Author Topic: HT Leads etc  (Read 1608 times)

Offline Oscarmark

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HT Leads etc
« on: 08.06. 2013 19:36 »
Stupid question time... just about ready to start the bike...new carb, reconditioned mag, new wiring loom... which lead from the mag goes to which cylinder? Also is there any way to set to timing without a gauge?

Cheers
Mark

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Re: HT Leads etc
« Reply #1 on: 08.06. 2013 19:54 »
Hi Mark

Usual practise is to run the lower mag pick up to the left pot.

For timing I usually use a piece of welding rod down the plug hole as vertical as you can get it and file a TDC mark on it and then file a mark at whatever advance you want a bit lower down. Can be easier if you strap a piece of wood or metal across the head above the plug hole to give a datum. 

Jim
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Offline a10gf

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Re: HT Leads etc
« Reply #3 on: 09.06. 2013 14:46 »
If you put new plug caps on use NON RESISTOR type or you could do damage to the mag'. They are not expensive at all.
Regards colin

Offline Oscarmark

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Re: HT Leads etc
« Reply #4 on: 09.06. 2013 16:30 »
Thanks guys,

The leads and plug caps were supplied fitted by the chap who re-built the mag, so they are the non-resistor type.
Going to try and set the timing now... will let you know how I get on.

cheers

Mark

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Re: HT Leads etc
« Reply #5 on: 09.06. 2013 17:34 »
Hi Mark
Not sure what bike you have but timing needs set at full advance so sports types with handlebar adjustment set the lever to advance,
We lesser beings with auto advance units need to jam them in full advance position, a little wedge of wood or a nut does the job to keep the bob weights out against the little springs (if using a nut tie a bit of string through it so it can't disappear)
All the best - Bill
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Offline Oscarmark

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Re: HT Leads etc
« Reply #6 on: 09.06. 2013 19:23 »
My bike is a 54 A10 with a 57 Road Rocket engine. I have manual advance / retard on the handlebars... books say 3/8" BTDC. I have tried putting an old clutch push rod into the right hand spark plug hole, but it is difficult to get it to TDC as if you go too far of course the piston descends!! Also, how do I know if it is on the compression stroke?? This is all very new to me... I can hardly wait to fire it up..

Thanks again.

Mark

Offline a10gf

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Re: HT Leads etc
« Reply #7 on: 09.06. 2013 20:15 »

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Online bsa-bill

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Re: HT Leads etc
« Reply #8 on: 09.06. 2013 22:12 »
Quote
how do I know if it is on the compression stroke??

You need to remove the rocker covers and see on which cylinder both Rockers have play ( valves closed, tappets have some free movement) this is the cylinder on the compression stroke.
It is simply to get the leads  in the order you prefer, it matters not a lot as both cylinders travel up and down together, if you time the wrong one simply swap the leads.
All the best - Bill
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Re: HT Leads etc
« Reply #9 on: 09.06. 2013 22:50 »

Also, how do I know if it is on the compression stroke??

Mark

With both spark plugs out, bike on centre stand, in top gear, turn the rear wheel with one hand while you have a finger in a plug hole, or a screwed up tissue. When that cylinder is on its compression stroke you'll get a sharp blow through the plug hole.

Online Billybream

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Re: HT Leads etc
« Reply #10 on: 10.06. 2013 08:30 »
Hi Mark.
Best to read the manual regarding ignition timing, but be prepared to remove the timing cover, so you will need a new gasket, or some form of gasket sealant, as magneto pinion has to be released, an extractor is required also, so just an heads up to have equipment and parts to hand.
I use an old sparking plug, drill the centre out and use suitable rod with TDC and timing dimension marked, you will get better control of piston position via rear wheel.
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Re: HT Leads etc
« Reply #11 on: 10.06. 2013 08:58 »
Remove both plugs. Loosen ATD (or timing wheel) on magneto armature shaft. If you have a manual magneto make sure the mag cable is slack and the cam ring is returned to its stop in the cam ring housing. On automatic mags wedge the ATD weights open. Engage top gear. Rotate the back wheel forwards whilst holding thumb over a plug hole to find compression, then on the same cylinder, continue to rotate the wheel forwards to find TDC on the compression stroke then rotate the wheel back to the required btdc setting. Rotate the points / magneto armature shaft clockwise until the points are at their breaking point, then tap the ATD or timing gear onto the mag armature shaft. Tighten the ATD or fixed gear, remove ATD wedges. Connect plug leads so that the pickup nearest to the heel of the points connects to the firing cylinder i.e. under compression. Start the bike! If the exhausts get very hot very quickly and power seems poor you may have your timing a bit too retarded. If you get kickbacks, or pinking when riding, even with the mag cable tightened slightly you may be over advanced. If you have a manual advance / retard you may find the bike easier to start by pulling the adv/ret cable about 1/2 - 2/3 of its travel, not all the way, this will probably weaken the spark too much.
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