Mark,

Have you or anyone else experimented with spark plug caps of different resistances? I know that ignition coil secondary resistance measures are to be made with plug cap removed and for the DT1 should be in the 5-6k ohm range.

Plug cap resistance in Glen's Yamaha suggest 5k ohm. My cap resistances (have 2) are in the 9-11k ohm range. I know NGK makes zero resistance caps. Will reducing resistance aid in creating a "hotter" spark and or improved performance?

Norcal

Now you're talking about "voodoo"

As a project in college, I built and tested a few ignition systems for a single cylinder two stroke.... it was cool to have the test equipment, including a dyno.

Until the spark jumps the gap, the resistor does nothing compared to the "resistance" of the air gap the spark needs to jump. Once the current start to flow, the resistor starts working and "slows down" the flow of electricity making the spark duration longer.... but the resistor does weaken the spark a little...

In a system designed for a certain resistor, removing it will slightly increase the spark energy BUT the spark duration is shorter which can cause misfires.

Adding too much resistance is probably worse... can weaken the spark energy too much and any extra spark duration gained is not helpful... this commonly happens when someone runs a resistor cap and a resistor plug because that's what the shop sold them. Misfires and more easily fouled plugs can be the result.

My advice is to stick to the resistance recommended by the engineers... usually 5k ohms for a Yamaha. OR run a non-resistor cap and a resistor plug. (Not both)

Cheaper option is to use the resistor cap and non-resistor plug... which is how most models came.

All interesting info above MarkT & something i've never really understood or i mostly thought resistors were for stopping electrical interference.
Now just to really get ya all thinking--[or show up my stupidity] Does a longer plug lead retard the ignition?.

Mark,

I received the Okuda TC-2030 timing tester and it works the same as yours. Finally I have a tool that will indicate precise consistent point opening. I also made a dial indicator tool out of hardwood for holding the dial indicator over piston top.

With this tool, I simply locate piston .126 in BTDC and adjust points until timing tester sounds. At this point, is where I had difficulty maintaining point opening position after point anchoring screw was tightened.

I was finally able to fix this situation by making detailed point opening adjustment after points were secured with anchor screw. This allowed me to obtain exact point opening relative to piston position.

Bike runs nice. Thank you for your input and help.

BTW. There are a couple of these Okuda TC-2030 timing testers on ebay now for $33.00

So when you say you set your points at a tight "15".  How is this done...rotate the flywheel to what point?  TDC or F?  Hold flywheel...losen point screw...set gap at 15 then tighten down points...check.  Something like that?  Pls explain in more detail.  Tks   I have a 69 DT1b that runs horribly with no power at all...but has very good compression.  I'm suspecting something in the ignition system as all else is clean and good.  Tks   Kinda would like to know how to rig up a light...or 12v testor connected to a good ground and the points (where) and then when thelight comes on as the points open...make sure the magneto is at the F position?  Something like that.  Tks for your help.  Just ordered new points and condensor, going to try again following your reply. 
 

What i'd do if i didn't want to get too technical is loosen the points screw & align the timing tab with the notch in the flywheel slot--call it F--then tighten the screw. Bit of a fiddle to get it opening right on the mark as sure a hell it moves when tightening the screw. Cigarette paper used to be the 'go' but you'd need 'clean as' points to get a good feel. Theoretically then if you move the flywheel around until the points are nearly disappearing off the slot then the open gap should be within 12--15 thou. You get pretty good at eyeballing the moment of separation of the points & also eyeballing 15 thou or less.
But--i'm wondering if your exhaust is blocked or severely restricted from what you say about performance. My old early DT1 goes like hell & revs right out. & not touched the points for--can't remember, maybe 30 years haha. I'll just add that if the points fiber heal has worn right down then the gap could be hardly opening retarding the timing. Sorry--just woken from a nana nap lol & not thinking too clear so others might have a different idea on things, all good. Video with good audio would be great please.

Just one more late thought regarding timing & performance. Just be sure the crank key is ok, because if damaged or in particular broken off it'll send the ignition timing way off. Got to be tightened well--very well.