Second XS650, 1977 Standard

[FrankS]

I wouldn't be adverse to a build your own option. I'll read that thread.

Last year I made a mistake and bought a regulator only unit for my CB750 which I did not return. Could I use that as half of the "project?"
It's actually the original rectifier that causes the fuse to blow on this bike.

 

[Jim]

Last year I made a mistake and bought a regulator only unit for my CB750 which I did not return. Could I use that as half of the "project?"

https://www.cb750.com/ is one of our sister sites. I'm sure you could find a diagram over there that will answer that question for you.

 

[jaybar6]

the xs650 is a greedy, cuckoo!

 

[jaybar6]

Hi frank, i have a solution of sorts, on your 1st xs, the one with a PMA. it had a mechanical regulator, which was redundant because of the PMA. Use that in the second xs with a normal rectifier (assuming the regulator works!). The1st xs needs the Lucas 200W rec/regulator because of the PMA.

But before all this expensive electrical components buying, you need to find all the shorts.

 

[FrankS]

Thanks for your suggestion jaybar6.

The silver 650 has a pma and new reg/rect. I’ve now removed the old regulator.

The blue 650’s old rectifier causes the fuse to blow. I’d like to replace both the defective old rectifier and the old regulator with a new combo unit.

 

[FrankS]

I was distracted from the xs650’s by my Honda cb450 that was much closer to running. After a few new carb parts and adjustments of timing and valves, it’s now a runner!

My next foray into the xs650’s will be setting timing and valves on both. The blue bike’s points and plate adjustment screws were so mangled I had to drill off their heads and replace them.

 

[5twins]

Unfortunately, that's kinda typical, lol. You're in for a treat dealing with the dual points system, it can be a bear to get set perfectly. Consider it two separate little ignition systems, one for each cylinder. To get it perfect, besides setting the timing and points gaps, you want to match those settings between the two cylinders. A dwell meter really helps with setting and matching the points gaps, and it's really the only way to accurately gap used points.

 

[FrankS]

Something is out of sync or I’m really dumb. Equal probability of both.
With the fire mark lined up and the right side cylinder on compression stroke, the cam lobe is nowhere near the points lifter tab. Marked with a black dot on the end

 

[FrankS]

Sorry that last pic is 90 degrees rotated.

 

[5twins]

It's possible your advance unit is assembled incorrectly, and that would throw the timing off 180°. See the end of the locating pin slot peeking out from under the retaining nut and washer on the points cam in your pic (right next to the black dot)? There's a similar locating pin in the little disc on the advance side and it should point in the same direction .....

Problems can arise because the hole in the end of the advance rod goes all the way through. This means the locating pin can be installed sticking out of either side. Only one way will give you the correct timing, the other way will throw it off 180°. Yamaha was kind enough to put slash marks on the advance unit backing plate and the little center disc to help with proper assembly .....

 

[Jim]

You fire mark is the lines between the F. You're a little past that, but your points look (almost) correct. Looks like the right points are just starting to open. Past the fire mark they should be open, but you're almost where you need to be.

 

[Jim]

With your points cam in the position shown, the left points should be open. Looks like they're closed.

 

[FrankS]

May have found the solution based on 5twins and Jim’ suggestions. I think the shaft that goes through to the mech advancer was installed 180 degrees out because the donut thing that catches the locator pin was flipped. The directional arrow engraving was facing towards the engine. Will confirm later today.

 

[Its been a long time]

May have found the solution based on 5twins and Jim’ suggestions. I think the shaft that goes through to the mech advancer was installed 180 degrees out because the donut thing that catches the locator pin was flipped. The directional arrow engraving was facing towards the engine. Will confirm later today. View attachment 336308

Yes, the line on the backing plate is 180 degrees away from the line on the centre advance donut. Remove the bob weights and turn the donut 180 degrees so the marks line up.

If you haven't already done it, pull the advance rod out, clean it, grease it and put it back.

 

[FrankS]

1. My computer died so I’m stuck with my phone with which I cannot draw on photos to point at things.
2. My mistake in thinking the white mark next to the alternator index line was the index line. Close but not quite.
3. Disregard the points gaps. They are not set. Weird that when I set the one gap where the lobe is, when I rotated the engine they closed but then opened again.
4. The synchronization is still off by about 45 degrees. I’ll try to post photos in a bit. My son thinks he can enable drawing on pics on my phone.

 

[Its been a long time]

1. My computer died so I’m stuck with my phone with which I cannot draw on photos to point at things.
2. My mistake in thinking the white mark next to the alternator index line was the index line. Close but not quite.
3. Disregard the points gaps. They are not set. Weird that when I set the one gap where the lobe is, when I rotated the engine they closed but then opened again.
4. The synchronization is still off by about 45 degrees. I’ll try to post photos in a bit. My son thinks he can enable drawing on pics on my phone. View attachment 336310

Provided the heel of the points is contacting the cam, they will open/close. Timing can be anywhere. Points still open and close.

 

[FrankS]

Phone is working. I’m back in the garage.

 

[FrankS]

1. Advance unit oriented correctly now.
2. Gap set at widest opening to 0.014”
3. Fire mark correctly set on compression stroke of right hand cylinder.
4. Points lobe about 45 degrees out, points not open.

 

[FrankS]

Just to see, I swapped the points cam rod (what’s it properly called?) with one from my silver 1978 Special. It looks like it could work at the extreme points plate position. But regardless, it’s orientation is different from the original.
I’m thoroughly confused.

 

[FrankS]

In my garage.