Alternator disconect | GTAMotorcycle.com

Alternator disconect

dirtbag

Well-known member
I have a 1980 GL1100 (goldwing) that I stripped and have been taking to the St Thomas 1/4 mile. (12.67 @ 105mph)

A friend suggested I could gain some power by disconnecting the plug to the alternator. The thought being their would not be magnetic opposition to it turning.

Rather than fiddle with unplugging the connector before and after a pass I would like to add a toggle switch. Is it possible to switch off "power" going to the unit? The connector has 3 yellow wires but I thought maybe they are powered somewhere from a single source. My other option is to add 3 toggles switches - I'd rather just flick 3 toggles than fiddle with the plug. If I went that way would there be a problem flicking those switches one at a time with the bike running? Or would it be best to do that with the bike off?

Any help appreciated.
 
shouldnt be a problem flicking it off with the bike running. just remember that the moment you flick it off you're running purely on your battery source
 
How about a three pole relay?
...by disconnecting those three wires you are not disconnecting the alternator, you are just eliminating the path for the generated electricity, the alternator will still drag (the alternator is a permanent magnet design) ... and generate electricity, that HAS to go somewhere. Bike alternators are not the same design as car alternators.

Still running the stock alternator?
If this is a dedicated drag racer why not toss the alternator all together and run dead loss... or splice on an auto alternator with a belt going to the timing belt cog... that way you remove the belt, simple it's right in front of the motor, and remove all that dead rotating mass. I've done this to a couple of 'wings.

What are you doing for rear gears? 12.65 @ 105 needs help off the line... no?
 
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Yes this is a dedicated race bike but I'm not dedicated to it enough to start changing out the alternator. Installing 3 switches seemed like enough effort for what I might gain.

Not sure I understand the question about the gearing. Currently it has the stock gearing and again I'm only in it for fun so I won't be changing gears either.

Thanks
 
How about a three pole relay?
...by disconnecting those three wires you are not disconnecting the alternator, you are just eliminating the path for the generated electricity, the alternator will still drag (the alternator is a permanent magnet design) ... and generate electricity, that HAS to go somewhere. Bike alternators are not the same design as car alternators.

Still running the stock alternator?
If this is a dedicated drag racer why not toss the alternator all together and run dead loss... or splice on an auto alternator with a belt going to the timing belt cog... that way you remove the belt, simple it's right in front of the motor, and remove all that dead rotating mass. I've done this to a couple of 'wings.

What are you doing for rear gears? 12.65 @ 105 needs help off the line... no?


This is true. you'll gain nothing by creating a disconnect switch. All you're doing is adding extra grams of weight (switch).
 
Yes this is a dedicated race bike but I'm not dedicated to it enough to start changing out the alternator. Installing 3 switches seemed like enough effort for what I might gain.

Not sure I understand the question about the gearing. Currently it has the stock gearing and again I'm only in it for fun so I won't be changing gears either.

Thanks

Why I ask the question about the gearing is I once thought of drag racing a GL1100, but found there was no aftermarket gearing available... so I would end up running a 14-15" rear wheel to get the final gear ratio to get the pig out of the hole. It didn't happen.
 
As mentioned before, I believe there is no significant gains by creating a disconnect switch. Because the engine is still turning the alternator in a magnetic field. The coils running in the path of the magnetic field creates the resistance. You would have to physically disconnect the alternator from the engine
 
Why I ask the question about the gearing is I once thought of drag racing a GL1100, but found there was no aftermarket gearing available... so I would end up running a 14-15" rear wheel to get the final gear ratio to get the pig out of the hole. It didn't happen.

Seems to launch OK. I'm often a respectable way down the track before the fast bikes pass me. They have to slow down to get the front wheel back on the ground but that's never a concern for the wing.
 
Your bike has the typical 3 phase shunt type regulator. (Later GoldWings have automotive style alternators). The shunt type regulator means that no matter what the electrical load, the alternator will always produce maximum output with whatever excess created shunted (shorted) by the regulator. Disconnecting the yellow stator wires will reduce the rotational load on the engine as no electrical power will be produced (or shunted). It won't be a great deal of power, possibly 1 HP.

You don't need to disconnect all 3 wires, any 2 will do the trick. Something to keep in mind; while those wires are quite light (~ #14 AWG) they carry a lot of current for the size (~ 30 Amps), any switch you use will need to be able to carry this current while turned ON.
 
This is true. you'll gain nothing by creating a disconnect switch. All you're doing is adding extra grams of weight (switch).

In fact that is not true. By disconecting the wires you still have voltage but no current so there is some savings to be had - not much but some.
 
In fact that is not true. By disconecting the wires you still have voltage but no current so there is some savings to be had - not much but some.

Power=voltage*current. If current goes to 0 (which it has too if there is no circuit), power goes to 0. There will obviously still be some mechanical losses, but no longer any electrical losses.

It looks like the alternator only makes 300 watts so that is all this mod should be worth, less than 0.5hp (maybe up to one if you stopped it spinning). But every bit counts at the track, have fun.

Another vote here for removing the charging system entirely on a drag bike. I've run for over an hour on battery alone when my charging system failed on a CB450SC, you should have lots for a day of racing.
 

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