76 XS650 won't start after carb rebuild

[Vivianthebarbarian]

Finally got back to the bike after a busy week. I set the gap on the points (had to run to town to get a replacement screw as one was so chewed up it was unusable). They didn't seem far off. Then I went to set the ignition timing. Turned motor so R cylinder was on compression stroke and hooked a light on the top set of points and the other leg to ground. Turn on ignition and the light comes on. ok, so i turn engine with a wrench but the light stays on....even if I go all the way around. Now I'm confused. Does anyone know what this means? I mean most likely it means I screwed up somewhere...but could it mean I found something that is broken?

 

[Jim]

Provided you have the light connected correctly, the power to that light is diverted to ground when the points close.... light goes out.
If the light never goes out, most likely the points aren't closing.
Take a screwdriver and touch the point contacts (shorting them together).
Does the light go out?

 

[Vivianthebarbarian]

Yeah, the light goes out. Sounds like I need to go back and regap the points. The only feeler gauge I had in the range my book specified (0.012-0.016) was a 0.015 and I was wary of making them too tight and opening them against the spring pressure when setting them...so I probably set them too loose.

 

[Kevin Werner]

Yeah, the light goes out. Sounds like I need to go back and regap the points. The only feeler gauge I had in the range my book specified (0.012-0.016) was a 0.015 and I was wary of making them too tight and opening them against the spring pressure when setting them...so I probably set them too loose.

Depending on your feeler gauge set, you can stack them. 0.004 and 0.008 gives you 0.012. Do you have any that small?

 

[5twins]

And be sure to thoroughly clean the blades before using on points. Any oil at all can contaminate the points faces and they won't fire. Also, if the points are used, set them near or at the minimum spec (.012"). Used points develop pits on the faces and that's where the spark jumps. You can't measure between those pits with a feeler gauge. The gap you measure will be smaller than between the pits.

 

[lakeview]

Your starter button may work again if you clean the points in the safety switch under the right side cover.

 

[Vivianthebarbarian]

Your starter button may work again if you clean the points in the safety switch under the right side cover.

When poking around under the right side cover trying to figure out where the safety switch was, I found out the blue and white wire had a very loose bullet connector (it came apart when I poked it). Put that back together and now it seems to work at least part of the time.

 

[Vivianthebarbarian]

Hmmm, still having trouble with the points. I purchased a new set of feeler gauges that had a 0.012 blade and cleaned off the oil with brake clean and paper towels, then set the points again with the smaller gauge and leaving them tighter this time. Went to time them and the points (at least on the top one) still don't close! The light stays on even when turning the engine all the way around. I can see them opening and almost closing, but the light stays on unless I short it with a screwdriver...then it goes off. Wondering if these points are worn to the point that I need to replace them?

 

[Jim]

You set the points with the (points) cam at it's highest point.... most lift.

 

[5twins]

And it's also possible to have the points cam installed backwards on the advance rod. There's a lip around the bottom of the cam. If installed correctly, the points rubbing block rides above that. If on backwards with that lip facing out, the points rubbing block rides on the lip and the points will never close. On the left below, you can see a properly installed points cam, with the lip on the bottom .....

 

[jpdevol]

As stated; rotate engine until cam apex is aligned with points' rubbing block, then set gap to .014" (or whatever spec is called). In this pic, the cam has passed the rubbing block a bit (not aligned).

 

[Vivianthebarbarian]

You set the points with the (points) cam at it's highest point.... most lift.

Yes. I watched the points open as I turned the engine over with a wrench, then used a feeler gauge to help me find the spot where is was the widest open. Then used a 0.012 feeler gauge to set the points, but they still aren't quite closing...I guess. I mean it looks like they close but the light stays on unless I short them.

 

[Vivianthebarbarian]

As stated; rotate engine until cam apex is aligned with points' rubbing block, then set gap to .014" (or whatever spec is called). In this pic, the cam has passed the rubbing block a bit (not aligned).View attachment 219668

Yeah, I have trouble telling where the cam apex it just looking at it, but watching the points open then using a feeler gauge to find the point of widest gap seems like it should work.

 

[Kevin Werner]

Try setting points at 0.010 or 0.08? Or set the points till they just close and the measure the gap when they open?

 

[Jim]

Yes. I watched the points open as I turned the engine over with a wrench, then used a feeler gauge to help me find the spot where is was the widest open. Then used a 0.012 feeler gauge to set the points, but they still aren't quite closing...I guess. I mean it looks like they close but the light stays on unless I short them.

If the point gap gets bigger and smaller, then as 5twins asked, the cam is in correctly. That gets us down to either the wrong cam is in there.... highly unlikely....
or... you're doing it wrong... more likely.

If you rotate the cam to the highest spot, set the points correctly, they'll close.
Give us some good closeup pics of the points housing so we can see what's going on.

 

[Vivianthebarbarian]

HAA! Progress! My book said something about taking a business card and running it between the points until it came out clean. I did that (with a doubled over index card) and now the light goes off and on. Seems it was just too dirty to make contact?

 

[Kevin Werner]

HAA! Progress! My book said something about taking a business card and running it between the points until it came out clean. I did that (with a doubled over index card) and now the light goes off and on. Seems it was just too dirty to make contact?

Yea you. Success and a learning moment. Keep it up. Sincere

 

[5twins]

Points should be replaced about every 12 to 15K miles even if the points faces still look good because the spring steel strap that snaps them closed can get weak. Then you get a situation similar to yours - they close up but not tight enough to make contact. Of course, your issue was dirty points faces, but do consider replacing them if the mileage on them is high.

 

[Vivianthebarbarian]

Still having trouble. I am trying to set the static timing on the points and I can't seem to adjust it enough to get the mark on the rotor to line up with the F mark on the stator. The closest I have been able to get it is having the light come on when the mark is half way between the F and the T. The plate can't seem to turn any farther in the direction it needs to go. Tempted to take it off and grind the holes a little bigger, but I feel like I'm just being stupid and can't see where the problem is. I did adjust the cam chain tensioner before doing this.

BTW, I left the top points set at the best that I could get them (about halfway between the f and t) and was able to set the bottom points at the f. I wondering if this is going to be close enough or not.

BTW #2-Tried to upload a pic of the points plate but I can't upload picts from my phone when I'm out at the farm, too poor a connection maybe...it just says upload failed every time I try.

 

[Kevin Werner]

Sorry, last time I set points was my wife's 66 Mustang in 92. 30 years and 10k miles ago... Still runs like a top.