Topic: CB750 K4 points plate is all the way around counter clockwise Why is this?

[seebee750]

I installed a new points plate assembly and the only way to get the ignition timing close is to rotate it all the way counter clockwise.
I set both points gaps at .35 mm
and I cannot get the points for #1.and 4 to open on the F timing mark. They open late at the T mark. #2 and 3 points are opening at the F mark but they are rotated hard counterclockwise and are hitting on the points plate mounting screw. The bike starts and runs but the timing for #s 1 and 4 is late.
 I used the owners manual for instruction and notice that in one photo in the book the same situation exists.
 Is this normal?/ Do I have to open the points gap on #1 and 4 to get the timing correct??

[vern401]

The points on these bikes can be tricky but once set properly it will purr like a kitten.
One side is mounted to the main plate itself the other set of points are on a plate that mounts onto the main plate. What you will need to do is set the ones that mount to the main plate first. Get them to just open at the F mark you can use a light to help in making it almost perfict. Once you have this set opening at the right time and at the right gap lock the main plate down and do not move it again.
Now rotate to the next timing mark. This is the trickiest and hardest part. Be picky with it and use a light to help you. you will be moving the plate the points sit on along with the gap setting. Use the plate to set the opening time and the points adjustment on the plate for the gap. You can rock the engine back and forth a little to check the opening time. It takes a little time to get it wright but is well worth it. Mine is a 78 Supersport which is the last year they had a SOHC.

[Spanner 1]

There has been a lot of discussion about this problem and , unfortunately, some aftermarket points/plates are not up to scratch.
Apparently the points are shorter than the OEM ones in the dimension between the pivot and the rubbing block resulting in a later spark ( retarded ign. ) I can see your plate is all the way ' advanced' to try to compensate........ I had to go back to Honda points for a fix......

[Popwood]

I've been struggling with this problem as well and I have Honda bought points on my 750K5. Thing is, my points plate is rotated completely in the opposite direction as shown in the pix and I can get 1-4 dead on the F mark but 2-3 is retarded by 1/8" or a bit more. I've even elongated the lower left plate mounting slot to gain more adjustment. I also gained a bit more adjustment for 2-3 by closing the point gap to minimum .012 but I'm carbon fouling the plugs 1 and 4. From what I've learned, it the Diachi (sp?) points that may have the wrong geometry. Is this a Honda supplier or just an after market supplier. Frankly, I'm frustrated as all H trying to sort this all out.

[seebee750]

Thanks everyone. My points plate assembly is a Genuine Honda one. I was considering elongating the holes in the main plate to get more adjustment. I only need a fraction to get it bang on.

[HondaMan]

Thanks everyone. My points plate assembly is a Genuine Honda one. I was considering elongating the holes in the main plate to get more adjustment. I only need a fraction to get it bang on.

Wow, those appear to be TEC points, too: they are some of the better ones!

One thing that I think I can see (?) in the picture: is there a small gap between the upper ridge (lip) of the plate and the top casting (where the top screw holds the plate on)? If the plate is of substandard diameter, the points will push the plate downward with their spring force while you're setting things, and this moves the whole geomerty in a retarded direction. This "gap" used to be spec'd at not more than 0.1mm (0.004") maximum at one point (on any of the 3 mounts), but this spec is long since ignored. I have recently seen points plates with as much as 0.12" of 'gap' between the edges of the plate and the mounts. I've been setting curved feeler gages into the bottom edges of the gaps to center the plate while setting it up, then remove them when final-tightening the screws.

In one case, I had to push the plate all the way up to the top to get it to time up, but it had both substandard diameter AND worn points.

[Spanner 1]

Pop and See, it's also possible the stud which passes thru' the points cam ( from the end of the crank ) is slightly bent, it would only take a fraction of a bend to produce a timing issue and this stud is easily bent....' prolly have to take the cam off and set-up a dial gauge on the spindle to check for true while turning the crank.....
+ what Hondaman said.

[seebee750]

Thanks once more.
I did dial in and straighten the advancer stud. It was out 1 mm. When I reattached the advancer unit and rotated the engine, on the electric starter, the wobble in the advancer/points came was back. Some how when I tighten the 6 mm retaining nut it seems to bend the stud??

[754]

Make sure the back of advance unit and through hole are clean. End of crank too, and make sure pin is not bottoming, that could cock the advance unit..

[HondaMan]

Make sure the back of advance unit and through hole are clean. End of crank too, and make sure pin is not bottoming, that could cock the advance unit..

What he said. 
Sometimes the pins are too long, especially if a K0 advancer was fitted to a later bike (as a "performance enhancement"). The K1 bikes had 2 different lengths of pin, too.

Don't use the advancer as the "crank nut" to turn the crank backward, ever. This is often the culprit that bends the shaft. Also, check to see if the hole for the pin (on the end of the crank) is ovalled: many are from years of people pulling on the big nut. This can tilt the advancer, making it wobble and cause timing jitter, too.

[seebee750]

I am going to check those things,
thank you