Carb' Issue - ATD's - Ignition timing

Chris Launders

Well Known and Active Forum User
VOC Member
I had the same with petrol in France 20 years ago, but not in Belgium Holland or Germany, I had a chopper with a very small tank , so I had to fill it to the top every 40-50 miles and some always spilt out as the cap didn't seal very well and access was a bit restricted by the bars, the French stuff just disolved the paint.
Chris.
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
, I am about to try 34 degrees of advance with 6 degrees retarded. I can already tell you with 6 degrees retarded there are no starting issues.
Set, then after a 5 mile run remeasured - just to be sure - the ignition timing to 34 degrees BTDC fully advanced. Went for a 220 mile day run and found that during the day my GPS logger (HOLUX GPSport) indicated I had reached a max speed of 128 kph at some point during the ride. Now I was not out to set any speed records nor did I attempt a max speed run.

In comparison, a run over the same route about 3 weeks back, when the timing was actually 28 BTDC, had a GPS recorded top speed of 112 kph and again, on this run I was not out to set any speed records nor did I attempt a max speed run.

I know its not scientific - but - it seems that there is better performance from my Comet with full advance at 34 BTDC, compared to 28 BTDC.

Martyn
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
I bought a Roy Price ATD. Does it have the standard advance range, or a reduced one?
My Roy Price ATD had the standard range i.e. 34 degrees of total advance. It was this ATD that had the pivot pin failure. As part of the repair I added weld metal to the ears, so reducing the total range to 28 degrees.

M
 

nkt267

Well Known and Active Forum User
VOC Member
I am waiting for a new ATD to arrive ,It is going into production soon I am led to believe. It will have 15 degs of advance I am told,,ie 4 degrees at full retard and 34 at full advance..John
 

b'knighted

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VOC Member
My Roy Price ATD had the standard range i.e. 34 degrees of total advance. It was this ATD that had the pivot pin failure. As part of the repair I added weld metal to the ears, so reducing the total range to 28 degrees. M

A section member has been feeling displeased with the performance of his Comet since recently having his timing reset by a local engineer/mechanic. I'd assume that he was dissatisfied before it was reset.
Prior to retiming it ourselves we checked the current settings.
So far as I could tell it was 4 degrees BTDC on full retard but about 46 degrees BTDC on full advance. This is with a relatively new, heavy duty ATD - presumably one of Roy Prices. The bike starts very well so re-adjusting to give correct timing at full advance would seem unwise as starting will become impossible.
Is this increased range indicative of pivot pin failure?
 

vibrac

Well Known and Active Forum User
VOC Member
First question is the 'Heavy Duty' description fits the new ATD being produced by Barry Walters or perhaps Dave Lindsley not Roy Price. Also I see above somebody said they bought a Roy Price ATD the inference being recently,I doubt recently, I am afraid Roy died over a year ago now and its perhaps two since any were produced attributable to him. In addition I do remember him saying just before he died that he had been reducing the 'throw' of his ATD ( To some figure around 17 degrees or less (34 degrees engine)I think)
 
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