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How to set ignition timing - B31 #21077
02/08/07 12:11 am
02/08/07 12:11 am
Joined: Feb 2007
Posts: 6
Jondaryan Qld Australia
G
guzzi126 Offline OP
BritBike Forum
guzzi126  Offline OP
BritBike Forum
G
Joined: Feb 2007
Posts: 6
Jondaryan Qld Australia
Hi all,
the cable for the magneto advance control on my B31 has broken, and to remove the remains I had to remove the maggy. How do I set the timing, the procedure in the workshop sheets seems a bit hit and miss, and I don't have anything to measure the piston height from TDC.
any clues folks
cheers

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Re: How to set ignition timing - B31 #21078
02/08/07 12:56 am
02/08/07 12:56 am
Joined: Feb 2002
Posts: 246
Ohio, U.S.A.
GOLD S-TARvin R.I.P. Offline
In Remembrance
GOLD S-TARvin R.I.P.  Offline
In Remembrance
Joined: Feb 2002
Posts: 246
Ohio, U.S.A.
Hi guzzi126,
Probably need to make a bumpstop out of an old spark plug and use a degree wheel on your crank to determine acurrate TDC. Start out by reading : this old thread and ask away again.

May be a trick to to tightening down the magdyno driving pinion as it tends to move things a little
when fully home. Thats why its good to have the degree wheel mounted as this may be a hit and miss session till you get it right where you want it.
bigt


GOLD S-TARvin
OVBSAOC # 1625
1960 DBD34 Gold Star
1956 DB34 Gold Star
1969 Bonneville
several basket case Triumphs
Re: How to set ignition timing - B31 #21079
02/08/07 3:40 am
02/08/07 3:40 am
Joined: Jan 2006
Posts: 149
Oslo
R
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Joined: Jan 2006
Posts: 149
Oslo
Dunno if this is the most political correct way to do it but here`s what I do on my bikes. Never done it on a B31 though so dunno if it`s possible on that one.

With my smallest screwdriver down the plughole I put the engine in fourth gear and turn the engine by the rear wheel.
When the tdc is found I mark the screwdriver. I then take it out and measure my self up to the right position, then set a new mark at where my piston should be. You can mark the screwdriver with some electro-tape. Note that the screwdriver has to be as vertical as possible to obtain a good result. Remember to turn the rear wheel forward while doing this to take up the backlash in gears etc. But of course the spark is to come before tdc (in case I was unclear).

Probably som hit and miss by doing it this way but I gets my butt home.


1940 M21
1960 Golden Flash

"Everything takes longer time than it takes"
Re: How to set ignition timing - B31 #21080
02/08/07 12:06 pm
02/08/07 12:06 pm
Joined: May 2004
Posts: 3,820
Sydney Australia
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BSA_WM20 Offline
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Joined: May 2004
Posts: 3,820
Sydney Australia
As the mag is currently out of the bike measure the points gap very carefully and put a little nick in the body opposite the widest gap position of the rotor, this will save you much time latter when trying to do this in situ.
Lube the cam ring & follower then set your points to .012" & put the maggy back in the bike without the timming gear.
Now the fun, being that it is a B33 and you now have the timming cover off you can turn the crank with an open ended spannar or a slightly oversized socket that will fit over the nut & lock washer.
Put a wooden skewer down the plug hole and rotate the crank to find TDC. Rest a razor blade, on the head so that it comes into contact with the skewer then rotate the skewer to make a grove . Pull out the skewer and make another grove above the first one at whatever the piston advance should be for your year B33.
Put the skewer back in the plug hole and the razoe back on the head then rotate the motor till the second mark aligns with the razor blade on the compression stroke ( both valves closed).
With the cam ring set to full advance stick the fag paper in your maggy points and rotate it till you can just slip it out.
Now for the tricky bit slip the drive gear over the maggy and give it a light tap to hold it on the tapper, wedge somthing flat ( not a screwdriver blade ) in between the idler & the drive gear and tighten the nut on the end of the maggy.
Check the skewer, if the mark still lighns up with the razor blade then congratulations, if not start from the fag paper again.
Keep the skewer in your kit just in case you have to do it by the side of the road.
Because the points are on the left & the plug hole is on the right I find that if I lightly rest the razor blade against the skewer I can feel the the blade "drop" into the timming mark so you can do it from the left side by feel rotating the rear wheel with your foot.


Bike Beesa
Trevor
Re: How to set ignition timing - B31 #21081
02/08/07 1:33 pm
02/08/07 1:33 pm
Joined: Feb 2007
Posts: 6
Jondaryan Qld Australia
G
guzzi126 Offline OP
BritBike Forum
guzzi126  Offline OP
BritBike Forum
G
Joined: Feb 2007
Posts: 6
Jondaryan Qld Australia
Thanks folks for your collected wisdom, now in hindsight I could have removed the remains of the cable without touching anything else, and made a lot less work for myself, but the light in the shed isn't so good, the sidecar was in the way, and this way I learnt something as well
cheers
Thommo


Moderated by  Allan Gill, Jon W. Whitley 


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