Kicks like a mule.

[Bevel bob]

If i set my timing to give the best top end performance starting gets too exciting, backed off a few degrees and starting is no problem, so it seems that the advance and retard should have a wider range?.If i modify the unit to give more advance i should be able to retard the base setting and get the best of both worlds,any thoughts on how to do it?.

[DewCatTea-Bob]

" so it seems that the advance and retard should have a wider range?
any thoughts on how to do it?. "

____ It seems you've missed my posts on this subject !? _ If so, do a search of the word 'advancer', and you'll then find at least a couple related posts to check-out.
__ You didn't mention if your model uses the 18 or the 28 degree advancer-unit. _ I assume it must be the 18-degree unit, which does indeed cause the kind of situation you've brought-up.


Hopeful-Cheers,
-Bob

[Bevel bob]

No luck with the search, my AAU is of the type fitted to Mach 1 and already has a fairly wide range (about 30 degrees on a crank mounted disc). I have been adjusting my timing by tiny increases in points gap , a couple of thou makes a huge difference to performance and is easier to play with than timing discs.Next time you fit a disc check the variation in timing from a 12 thou gap to a 15, I think it will be a surprise.No wonder some go pointless.

[DewCatTea-Bob]

____ You could try taking the advancer-unit apart -(not as easy to do as it looks), and file-down the fly-weights (where they butt-up against their stops), so that they are then able to advance their cam a bit further.
Doing that should get you the extra added advance that you wish, while at-the-same-time only delay the full-advance RPM-point slightly past the stock/standard point, (such as 3200-RPM instead of the 3000, since those throw-weights would then be lightened slightly).
Then ya could have closer to the Mk3's max-advance while also keeping the M1's stock static -timing.


" No luck with the search, "

____ That's strange... cuz when I enter "advancer" into the search-box (at upper-right of page), several postings with that word, can then be found !
Oh well, they may not have much of interest to you anyhow, since you have the wider-range advancer/AAU.


" a couple of thou makes a huge difference "

____ How true... the point-gap's actual size can indeed vary the ign.timing significantly !


Dukaddy-DUKEs,
DCT-Bob

[MotoMike]

increasing the gap would advance you spark, wouldn't it? Owed to that causing the points to break sooner.

[Bevel bob]

Yes, it can be a bit confusing but increasing the gap means that the fibre heel sits closer to the cam and strikes it earlier thus advancing the ignition.As the gap can be usually 12 to 15 thou if the motor was timed with a 12 thou gap and later reset with say 14 thou you will find a considerable increase in the timing, I did measure it once and was shocked by the increase(can't remember now how much!) but enough to be far too much!, so if you must play with it,ensure that you only work with the first part of the cam(it does vary) and only increase or decrease the gap by one thou, check the gap before you start (a light dragging fit) and then check ease of starting and performance, you can easily go back to where it was if its worse. WARNING too much advance can damage your motor! overheat/sieze burn piston etc. I check that the combustion is good by the position of the corona line on the spark plug outer electrode,somewhere in the middle seems to be best on the 250 although the ultimate is supposed to be closer to the bend( you need to research this, get your eye in and work with a clean plug of the right grade and at at least 5-6k revs on a fully warmed up motor over a mile or so) for the line to be seen easily. You also need to be a bit of a petrol head nut case as well.Which we all are --right??.