Many of us have seen these $4 and $5 Daiichi points for these SOHC4 bikes lately, and have had some poor luck with installing them. Last weekend, someone came to my backyard for a tuneup with a brand new pair of these, and no matter what we tried, the timing was 'WAY advanced when the gap was set even to the minimum .012" value: the slots on the timing plate would have had to be widened almost 3/8" just to make them reach the "F" mark(s) (and I don't have a mill for that kind of accuracy). So, we could not install those points. I could get them to set up with a points gap of .009", but this small gap will cause the contacts to burn very quickly because they do not separate far enough to extingush the arc.
I've had this happen 4 times now, this year, on 750s and a 550.
So, I decided to do an in-depth study today, since it's snowing here in Denver. Below are some pictures where I compared the Daiichi to some TEC points (high quality units) that timed in perfectly at .014" gap and middle of the points plate slots. One of the pictures shows the TEC points on the left (by my finger) and 4 sets of Daiichi points to the right: you can see that even from points set to points set, these points do not even look the same: check out their grounding arms. This will cause myriad timing issues when trying to install them.
But, these points are everywhere, and because they are so cheap, will probably remain around for a while. I decided to measure their screwy geometry to find out why they are so far off, and below is shown what I've found, measuring the ones you see in these pictures. The Daiichi numbers shown are averaged over the pair of right and left points, and the TEC numbers are from the one set that I know is good.
The result: if you are going to use these points, the first thing you must do is widen the slots on the points plate, to the right as you view the plate on the bike, so that you can retard it far enough to reach the "F" marks while the points gap is in the .012" to .016" range. The geometry situation is: the rubbing foot is a different length and the distance from mid-foot to the pivot center is too short. Together, these add up to almost .005" of mechanical error on the design of these points. That explains perfectly why I had to gap at .009" to make them time up right.
(BTW: Not to turn this into an 'ad', but...if the Hondaman Ignition is used, this .009" gap is no problem. I've had this on my own bike at .011" gap on 1-4 and .012" gap on 2-3 for over 2 years, now...there's no arcing problem then. That's one solution.)
