Pamco coil high ohmage

[sid693]

I have been messing with my bike for a little bit. Originally I was thinking the bike was running too lean and finally got around to checking the coil after 5twins gave me a plethora of information. The bike has strong hesitation around 3/4 to full throttle as of there is a revolutionary limiter. I read out the coils the other day after I found out I had a pamco with pma. I am got the bike as is and has ran fine for some time. Info on the bike. It's a 79 running 30 pilots. Needle at 3rd notch 140 mains. My coil is reading 5.1 to 5.3 ohm and when I first hook up the leads it trickles down from around 6 or 7. I read infinity as expected between terminal and lead and terminal and post. I read 25000 between plug wires. I am thinking my coil cropped out and could be the reason for my hesitation. Is there anything else I should check out before jumping to this conclusion

 

[retiredgentleman]

From the Pamco web site....................coil primary 2.5 to 4.5 ohms; from one plug to other plug terminal 15K to 20K ohms. Which ignition coil do you have..............do you know what brand it is?

Does the Pamco still use the mechanical advance fly-weights, or do you have the E-advancer option? If you have the mechanical advance, make sure that the fly-weights move freely. Open them by hand, and they should snap back smartly to closed when released.

Since you have a PMA, you should measure the battery voltage at idle, at 3000 rpm and at 4000 rpm.

 

[pamcopete]

PAMCO does not manufacture or sell ignition coils.

 

[TwoManyXS1Bs]

... I read 25000 between plug wires...

Is that including 5k resistor plug caps?

 

[sid693]

From the Pamco web site....................coil primary 2.5 to 4.5 ohms; from one plug to other plug terminal 15K to 20K ohms. Which ignition coil do you have..............do you know what brand it is?

Does the Pamco still use the mechanical advance fly-weights, or do you have the E-advancer option? If you have the mechanical advance, make sure that the fly-weights move freely. Open them by hand, and they should snap back smartly to closed when released.

Since you have a PMA, you should measure the battery voltage at idle, at 3000 rpm and at 4000 rpm.

I have the weights. When I rotate the advancer forward it opens up the fly weightd. All moves freely and weights snap back as intended with springs. As for the ignition coils I am assuming it is whatever one came with the kit or scavenged. I am not sure how many people have had this bike prior to me but I contacted 3 owners back and he didn't even know he had a pamco. As far as I know from reading out my coils is that they are out of tolerance.

 

[sid693]

Is that including 5k resistor plug caps?

I am not sure. I read plug end to plug end. If there is a 5k resistor installed I am unaware of it.

 

[sid693]

PAMCO does not manufacture or sell ignition coils.

I figured you didn't given that everything point to mikes for the coils. Just trying to diagnose my bike the best I can. Thanks for chiming in.

 

[retiredgentleman]

Measure the battery voltage, as you rev the engine to 4000 rpm. It should go up to about 14 to 14.5 if all is normal (not higher and not lower).
Assuming you have the stock BS38 carbs, I suggest you go back to the stock main jet #135, unless you have open exhausts with no restriction.
Check that your carb rubber diaphrams have no holes in them. If they have small holes, then the slides will be unable to lift fully.
Use a timing light to confirm that it moves to full advance as you rev the engine to 4000 rpm.

Ignition coil suspect.................maybe. I suggest you make a visual check of your spark. Make up a test spark plug as shown in my picture. This test will be done inside a dark garage. Use a cooling fan blowing on the engine. Start and warm up the engine. Adjust the idle for around 1500 rpm. Shut off the engine. Disconnect one spark plug lead and connect it to the test plug. Ground the test plug by clipping the alligator clip to an engine cooling fin. Start the engine , and let it idle on one cylinder. You can then view the spark on the test plug. It should be a fat blue spark, not a wimpy yellow spark.

 

[sid693]

Measure the battery voltage, as you rev the engine to 4000 rpm. It should go up to about 14 to 14.5 if all is normal (not higher and not lower).
Assuming you have the stock BS38 carbs, I suggest you go back to the stock main jet #135, unless you have open exhausts with no restriction.
Check that your carb rubber diaphrams have no holes in them. If they have small holes, then the slides will be unable to lift fully.
Use a timing light to confirm that it moves to full advance as you rev the engine to 4000 rpm.

Ignition coil suspect.................maybe. I suggest you make a visual check of your spark. Make up a test spark plug as shown in my picture. This test will be done inside a dark garage. Use a cooling fan blowing on the engine. Start and warm up the engine. Adjust the idle for around 1500 rpm. Shut off the engine. Disconnect one spark plug lead and connect it to the test plug. Ground the test plug by clipping the alligator clip to an engine cooling fin. Start the engine , and let it idle on one cylinder. You can then view the spark on the test plug. It should be a fat blue spark, not a wimpy yellow spark.

Thanks sir. I will give that a check. I am running open exhaust with pod filter. I originally had the bike dialed in perfect then lost a mix screw and started playing with everything and all went to hell. I have since replaced my rubber carb diaphragms and replaced the mix screw. As of now the bike idles fine and runs fine up to 3/4 throttle. Once I go full it misfires/backfires/hesitates. I am going to look into the advance to be sure my mechanical advancer is moving as advertised as well as check the spark with the high tech mechanism that is pictured. Thanks for the input. It is getting my hamster wheel spinning again.

 

[retiredgentleman]

Once you go to open exhausts and pod filters, you're in uncharted territory. I can't help you on that, as I use the stock air box and stock exhaust. You are 2 steps up on the main jets, which may or may not be correct. It involves trying smaller and larger jets until you find the right size.You may be lucky and get 5twins involved.....................he's our carb guy on the site.

 

[sid693]

Once you go to open exhausts and pod filters, you're in uncharted territory. I can't help you on that, as I use the stock air box and stock exhaust. You are 2 steps up on the main jets, which may or may not be correct. It involves trying smaller and larger jets until you find the right size.You may be lucky and get 5twins involved.....................he's our carb guy on the site.

I spoke with 5twins already. Only reason I made a new post was because of the high ohmage on my coil. Seemed odd that it was out of tolerance according to the pamco troubleshooting guide. You guys shared a good bit of information for me to go off of. I will regroup and form a new plan as to what I need to replace/tweak. Thankso retired gentleman

 

[pamcopete]

side693,

Most Ohmmeters have difficulty reading low ohms. Sometimes this is due to a bad battery in the Ohmmeter, sometimes it is because the test leads sold with a lot of inexpensive meters introduce resistance. In any event, you have to account for the intrinsic resistance of the meter and the test leads. You do this by touching the leads together and reading the Ohms. Typically, this will be about .3 Ohms.Subtract that from whatever you read for the primary of your coil. Also, a hot coil will read higher than a cold coil. The resistance increases with temperature, so if you started with a reading of, say, 6 Ohms and saw it trickle down to 5 as the coil cooled, that could be temperature related.Better still, do the following:
1. New battery in the meter.
2. New test leads that are better quality than the leads that came with the meter.
3. Measure a known good device that has the same Ohms as you expect from the coil.
4. Disconnect all associated wiring from the coil when reading its resistance.

 

[sid693]

side693,

Most Ohmmeters have difficulty reading low ohms. Sometimes this is due to a bad battery in the Ohmmeter, sometimes it is because the test leads sold with a lot of inexpensive meters introduce resistance. In any event, you have to account for the intrinsic resistance of the meter and the test leads. You do this by touching the leads together and reading the Ohms. Typically, this will be about .3 Ohms.Subtract that from whatever you read for the primary of your coil. Also, a hot coil will read higher than a cold coil. The resistance increases with temperature, so if you started with a reading of, say, 6 Ohms and saw it trickle down to 5 as the coil cooled, that could be temperature related.Better still, do the following:
1. New battery in the meter.
2. New test leads that are better quality than the leads that came with the meter.
3. Measure a known good device that has the same Ohms as you expect from the coil.
4. Disconnect all associated wiring from the coil when reading its resistance.

Thanks pete. I will chalk it up as possible bad reading and dig intout it a little better. Thanks for all the support. I will give you all and update when I get back into it. Got work the next 2 days then 3 days of tinkering.