minimum needed to bench test a 1200 motor

[70sbudget]

so im not to familiar with the 1200 yet but would like to bench test mine prior to install. I have a 78 that it is going into. ignition coils from a 1500 so need to figure out the wiring from these three different generations.

obviously fuel, air and spark for fire but as far as the wiring, do i need ALL OF IT? what is the bare minimum wiring to make this 1200 thing fire and run for a minute here and there?

[ericheath]

Installing the motor seems daunting, but isn’t that bad. I think you will spend as much time farting around with wiring as you would just putting it in.

[70sbudget]

motor is out, battery is out, ignition system is out as upgrading system and parts arrived so figured easier to do it out of the bike at this point.

[dontwantapickle]

power to the coils and power to the ignition is all it takes to make it spark.

[Liam]

There a few flavours of 1200 engines. 1984 had the ignition pickups at the rear. 1985 and later this moved to the front.
The easiest thing is to get the ignition unit from a GL1200 and the coils and everything just plugs in. Power it up and off you go.

1200 ignition unit.jpg (31.33 KiB) Viewed 291 times

[Liam]

This is the wiring.

1200 coil diagram.jpg (41.04 KiB) Viewed 290 times

[70sbudget]

Liam, thank you for the wiring harness. I have an 85. I have wires coming off of the motor but it doesn’t look like they plug into the green box as shown, which I also have. I’ll try and post some pictures this weekend. What does the vacuum hose on the black box connect to?

[rcmatt007]

yes they don't... they go through the wiring harness....

two things can go bad. The pick-ups (on the 85 in the area of the timing belt) and that can be one or both. Last I checked still available. or the box itself... not available, except from a another bike

[Shadowjack]

The vacuum line connects to a port on the #4 intake runner. It's not needed to test; only works in 4th and 5th. Just plug the intake port.

[70sbudget]

The vacuum line connects to a port on the #4 intake runner. It's not needed to test; only works in 4th and 5th. Just plug the intake port.

Do the 1000 carbs have this port? I will either be using a single carb conversion or the 1000 carbs. How does it identify third from fourth?

[ericheath]

There is a bundle of wires coming from transmission, one for each gear. So the box uses gear selection and vacuum for timing.

In lieu of no vacuum signal, I believe but don’t know as fact, that it will default to roughly 37 degrees, same as earlier years. If so, you will be fine without it. You’ll probably get a few more mpg if you can get them hooked up.

[70sbudget]

There is a bundle of wires coming from transmission, one for each gear. So the box uses gear selection and vacuum for timing.

In lieu of no vacuum signal, I believe but don’t know as fact, that it will default to roughly 37 degrees, same as earlier years. If so, you will be fine without it. You’ll probably get a few more mpg if you can get them hooked up.

Well my heat just went kaboom

[rcmatt007]

The vacuum line connects to a port on the #4 intake runner. It's not needed to test; only works in 4th and 5th. Just plug the intake port.

Do the 1000 carbs have this port? I will either be using a single carb conversion or the 1000 carbs. How does it identify third from fourth?

no, but there is a hose from one carb to the valve at the top front of the carbs. The 1000's do not have an ECU unit, but points which have a centrifical advance

[Shadowjack]

If the engine came from a bike with a digital dash, the neutral switch has a wire for every gear, because the gear indicator appears on the dash. Cheaper models just have the neutral, 4th, and 5th wires. Those just have an OD light on the dash in 5th.

[rcmatt007]

speaking of 1200's..... where the shift mechanism is behind the "transmission cover" (lower front of engine where the water pump and oil filter is....) there is a switch that indicates which gear. As several have mentioned, it changes the advance depending on the gear. It is easy to not think about getting into the right place when you remove the transmission cover (don't ask how I know). And DO NOT use after market gaskets for the transmission cover they are often too thin and bind up the shift mechanism.