Ignition system

[TallBob]

I just purchased a engine (4R0 prefix) from what I understand was a 81 XS1100SH. The engine appears to be in really nice shape but is missing the entire left side ignition components and cover. There is nothing there but the tapered end of the crankshaft.
My question is, can I swap all the ignition components from the 79 engine that this 81 engine is going to replace in my 79 Standard and be good to go? Also,will the 79 carbs work on the 81 engine? Thanks much

[motoman]

I just purchased a engine (4R0 prefix) from what I understand was a 81 XS1100SH. The engine appears to be in really nice shape but is missing the entire left side ignition components and cover. There is nothing there but the tapered end of the crankshaft.
My question is, can I swap all the ignition components from the 79 engine that this 81 engine is going to replace in my 79 Standard and be good to go? Also,will the 79 carbs work on the 81 engine? Thanks much

Carbs transferred over are not an issue, just use 78-78 float settings for those early carbs. Also, will need to use the same 2H7 ignition module to go with the ignition components your planning on installing from the 79. The earlier ignition assembly use centrifical advance along with the vacuum advance. The centrifical advance is accomplished thru ignition module(TCI) on the 81 models and 82 Maxims(thru 84 Maxims in Canada).

[TopCatGr58]

Hey there Bob,

You will need to also put on a 78-80 2H7 series TCI unit to work with the mechanical timing parts. The timing curves are a bit different/more advanced with the 78-79's and closer to the engine specs with the 80, so it would probably be best to find an 80 set of timing parts to transplant, but the TCI can be from any 78-80 year model.

IF you have the 81 TCI and want to keep/use it, then you will need to get the 81 parts because the 81 has the cent. adv. curves programmed into the TCI, that's why it doesn't need the centrifugal mechanical adv. parts, just the vac. pot.

The 81 also uses the newer(but still 30+ y/o coils) 3 ohm style, and so no ballast resistor is needed, so even though you get a 78-80 ignition parts, you will just need to use 3 ohm coils so that the 78-80 TCI still sees 3 ohms resistance on that part of the circuit. If you don't have the OEM coils, then you will want to look into getting some hi output 3 ohm coils, either Dynatek or Accel.

T.C.

[TopCatGr58]

Forgot, aside from the 79 carbs as Brant/Motoman said is okay, provided you use the specs for the 79 carbs....float heights, and jet sizes, don't use the 81 carb specs, they are for different designed carbs.

T.C.

[Ranger_xs1100]

Hey there Bob,

You will need to also put on a 78-80 2H7 series TCI unit to work with the mechanical timing parts. The timing curves are a bit different/more advanced with the 78-79's and closer to the engine specs with the 80, so it would probably be best to find an 80 set of timing parts to transplant, but the TCI can be from any 78-80 year model.

IF you have the 81 TCI and want to keep/use it, then you will need to get the 81 parts because the 81 has the cent. adv. curves programmed into the TCI, that's why it doesn't need the centrifugal mechanical adv. parts, just the vac. pot.

The 81 also uses the newer(but still 30+ y/o coils) 3 ohm style, and so no ballast resistor is needed, so even though you get a 78-80 ignition parts, you will just need to use 3 ohm coils so that the 78-80 TCI still sees 3 ohms resistance on that part of the circuit. If you don't have the OEM coils, then you will want to look into getting some hi output 3 ohm coils, either Dynatek or Accel.

T.C.

Hello TallBob,

As T.C. stated:

The timing curves are a bit different/more advanced with the 78-79's and closer to the engine specs with the 80, so it would probably be best to find an 80 set of timing parts to transplant, but the TCI can be from any 78-80 year model.

If after you get this all sorted out and you find that you want the 80 timing parts or TCI...PM me...I'm only about 30 miles away from you.

[TallBob]

Thank you to all you guys for such a fast response. Whenever I go to start installing the ignition, do I need any special tools to do this. As I mentioned earlier,all that is on the ignition side of this motor is the protruding tapered end of the crankshaft , and it has a black colored collar of some kind near the end with a small tab on it? Not sure how all of what has to be assembled or if any special pullers or flywheel presses for lack of a better description are needed?
Ranger, I will PM you to discuss about the parts you mentioned. Again,thanks to all!

[Ranger_xs1100]

Thank you to all you guys for such a fast response. Whenever I go to start installing the ignition, do I need any special tools to do this. As I mentioned earlier,all that is on the ignition side of this motor is the protruding tapered end of the crankshaft , and it has a black colored collar of some kind near the end with a small tab on it? Not sure how all of what has to be assembled or if any special pullers or flywheel presses for lack of a better description are needed?
Ranger, I will PM you to discuss about the parts you mentioned. Again,thanks to all!

No problem Bob,
I have a complete SG motor here that we can take apart!
You can take home whatever you need and you'll know how to put it all back together again!

[TallBob]

Bob,
I just might take you up on that offer!
Thanks