Has anyone upgraded their 1974 dt250 to a Rex’s speed shop 12 volt kit?  The actual kit is a RMK6-12 volt. I’m having a heck of a time getting this thing timed. I have the timing light on it and it is about perfect no matter how much I rotate the stator. Rex suggested rotating it 1mm at a time which I did. The bike will run and idle fine. At 5500 rpm it starts to cut out. Was running fine before I put the kit on it. It has always been finicky with timing but I can’t seem to find the sweet spot this time. Any help will be much appreciated. 

Just my random thoughts & timing isn't an exact science as regards misfiring at 5500rpm. I think you might be looking for the wrong cause but happy to be proven wrong. You say "was running fine before fitting the kit" so is there a wiring fault the way they're connected. I live in the past--& still have points ignition. I won't say exhaust or carb because was ok on original mag--but i'll say it anyway lol.

Thank for the advice RT325. I 100% agree with you about it possibly being the carb or something other than the timing. I’m going to take the kit off this weekend and put the points back on it to test my theory. These are old machines so it is quite possible something else broke during the change out. Almost sounds like the pipe is clogged but I had one of the guys on the site make it a “sleeper” pipe a few years ago. It could be plugged I guess. Changing back to stock will verify.