Jim's 1980 SG Miss September

Also, if you have the original rotor, it’s going to short sooner or later. It would be nice to be able to turn off that current drain. Of course, once this modification is done, you’ll never need it.
 
Reduce energy required for engine cranking. Save 4 or 5 amps that the rotor draws and it also should make engine easier to turn.
Jim
It would be interesting to know the difference in amp draw and cranking speed between the rotor being energized and not being energized.

Ahhh....yeah, I sort of thought that too...

Yeah, reduced cranking current draw - yup.

Good one Jim.
 
Is the juice worth the squeeze.
By that I mean you're adding components and complexity to the bike. Remember KISS.
Well, I guess that will depend on the data and the individual who chooses to use it. A SPDT relay is tried and proven. You can't throw a cat inside a modern car without hittin' one. On the KISS scale, it's a pretty simple, reliable device.
 
On the KISS scale, it's a pretty simple, reliable device.
True
It still adds complexity and a unnecessary device. Since you understand it it is no problem.
 
Not saying it's a bad thing to do. Just more components more potential for problems.
 
A cruise control is an "unnecessary device." But given the choice, I'd rather have one regardless of the complexity.
We'll see what the data shows as far as the usefulness of this mod, but at the end of the day... it's my bike. I get to decide what overly complex means. ;)
 
Yeah seen some interesting threads when the electrons go silent on modern bikes. Bunch of smoke n mirrors.
Data Mr. Holmes I need Data!
Holmes_and_Watson.jpg
 
A cruise control is an "unnecessary device." But given the choice, I'd rather have one regardless of the complexity.
We'll see what the data shows as far as the usefulness of this mod, but at the end of the day... it's my bike. I get to decide what overly complex means

Good for you, Jim! The creativity on this forum between members is what makes it such a great place to hang out. Will be very interested to see the details of a) parts used w/ configuration/setup/installation, and b) net end results. Could be a real safety thing to have on longer trips. Hey, not to hijack this thread or derail it in any way, but speakin of cruise control ..... I was wonderin. What is the best throttle lock to use on these XS650's?
 
I use a Cramp Buster (about $8.95 at any H-D shop - right next to the kidney belts, ear plugs and Metamucil) and a Go Cruise thingy which costs around $30 or so I think.

I like the Cramp Buster because it simply relieves my hand (NO jokes you guys - NONE!) and the Go Cruise is good on longer stretches because you can simply set it and if a hill comes along, open up a little to maintain speed and then let go again to return the original speed. When you need to really slow down, you just roll-off in the usual way. The combo works well for me.
71vAB33g6PL._SY355_.jpg
go-cruise-2-aluminum-universal-motorcycle-throttle-lock-cruise-control-by-2wheelride-18.gif
 
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Years ago I drag raced my street bike at the local 1/8 mile bracket races. I noticed all the Kaw. 900's and so on had removed their alternator rotor and used remote starters. So one day I pulled the rotor from my 82 Honda 750 Nighthawk and went for a short ride., When launched hard it REALLY improved acceleration! I always rode mine to the strip so leaving it off was not gonna happen, but I got a machinist buddy turn some metal off the backside of the rotor to reduce weight about a pound and a half. That helped a lot so I added a toggle switch inline with one of the wires going to the brushes which de-activated the magnetic drag on the crank. Only a small, if any, gain but hundredths of a second count! Always ran without headlight off too, another toggle switch, mounted in headlight shell and wired to low beam accomplished that.
 
Well, here's the formula:

1 HP = 746 watts
- so, 4 amps at 12 volts is about 48-50 watts which is nearly 1/10 of a HP.

I guess that might make a difference, but I suspect that reducing the flywheel mass of the rotor may have made more of a difference in getting the engine to rev-up more quickly.

In terms of the draw while the bike is starting, I agree that the 4-5 amps of the field (if that is the correct number) might help - much in the same way as the headlight goes off when you hit the starter button on most bikes.
 
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