on ...

Should it be on the automatic advance, the points or the drive side of the crank?

groetjesDick

Offline Tukig

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Re: Setting ignition timing with timing disc
« Reply #1 on: 16.08. 2012 16:34 »
Hi, I attached mine, one of the plastic ones, to the cush drive nut using some magnets salvaged from a computer hard drive. These are incredibly powerful for their size. Fashioned a pointer from aluminium sheet (wire wobbles too much) and found TDC through the plug hole. Seemed to work fine (until big end failure stopped play!)

Offline ian davies

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Re: Setting ignition timing with timing disc
« Reply #2 on: 16.08. 2012 21:27 »
Hi. I bought a timing tool from SRM, screws into the plughole cost a fiver, works well, my A7 runs and starts perfectly. Cheers Ian.
ian davies

Online bsa-bill

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Re: Setting ignition timing with timing disc
« Reply #3 on: 16.08. 2012 22:06 »
The cushdrive nut from SRM has two nice little threaded holes, handy for fixing a dial to
All the best - Bill
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Offline duTch

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Re: Setting ignition timing with timing disc
« Reply #4 on: 17.08. 2012 09:42 »
Dunno if it's coincidence, but I found that the split pin holes on the 2 cranks I have are at 90˚ to tdc/bdc for a pointer (SS welding filler rod), but you still need a static reference point..but easy to work out, and you only need do it once!
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
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Offline Topdad

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Re: Setting ignition timing with timing disc
« Reply #5 on: 17.08. 2012 11:57 »
Hi Isuzu, sorry to sound a slightly non high tech note and all the previous ideas are more than worth taking on board but I still stick "things" down my plug hole and still use a fag paper in the points as I did in 1966 when I got my 1st a10 , worked then works now and my pride an joy starts 1st/2nd kick even after being left for over 6 mths . I'd get these thingy's to set things up and then try the old method ,as if it ever stopped on a ride how likely is it that you'd have a timing disc with you and a strobe to check things but you would normally be able to find  a pencil ,a fag paper and tools required to open the timing side .
Sorry I've just reread the above and sounds like i could be accused of being stuck in a time warp I'm not (also please don't take " sticking things down my plug hole " out of the context of this post or I could be locked up or worse 'cause a few Aussie members to spill there beer !) nor am I against progress it's just that I work on the premice of if a process works why change it. Also I've assumed you have a magneto if not the case please file all of the above in bin ,best of luck BobH   
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Offline ian davies

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Re: Setting ignition timing with timing disc
« Reply #6 on: 17.08. 2012 13:08 »
I fully agree with Topdad.
ian davies

Offline Goldy

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Re: Setting ignition timing with timing disc
« Reply #7 on: 17.08. 2012 21:14 »
I also agree with you topdad. I use a piece of welding rod and a piece of tissue paper, as I don't smoke anymore.
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Re: Setting ignition timing with timing disc
« Reply #8 on: 17.08. 2012 21:58 »
 Bugga Bob, coffee all over the screen. *smile*
As per picture, alloy disc marked in 5 degrees behind nut, pointer att behind chain adjuster (or two inner primary screws for s/a). Use dial gauge down plug hole to find tdc and mark disc. Rotate crank to desired advance (30-35 degrees) and adjust timing.
I also made a timing plug so I don't have to use the disc. Take an old spark plug and knock out the center. Thread hole 3/8" and screw in a screw/bolt/stud/threaded rod. With piston at desired height screw in plug and then screw in threaded rod till it touches piston. Use loctite on thread before inserting so it stays there (rod not plug). Now when you want to do timing it's just screw in the plug and bring the piston up to it.
 I have a few at different lengths for different motors or timing.
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Offline Rocket Racer

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Re: Setting ignition timing with timing disc
« Reply #9 on: 21.08. 2012 08:49 »
I used to use blu tack to hold a degree wheel on my crankshaft end nut and using one of the engine case threads attach a bit of bent wire as a pointer.
These days (the degree wheel fell to bits) I typically find a piece of marked rod quite satisfactory held vertically in the spark plug hole. I also have a screw in the spark plug hole depth rod thingy marked in mm, but given the spark plug holes are not horizontal, measuring in at an angle you'd theoretically need the depth gauge to fall an additional 1 or 2 mm to compensate the angle of the hole. Mind you doesnt seem to make much difference if I do that or not.
A rod with a tdc notch and a notch for timing at full adv, does it for me.

Then of course there's checking the timing on both cylinders and averaging any bias between the ignition.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline isuzu

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Re: Setting ignition timing with timing disc
« Reply #10 on: 21.08. 2012 11:28 »
Thanks for the tips supplied guys.
Reason why I wanted to check my ignition was the fact that the engine did not pick up nice from stationary to a bit more rpm (like when driving away) this gave a little hickup. More rpm gives no problem.
Thought it was a pilot screw problem but turning the screw did not make things better. Checking the igition with a long tooth pick like piece of wood in the plug hole showed a good ignition point. So would I need a new carb then?  (=276 now). I checked the magneto pickups to clean the pick ring; 1 of the brushes was stuck in it's holder and the brush was coming out after some fiddling and wd40. Seems now that it has solved the problem!
I have more rpm stationary and the pilot screw could be adjusted so there is a good tickover and 4 takt sound now.

I'll fix me a plug like on the pics

Offline Topdad

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Re: Setting ignition timing with timing disc
« Reply #11 on: 21.08. 2012 14:29 »
isuzu, Glad you've sorted the problem. Musky , 'bout the coffee ,sorry,  screen cleaners in post and will try to keep future posts clean ,BTW haven't you posted that timing/plug idea before? this time i'm going to make for myself ,there see def not stuck in a time warp bet i still use it with a new pencil, regards Bob
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Re: Setting ignition timing with timing disc
« Reply #12 on: 21.08. 2012 20:14 »
 G'day Bob, got racing tear off's on the screen now. *eek*. The timing disk and pointer are permanently mounted on all 3 of my BSA's as all have got lektrick ign. About the only time I use the plugs these days is to check TDC position on the disc. Plug in turn motor till touch, mark disc, turn backwards till touch, mark disc. TDC is 1/2 way between marks.
Cheers
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Offline Topdad

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Re: Setting ignition timing with timing disc
« Reply #13 on: 22.08. 2012 16:55 »
Musky, wonderful way of doing things ,after say, timing as always been a do and forget thing with me , spend a fair bit of time getting right but once done never worry about it ,I'm not riding her as much or as regularly as you  (  thats another tearaway used )  so i don't need to be as careful as you also I suspect you motor far quicker than I do these days, best wishes BobH.
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