RH Coil Bad

[KJK]

She has sat for one year.

I replaced the battery and the fuel last week. Tried to start her but only heard back fires!Pulled out the choke and turned heavy on the throttle with the expected backfires. Then pulled all four plugs to check for excessive fuel. One, two, and three were wet, I may have a problem there.

Next I removed each plug one at a time plugging it back into the wire and checking for spark. Found one and four sparking!

Lifted the fuel tank and swapped the plugs between coils. Checked for spark again finding it had moved to two and three! Sure looks like a bad right coil. Checked for voltage at the ignition coil (Gray Wire) and found twelve volts all the way to the coil. Again looks like a bad right hand coil.

Is there a anything I can check be for changing this coil?

She worked great one year ago, and I'm hoping it is something small to get her running again!!

KJ
1981 XS1100
Eleven Special

[TopCatGr58]

Hey KJK,

IF you have a multimeter, you can check the Primary resistance between the 12V hot and (-) leads of the coils...not the harness, as well as the secondary windings....plug end to plug end. Also, remove the plug caps and check for corrosion where they attach to the coil wires, and also check the cap resistance.

The caps should be about 5-8K ohm, the Bare Plug wire end to ends should be about 15K ohm, the primaries should be about 2.5-3.0 ohms.

IF I understand what you did, you swapped the power/switching wires at the primary wire connectors between the coils, and the problem=no spark went from 2-3 no sparking, to 1-4 !?

If the problem switched from one coil to the other, then it's not the ignition coil, but the triggering device, either the PU coils, or the TCI!

After sitting for some time, corrosion can develop anywhere, so first you'll want to pull the connectors for the ignition system, and clean and apply dielectric grease to them. You can also check the resistance of the PU coils thru the plug at the TCI, should be about 760 ohms IIRC! The 81 has less tendency to break the PU coil wires due to less rotation and flexing of wires vs. the early models!

Sometimes, the solder joints inside the TCI where it connects to the external plugs also crack, and folks have resweated the connectors with good results! Good Luck.
T.C.

BTW, the gray or orange wires at the coils shouldn't have power when they are unplugged from the coils, just the Red/White wires. The gray and orange wires are the trigger wires that the TCI controls to break the current which causes the ignition coil magnetic field do drop and FIRE the coil. But, if the coil was plugged into the connector, and there wasn't a short, then you could find/measure voltage at the TCI on the gray or orange wire!

[KJK]

TopCat, Thanks for the help so far. Your right my trouble is not the ignition coils.

I checked the OHMs for the pick up coil at the TCI plug. I found the upper two wires read 760 OHMs as advertised, but the lower two showed 0.

I am having a lot of trouble find the pick up coil so I can check the connection and for corrosion. Is it called by another name?

KJ

[John]

The P/U coil is located under the left side (as sitting on the bike) engine cover. The one with Yamaha on it. These bikes are known to have the wires to the coils break from constant flexing. Do a search here for P/U coil wire repair, and you will find everything you need to do the repair yourse;f and save some big bucks at a dealership that won't be able to repair it anyway.

[KJK]

Can I check for continuity from the TCI plug to the pick up coil? The wires change colors somewhere in the middle. My Clymer schematic is not helping either. Am I missing something?

KJ

[KJK]

From the plug (four wire) at the TCI I read continuity through one of the pick up coils (lower). The other I do not, so worked my way toward the pick up coil checking for resistance. Did not find a beak in the wire right up to the actual pick up coil itself.

Now is there way to repair the pick up, or is it best just to replace it? Everything in side the cover is in great shape and very clean.

KJ

[TopCatGr58]

Hey KJK,

It's my understanding that the PU coils are non-serviceable. But before you jump into that, check out the tech tip about the PU coil repair, and do the tests they suggest about the wires to ensure that the wires are actually not fractured inside the insulation, which would also give you an OPEN no continuity reading.

Did you try testing the PU coil right where the wires attach to it? You might even need to strip a little bit of insulation back from it to get to the wires, and THEN if the PU coil measures badly, look into getting a replacement. Kinda pricey at about $100.00 a set NEW from Yamaha, vs. Ebay, but you're guaranteed a working part from Yamaha!
T.C.