Swapping out a motor

[DGXSER]

Excellent question Ivan. I have yet to get my pea brain wrapped around the resistor issue in the ignition system.

On one hand it seems it is referred to as only keeping radios from getting interference. On the other it seems like an issue that could kill the TCI or some coils

I am no sparky for sure, so the only thing I know is resistor resist the flow of electricity, like a built in electrical dam. I have read about it being in the plug caps, and about a resistor on the frame. Seems I have some electrical info to kick around.

[TopCatGr58]

Okay,

The ballast resistor is to protect the older style OEM 1.5 ohm coils from overheating, it takes the 12 volts and drops it to about 9 volts while the engine is running. During startup, the TCI redirects the current to the coils bypassing the resistor to give them full 12 volts for easier stronger starting, but once it's running, the TCI then sends the power to the ballast resistor circuit to protect the coils. The total resistance load on that wire for the TCI is ~3 ohms, 1.5 for coils, and 1.5 for ballast resistor.

However, I just reviewed the PINOUT for the 81TCI, and it only has 1 Red/White wire sending power to the 81 3 ohm COILS vs. the 2H7 TCI that has 2 RED/WHITE wires, one going directly to the 1.5 ohm coils and 1 going to the ballast resistor side of the coils.

So....looks like it might not be as plug and play as thought!? I haven't looked for/found the EXACT PINOUT diagram for the 81 vs. the 80 TCI, so I can't tell you for sure where the RED/WHITE connector is on the TCI, but there will be 2 of them in your harness and connector for the 2H7 80 TCI. You would need to take a test/ohmeter and check each RED/WHITE wire in the TCI plug and see which one gives you no or very little resistance to the RED/WHITE wire at the ignition coils, that would be the NON-Resistor line. Then find the corresponding terminal for the 81 TCI, hopefully you still have the 81 Harness to check the wiring connector so you can determine which prong is for the Ignition coil RED/WHITE wire. Then make sure that the OTHER RED/WHITE wire on the 80 harness/connector which should be the resistor wire is the one that goes to the prong for the RED/WHITE wire on the 81 TCI!

The 81 TCI RED/WHITE wire/prong needs to see 3 ohms on that wire, so that's why you don't want to use the 80 harness RED/WHITE wire that goes directly to the coils, it will only provide 1.5 ohms which can draw too much thru the TCI possibly burning it up, along with burning up the coils because they will be getting 12 volts all the time!

Good Luck! I'll see if I can find the actual pinouts for the 81 and the 80 to help determine IF the RED/WHITE wires of the 80 harness will plug into the correct prongs of the 81 TCI!?
T.C.

[DGXSER]

OK TC.....I said PEA brain...Small.. It will take several reads and a diagram or two for me to get that one straight.

Suddenly, changing out the timing assembly seems MUCH simpler and easier!! And heck of alot less risky to boot.

[latexeses]

DGXSER,

I'm with you. That looks like the word version of the old "shell" game. At least a three read post. Maybe someday electricity won't look like magic to me.

[DGXSER]

Ok..so the 81 has only one red/white wire form the TCI that goes through a resistor to the coils, never eliminates it for that stronger starting current. While the older style used two red white wires, one bypassing the resistor for starting and one going through for normal run operation.

Interestingly enough, the wirign diagram in my clymers is identical for an 80 or 81 ( same diagram titled for both years).

[TopCatGr58]

Hey DG,

The 81 doesn't use a resistor, it sends all 12 volts directly to the 3 ohm coils, it doesn't use the 1.5 ohm coils, that's why it doesn't need a resistor in line. Yeah, Clymer's has a few errors, even the XS/XJ Cdrom has the same wiring diagram for the 80 and 81 specials, but they are different.

If you go to the LINKs section, a few pages deep, you'll find the XS owner's Manual for the 81H/SH that I posted a while back, includes the OEM wiring diagram, black and white, but you can still follow the wires, it's in PDF format, can rotate and blow it up to see it. The whole file is about 6 MB for download from my ISP's webspace!
T.C.

[PMG58501]

Okay guys....you are all truly unbelievable. Are you all electrical engineers? How do you know this stuff?

Rebuilding my current motor sounds better and better all the time.

Peter

[DGXSER]

Very good info TC. So that would tell me I can not swap coils on my 81 with those from a 78-80.

PMG, I would just swap out the timing setup to keep it the same. I have not done it myself, but saw another member here do it in quick order. For us uninitiated novices, probably take 3-4 hours at most. Much easier than rebuilding.

[PMG58501]

Okay boys.....you've talked me into it...I'll swap out the motors.

Next question then, how do I pull the timing setup from the 80 engine and swap it into the 81 engine? Is it something I should be able to find a link to among the threads?

Peter

[Bigfoot]

Am I missing something? Why couldn't he just swap the coils as well?

[DiverRay]

Am I missing something? Why couldn't he just swap the coils as well?

The pick up coils, as well as the HT coils, and wire harness are all different. It's easier to just swap the pick up coil assembly.

[oldnortonrider]

Hey DG,

The 81 doesn't use a resistor, it sends all 12 volts directly to the 3 ohm coils, it doesn't use the 1.5 ohm coils, that's why it doesn't need a resistor in line. Yeah, Clymer's has a few errors, even the XS/XJ Cdrom has the same wiring diagram for the 80 and 81 specials, but they are different.

If you go to the LINKs section, a few pages deep, you'll find the XS owner's Manual for the 81H/SH that I posted a while back, includes the OEM wiring diagram, black and white, but you can still follow the wires, it's in PDF format, can rotate and blow it up to see it. The whole file is about 6 MB for download from my ISP's webspace!
T.C.

TC; I cain't find that "81 wiring diagram/schematic". Went to LINKs section............9 links listed............???????

[TopCatGr58]

Hey NortonRider,

Here's the thread for the manual:
http://www.xs11.com/forum/showthread.php?t=1174

Right click and Downloade/Save AS the manual, then you can open it, and go to the last pages, the wiring diagram is there. If you are using a newer version of PDF viewer, then you can ROTATE the image as well as zoom in and such!
T.C.

[oldnortonrider]

Hey; TopCat; thanks!