Timing Light Works on One Wire, not on Other

[PHeller]

I've static timed my bike a few times now, and I can't seem to get it right. Stock ignition, stock charging system, puts out 14 volts at idle, and sometimes will fire on the first kick.

When I attached the timing light to the right side wire (top points) it doesn't work. It's intermittent. Attach it to the left side wire and it works as normal.

I tried testing the coils, but couldn't get anywhere near the correct ohms on either coil (bounced around alot).

Is this a pretty good determination that I've got a bad coil? Or are the points not correctly set? I figured if I can set one good then the other should be close after multiple tries.

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[xjwmx]

If the light is intermittent, I'd take it to mean that the spark is intermittent. If you watch the light and listen closely you can probably hear it missing. If you suspect the coil (I guess you have one for each side), it's the easiest thing in the world to test with a meter.

 

[PHeller]

Like I said I tried testing it across the leads but the OHMS bounce all over. I couldn't tell you if it read 2.75 volts because it wouldn't sit still.

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[xjwmx]

Then you need either a new meter or training on how to use it. Disconnect the coil before measuring it, if you didn't.

 

[5twins]

Switch the coils from side to side and see if the problem follows. Substitution is the easiest way to diagnose electrical problems. If no change, switch your condenser leads from side to side. Your symptoms sound like a condenser going bad.

 

[PHeller]

I probably don't know how to use the meter but no matter which setting I use in testing resistance I don't get 2.50 or 2.75 or anywhere close.

Which setting should I use?

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[retiredgentleman]

Some of the numbers here are suspect. These bikes don't put out 14 volts at idle............more like 13 to 13.5 volts. You mentioned ohms and then said 2.75 volts. If you mean 2.75 ohms, that's not the correct range.

With points type coils, the primary should be 4 to 5 ohms. Your meter leads may be around 0.5 ohms, so you should measure 4.5 to 5.5 ohms. Are you using the correct coils for points?

Timing lights seem to be sensitive to polarity. Try reversing the primary wires on the right side coil to see if the timing light will then work.

 

[xjwmx]

Which setting should I use?

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What settings ya got? The black wire plugs into 'com' the red plugs into the Omega symbol. The dial goes to the omega symbol. I haven't used a meter what wasn't auto-ranging since about 1985, so I don't remember what to do if you have to choose a range.

Is it still just jumping around? Press hard with the probes using their points, or try attaching it with little jumper clips.

Might be simpler to take 5twins suggestion of substituting parts.

 

[PHeller]

I meant ohms so we're good there. Battery tests fine at 12 volts.

I checked my point gap for the Right cylinder and it was a little large, so I adjusted that. It seemed to start easier, but blew the carbs off again as it died at idle.

So, I'll check timing with light again and see if it works on the Right cylinder.

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[XSLeo]

I have found that with my timing light if I get an intermittent flash I turn the clamp over on the plug wire and it flashes right.
The clamp is polarity sensitive. If the spark goes through the clamp backwards it won't read the spark well and does the intermittent thing.
When I got the light it had an arrow showing which way the clamp should go. That dissappeared after the clamp got on a hot exhaust a few times.
Leo

 

[PHeller]

I found out that my timing/points gap on the RH cylinder was all messed up.

When I switched it over to the left cylinder it worked as normal.

I had a feeling the timing might have been way retarded as it was blowing the right side carbs off, so I adjusted the gap on the RH and moved the whole backing plate a few degrees clockwise.

Sudden, the bike idle better, started better, and revved more smoothly.

It also quit blowing the carbs off AND I was getting warmth out of both pipes, something I didn't have before.

I got it idling at 1200rpms, but didn't have a chance to throw the timing light back on it.

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[PHeller]

Update: Still not working. When I put the light on the LEFT side wire, its spot on timing.

When I put it on the RIGHT side wire, its all over the place, not consistent.

I also noticed at the top of the right side compression stroke the cam lobe isn't raising the upper points...

I can get it to idle at 1500rpms, and the left cylinder advanced to the mark as normal.

It's just that right cylinder that has got me flustered.

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[5twins]

Yes, I think you need to start from scratch. Gap the right points, set the right cyl. timing, then do the left. Moving the entire backing plate to set the right cylinder timing will change the left cylinder timing as well. Then you need to reset it moving just the half plate the left points are mounted to. Changing the points gap also changes the timing. That's why you need to set both points gaps first before even doing the timing. If you've been continually sticking an oily feeler gauge in the right set of points to gap them then you've probably contaminated the points faces with oil. They will misfire or not fire at all once that happens.

 

[PHeller]

Thing is I've set them from scratch probably 4 times now and every time I'm getting the same issue...right cylinder is out'a wack.

Condensers are probably original, and although the points are NOT burnt, that could be the reason behind the messed up timing light on the right side.

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[5twins]

You haven't tried switching the condenser leads yet???

 

[oldbiker]

hi you may find that alot of timing lights have a small arrow on the clamp for the wire ,,, its worth checking,, as when i purchased my timing kit,, i didn,t realise it was marked,,, regards oldbiker

 

[XSLeo]

It don't happen often but the wire to the points gets chafed and shorts to ground. That might be it.

 

[PHeller]

I switched the condenser wires and no change.

For all I know both cylinders are running just fine. I haven't had the bike out on the road yet to know what power is like.

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[bloodthirstysystem]

set the points with your ohm meter before trying with the timing light.

positive lead on points, negative on motor..
rotate the motor by hand, when the timing mark is just approaching the F mark the points should just begin to open..

you can get pretty damn accurate with the ohm meter. i always did this way and only used a timing light to make sure it was advancing properly. do the right cylinder first, then left. make sure you're setting the points on the compression stroke, not exhaust stroke. some point gaps like to be set to the minimum tolerance, some like it at the max

 

[bloodthirstysystem]

and after setting, clean the points because you probably just got them dirty