DTI GYT internal rotor points gap

[cloggy]

 Just returned from about as far in the North of England as one can go; having done an excellent Vinduro near Wooler Northumberland. I was on my MK4 DMS TT500 and Simon rode his Champion framed DT1/2MX Special. He and it had an excellent first day but it wouldn't run well the second, and anyway he crashed and blew the Husky forks oil seal turning it  into a pogo stick.
 We got it running fine today by gapping the points to 8 thou", but what's the Yamaha setting? Any more than 8 and it wouldn't even spark.

[sleepy]

My recollection of the DT1 was that the GYT kit used the stock external rotor ignition but the timing was reset to around 2.4mm BTDC compared to the stock 3.2mm. The timing was set by adjusting the point gap as the backing plate doesn't have slotted mounting holes. This means there is no set figure for the gap. If over 8 thou stops the spark there is something wrong possibly with the mechanics of the points, maybe they are staying open or being shorted. 

[cloggy]

I did a lot of digging and finally found mention of an internal rotor points ignition being once offered as GYT kit. Whether it was available in all markets all the time I don't know. Anyway this engine has it, runs really well but not over 8 thou.
The bike also came with a spare external flywheel set up.
I've read here that all DT2MXs came with electronic ignition

[sleepy]

I'd be interested to see the ignition. When I was a teenager I had a DT1 1970 model I think and it came with a GYT kit that the previous owner had purchased for it but not used but only had Head, Barrel, Piston, pipe and carb. There was a different gearbox with some of the early kits but perhaps the local importer only ordered part of the full kit.
I still think you may have a mechanical issue with the points over .008" as electrically it doesn't make any sense. The duel will change with the gap but it would have to be extremely wrong to stop the spark or the rotor phasing could be out but if its all original I'd doubt that was the case. 

[cloggy]

 I'll try and get a photo over the next few weeks
Although it's in my sheds it isn't my bike
The only obvious possibility is that the rotor cam is so shallow that any greater gap leaves the points open for far too long.
The cam is indeed exceedingly shallow, actually it's barely noticeable. Whether it's been modified is impossible to say without finding another. The  bike came recently built but far from debugged.
It is however bloody quick and really clean revving. We had problems with NGKs [counterfeits?] packing after 30mins  so I sourced Champion NC3s  which have lasted and felt much better.