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[Stevefromleicester]

SR1 magneto arrived yesterday.Good old ebay. Removed the impulse drive from the tapered drive end and trial fitted the metal timing pinion. Will need to cut a slot in it to accommodate the woodruff key or will it hold without ?
Made up three spacers of 1/8" plate to raise height of this platform magneto.Next job is to work out a way to fix it in position. I can shorten the original holding strap (which would have been for a MO1L magdyno) but it fouls the killswitch on the side of the magneto. Ive taken this bit of bendy metal off and fitted a piece of insulated wire so I can run that up to the handlebars to earth it via a switch. So far so good.
Tonights task is to gently file out a keyway on the timing pinion and start to line things up. I am desperate to put some fuel in and fire it up but not quite there yet !
Can someone tell me how to set up the valve timing . I presume the two dots on the pinions have to line up and is this at top dead centre ? Also when should the points inside the magneto open. Mine is a 1957 350cc Model G Deluxe.
I was thinking of 3/8" before TDC as a start. I have no advance/retard so maybe I should retard it a bit ?
I am aware that a spark when flicking the magneto over doesn't always equal a good spark when under compression but as I was removing the impulse part last night it flicked over a few times with a massive fat spark.
Also where do those shims on the timing pinions go ?
On the inside or ouside of the pinions or both ?
AS YOU CAN PROB TELL I HAVEN'T GOT A MANUAL YET
Any advice welcome.

[simon]

You do not want or need a woodruff key on you mag pinion. Otherwise you can't change the timing.

[zippy]

Hi,. For the valve timing, the 2 dots on the small crank pinion (Fixed in alighnment by it's woodruff key)should line up with the 2 dots on the exhaust cam pinion. Then fit the inlet cam pinion so the 2 single dots align. (one on each pinion. 1 will be on a tooth, the other between teeth. The 2 idlers just go in without alignment dots. They usually have a shim on each side. What you are looking for is all 4 gears at the same level with no detectable endloat with the cover fitted. each gear should be free to rotate.

[Norm]

As Simon says no key, the sprocket fits up tight on the taper. Does the mag have an auto advance sprocket or is it a single sprocket. If you have no manual advance on the mag it will need an advance fitted somehow.I don't know if an auto advance was made for the gear timing. I guess this all depends on if you plan on riding it or just restoring it

[Stevefromleicester]

Thanks for that info. I will clean up the small gear as its a bit oily and I couldn't see two dots on it maybe they are obscured by a fixing on the end its all a bit oily.
With regard to the keyway I can understand not cutting a keyway and I wasn't looking forward to doing it anyway.
I have made up a plate (1/8 mild steel) to screw into the three holes on the SR1 magneto and it will then fix to two bolts holding gearbox to chassis nearby, Ive filed the holes oval so I have a bit of adjustment.
I don't have the luxury of three corresponding holes in the timing case.
I am building this to ride green lanes in North wales it will get used.
The original strap will be cut down to give additional support as well.
Three pieces of 1/8 plate increase the height by 0.75 " which is almost the 10mm difference needed.(which is 0.39")
If necessary I will bolt some thin aluminium strip on as a final shim.

There is no advance/retard as someone on this forum said they had run one without and SR1's are a lot cheaper and available than MO1L's.etc.
If its no good without advance/retard I can always sell the SR1 and get a more suitable one.
I could also cut the outer timing case to create a removeable top section, fit an advance/retard on the end of magneto pinion then "Fashion" a suitable cover but that's in the future.
Some late nights in the garage but getting there and thank you again for your advice.
Stevefromleicester

[Norm]

Steve you will have to remove the worm nut so you can see the 2 dots. Left hand thread

[zippy]

Ha ha, nice 1 Norm, I've just come on to say exactly the same thing, but you beat me to it.

[Stevefromleicester]

Yes found the dots now and so valve timing done.
Now need to line up points on magneto to open at 3/8 before tic as no one has suggested any other setting for a 1957 model g yet. Surely I could fix the timing pinion on the taper on the magneto with a woodruff key as to alter timing I just lift off the pinion next to it, rotate magneto to correct position and refit pinion. If I do it by loose fitting the timing pinion on the taper without a key won't it move a little as I tighten it up ?
Hope to get this done and fire it up as I bought this basket case 6 weeks ago and want to test it out
(On private allotment road not on the highway before anyone comments)

[Norm]

Steve what is the gear you are fitting to the magneto" magneto has a taper? gear has a taper? if so, once tightened they won't move, adjustment by moving a tooth on the idler gears is not fine enough, you have to get it pretty close and 3/8" before TDC full advance is close enough, but if I remember you said that you have no advance/retard so if you set it at this mark you could do your leg an injury

[Mark M]

Steve, forget all this Woodruff key stuff. Use the taper as intended, it will give you the fine adjustment you need for this job. 3/8th before Top Dead Centre (TDC, not tic,) is a good start point for timing these engines and if you are lucky, may be bang on, pun intended! The compression ratio of the G engine is quite low so unless your timing is miles out any kickback should be relatively mild. If doing the timing job for the first time you need an assistant to get the gear locked onto the taper without moving the points at the same time, it is best to have someone on both ends as it were, to make sure neither component slips. You will get better with practice! And once you've done it check it again very carefully, it's a pain to have to remove the covers and re-time if it's wrong! REgards, Mark