Can’t rotate R points enough to set.

[XSAndy]

Hey All
Just been doing some long due maintenance including a tune up On the XS650SH. Points model here in Australia in 1981.
Set the cam chain, then points gap, then got out timing light to set the timing.
When I start with the right side I can’t rotate the plate anti clockwise enough to get the timing mark to lie inside the F region properly. It just makes it to the first line of the F region. When I add throttle the line advances to well before the advance mark.
so It seems that if I could rotate the plate further I could fix both issues. The left side sits in th3 zone and on advance sits over the advance mark. Any thoughts?
Cant imagine that I should need to take a dremmel to the R backing plate.
I did consider sanding a tiny bit off the plastic pad that sits on the cam to have the points open later. Do you think that might solve the issue?
Only other options are to buy new points and see if they are better or buy whole new backing plate and points assembly to see if that solves the issue.
Bottom line is I’m open for ideas.
Thanks in advance. Pardon the pun.

 

[gggGary]

Worn parts create issues, possible suspects;
cam chain stretch.
worn points assemblies
worn advance mechanism.
The simplest thing to try is adjusting the points gap on the RH side, going up or down a few thou from the .014" can help drag that cylinder's timing into line. even with a larger smaller, gap there's plenty of dwell left for proper spark.
You can glue shims inside the advance stops to reduce how far the weights move out. A long time ago Yamaha recommended bending in the stops but found they are brittle and will then break at the bend.

 

[DogBunny]

Cant imagine that I should need to take a dremmel to the R backing plate.

Parts are likely worn as Gary said, but I see nothing wrong with Dremmeling the plate as a quick fix.

 

[XSAndy]

Worn parts create issues, possible suspects;
cam chain stretch.
worn points assemblies
worn advance mechanism.
The simplest thing to try is adjusting the points gap on the RH side, going up or down a few thou from the .014" can help drag that cylinder's timing into line. even with a larger smaller, gap there's plenty of dwell left for proper spark.
You can glue shims inside the advance stops to reduce how far the weights move out. A long time ago Yamaha recommended bending in the stops but found they are brittle and will then break at the bend.

Thanks Gaz. I use a 9 and 10 thou gap that I had recorded on rebuild many years ago. That was either given to me or found to be better than the recommended 11-12 thou. I’ll experiment with that short term with an aim to replacing everything long term. I guess that’s the price you pay for wanting to remain stock. I will be interested in which side was 9 and which 10 and see if that makes a difference or correlates.

 

[XSAndy]

Parts are likely worn as Gary said, but I see nothing wrong with Dremmeling the plate as a quick fix.

Cheers dog. Might see if I can get some good things going by adjusting the points gaps a bit first.

 

[Jan_P]

Not read through and perhaps stating the obvious . I have not had Points for 20 years but I do remember that there is a Possibility to adjust the 2 point halves relative to one another .

If I recall Right at half past 12 is the screw for holding the point 2 of them
11 o clock the one for rotating both points equal amount 2 of them
But if I remember right the screws half past 9 and half past 3
can adjust the relative position on points .. I am certain there is a possibility to adjust if I got it Wrong with what screw does what.
Please disregard if this is already Done and Known


https://www.xs650.com/threads/setting-the-points.57676/

 

[toglhot]

Just be aware, if the chain is stretched it will effect the cam and crankshaft sprocket toothing. While the cam sprocket isn't a problem, the crankshaft sprocket is.

 

[XSAndy]

Hey Hey Hey. Well here’s the solution.
Changed to points both sides to 8 thousandths and not really sure they were well set at 9 and 10 before either. Rather loose.
This gave me plenty of plate rotation leeway to set up both sides timing perfectly, on the centre of the “F” zone with the timing light.
Key lesson= the points gaps are critical to giving you the leeway you’ll need to get the timing spot on.
Shouldn’t be a surprise but sometimes you’ve just got to experience getting it wrong to see the critical steps in getting it right.
Maybe that’s why mechanics do apprenticeships?
Many thanks to everyone for your inputs.

 

[gggGary]

Before anyone goes off about dwell time, an old school example a V8 car motor on a point distributor has 8 spark events per cam revolution compared to our one so the V8's dwell is about 1/8 of ours and would rev to 4000 RPM just fine, or the equivalent of 32,000 RPM on a single bump points cam.
Factory suggests a gap of .012 to .018" (.3 to .45mm) So your small gaps should be thought of as a stop gap (wink) measure and perhaps a warning about the cam chain being stretched. A new set of QUALITY points wouldn't hurt either if the rub blocks look worn. We'll assume the points have been filed or sanded, cleaned. Points cam should be inspected for wear, condensers measured or replaced. If you aren't racing and it runs good getting about 50MPG in moderate use, life is good.

 

[Jan_P]

And starts .. .. !!! --> " life is good. "

 

[5twins]

And if you insist on sticking with the points, you really should get yourself a dwell meter for setting the gaps on them. It's the most accurate way to set the gaps and the only accurate way to set used points. Used points develop pits on the points faces and that's what the spark jumps between. You can't measure between the pits with a feeler gauge. The gap you set between the faces will be smaller than the gap between the pits where the points are actually firing. For that reason, if using a feeler gauge, it's best to gap used points at the low end of their range, say .010" to .012". But, you still won't know for sure what your gap actually is unless you use a dwell meter. It measures the gap electronically.

 

[toglhot]

On another forum I posted my dual lobe, single points mod, there was much derision, the knockers reckoned the points would float???