Bad coil? Bad cap? Bike won't stay running

[KSAL]

81xs 650
Straight exhaust cut off just behind foot peg
K&N filters
Can't remember exact jets but around 147.5main 42.5 pilot (I think)
Pamco
Pam
Kickstart only
47,000uf 40v cap (6mOhm ESR, 10 mOhm impedance)
Basic electrical- headlight, brake light

So my bike ran like a million bucks last year probably put on 2-3k miles. Stored it over the winter, used clean gas but noticed it was starting to stumble a little bit when I would give it a little gas mostly when I was cruising at a regular speed 45-55mph and go to accelrate. It actually started to do this at the end of last year.

So at 45-55 giving a little throttle it would hiccup a bit but continue to ride fine and maybe hiccup a few times during the ride.

I changed jets and the WOT seemed to get a little better, didn't hiccup as much.

I rode it about 30miles and it was fine, no issue whatsoever ever, on the return ride home I made it about 15-20 miles and it started to stumble and run terribly, I thought I might be running out of gas so I stopped and toped off, continued to ride a mile or so and it was falling on its face about 1/3 throttle but would kind of run backed off from there.

Made it about .5 miles and it died. I let it sit for a few mins on the side of the road, the bike fired up and made it another .5 miles before dieing for good. Wouldn't kick over, start, nothing. Just kick, kick, ,kick kick (next day sore calf!!) Loaded it on a trailer and brought it home. Watched game of thrones and made food went outside and it started right up.

Went to ride it the following day, started right up and let it idle for a bit, after about 2mins went to rev the throttle up and it died. ( all that was a few weeks Go) check the spark then it was fine.

Started the bike up today checked my cap and it had 14.23volts let it idle for a bit then went to rev it up it stated stumbling and running like crap at about 1/3 to 1/2 throttle (held in that position, not reving up and down) and it just a stumbled and died out. PLEASE HELP

 

[Ghetto]

Almost sounds like vapor lock. My bike was doing almost the same thing. Ended up being a bad seal on the gas cap. Worth a look.

 

[KSAL]

Any way to test that to rule it out? I'm assuming if its a bad seal I could take and cover it with my hand right?

 

[Ghetto]

There is a little hole on the back side of the cap. Make sure that it isn't clogged and that you can move air through it. Mine was gummed up. Got it all free and clear and the problem went away.

 

[TheRealSpinner]

Reading this post is like narrating my experience with my 71... now I'm wondering if I had a vapor lock problem.

I'm in the middle of a build (with that motor), so I might test to see if the new tank (and cap) fix the problem. That'd be awsome if it's the cure.

 

[pamcopete]

Most likely a carb problem, but to eliminate the PMA regulator and cap, try running the PAMCO directly from a battery that is not connected to the bikes electrical system.

Also, you mention that you saw 14+ volts on the cap at idle....what was the voltage when you revved it up and it stumbled?

 

[gggGary]

Could be either but I'm leaning towards charging system issues. Still the stock rotor stator set up? when's the last time you checked your brushes?

 

[Tomterrific]

I'm thinking charging too. I like the idea of hooking up a charged battery to see if that eliminates the problem. Since it is a capacitor/battery eliminator the R/R is suspect. Which regulator is on the bike?

Tom

 

[KSAL]

Ok little update. It is not the vapor lock, as my gasket has a little tear at the gas tank so it's getting plenty of air through there.

Now when trying to diagnose the bike I can't get it to run more than 5-10 second to test anything.

I tried unhooking the cap and plugging the positive and neg into a battery and I got nothing.

If the rec/reg is to blame could I unhook that, then re-hookup the battery and it should run just off that?

Also I tested the coil and from primary to primary I got 4.4, but when I went from plug cap to plug cap i got .778 (auto value setting) could this be the issue even if the primary's fall within spec?

 

[KSAL]

Also thoroughly cleaned the carbs and jets back to when it ran perfectly last year

 

[pamcopete]

Ksal,

The recommendation was to temporarily wire the PAMCO and coil directly to a separate battery sitting on the floor, not connected to the bikes electrical system in any way. Your test may have eliminated the capacitor, but you could have issues elsewhere in the bikes electrical system, so by using a separate battery that is not part of the electrical system, you are eliminating the entire electrical system from the issue.

Also, please throw that autoranging meter in the trash, or re-gift it to your brother in law and go to Harbor Freight and buy one of their $3.99 meters Item #98025. Auto ranging meters try to do the thinking for you which is not good when you are troubleshooting.

Here is a recommended test procedure for the coil and PAMCO:

Testing the coil:

1. Using the lowest scale on the meter, measure the resistance between the primary terminals with the wires removed. Should read from 2.5 to 4.5 Ohms.
2. Using the highest scale on the meter, measure between one of the primary terminals and the center core of the coil. Should be infinite resistance. (open)
3. Measure between one of the primary terminals and one of the plug wire terminals. Should be infinite resistance. (open circuit)
4. Measure between one of the plug wire terminals and the core of the coil. Should be infinite resistance (open circuit)
5. Measure from one plug terminal to the other. Should be 15,000 to 20,000 Ohms

Testing the PAMCO

1. Use a voltmeter and check for battery voltage on each of the red/white wires with the key and kill switch are turned on.
2. The dual output coil has to have both spark plug wires connected to a spark plug at all times.
3. To test for spark, connect one of the spark plug wires to a spark plug that is grounded to the engine.

To test for spark without having to turn the engine over, do this procedure:
1. Remove the PAMCO rotor.
2. Remove the locating pin in the advance rod.
3. Reinstall the rotor, but without the pin.
4. Replace the nut holding the rotor on loosely. This will allow you to spin the rotor to produce a spark without having to turn the engine over.
5. Connect one of the spark plug wires to a spark plug that is grounded to the engine, but not installed in the engine.
6. Make sure that the other spark plug wire is connected to a spark plug in the engine.
7. Turn on the ignition switch and the kill switch.
8. Spin the rotor while looking at the gap in the spark plug for a spark.
9. Turn off the kill switch and the ignition switch.

 

[KSAL]

Well Pete my hat is off to you!!!

Had I just listened in the first place and took the Pamco off i'd be done and have 500 miles on!!!!

Took off the Pamco Cover and a tiny little screw, 2 washers and 2 pieces of plastic were sitting in the cover as i took it off.

I"m assuming that is the metal sensor that senses whatever and because it wasnt screwed tight to the bike and everything rattled loose it wasnt sensing when to send spark to the plugs, therefor no running or starting of any kind

Problem solved!

 

[conner]

hey guys im having a similar problem, my left cylinder fires fine but my right cylinder will only fire sometimes, ive replaced the plugs and plug wires and it didnt really help, im not sure if its an electrical issue with the coil or if its the ss super shorty carb i mounted with a custom fabbed pipe that splits and goes into both cylinders from the left side.. if anyone has ideas it would be much appreciated to here them

 

[KSAL]

Update-

Took the bike out for about 150 miles yesterday ran great except for two little hiccups hoping pamcopete can maybe shed some light on.

After riding to the first spot which was about 20 miles away, I let the bike sit for a few hours and when I went to start it, it started and ran for 1 mn and then just died out.
Kicked kicked kicked nothin. Drained the carbs, looked at the pamco, tried to check spark nothing seemed wrong. I somehow got to the point of messing with the advanced timing rod. I pushed it in spun it 180 put its little cap and nut back on.
Fired right up.

Left there rode about 100 miles stopped at a friends house for about an hour, went to leave made it just out of his driveway and its died off.
Checked the pamco, it was fine, but I spun that advanced rod 180 again put to together and kicked right over!!

Heading out today so there might be more info to come.

 

[KSAL]

Today was a bust! Made its about 20 miles it just died, didn't stutter at all,,just seemed like it lost all spark. Stopped for 2 mins it kicked right over and I turned around, made it 3-5 miles, dies again sat or 2 mins in the side of the road started right up made it a mile died again, did that 2 more Times only making a mile or so.

Ended up picking it up with a truck.

And now I have no idea what the issue is

Compression after 4-6 kicks WOT was 150

 

[TwoManyXS1Bs]

Fuel restriction?

 

[KSAL]

I Don't think it has anything to do with fuel, you would think a fuel issue would be more obvious and consistent. Like i could only go 1-2 miles or something.

My issues have no rhyme or reason it will run great for 20-40 miles then die out, or go for 1 mile and die out.

 

[TwoManyXS1Bs]

KSAL: Any signs of scraping, dings, dents, scunge, rubbing, etc, on the Pamco electronic components from those loose pieces flying around in there?

Conner: Check-out this thread: http://www.xs650.com/forum/showthread.php?t=27063

 

[KSAL]

I didn't see any visible signs of that kind of wear. I'm curious if maybe as the screw started coming off if that shorting would damage the electronics if it wasn't able to send a good signal???

 

[TwoManyXS1Bs]

That's what I was thinking. Another member here had intermittant problems, and on close inspection, he found the hall sensor (looks like a to-92 transistor) had bent to the side a little, and 2 legs of the device were bent close enuff together to look like a possible contact. Gotta look close, using a magnifying glass...