1981 Yamaha XS 1100SH Regulator/rectifier

[davidsymons53]

Would a regulator/rectifier from an xj1100 work on a 1981 xs1100SH?

David

[DiverRay]

NO The XJ has a brush type alternator, and the XS do not. If you need a reg, check with Geezer. He builds a great NEW reg. for about $100. It has a LIFETIME warranty. that is either your life, or the bikes,

[cywelchjr]

Actually IIRC from Geezers site it says it is "his" lifetime. That he guarantees them for as long as he lives.

[Larrym]

Rectifying Issues

Would a regulator/rectifier from an xj1100 work on a 1981 xs1100SH?

David

I'm going with a "NO" also. Two different systems with two different amperages and I believe two different pin-outs in the connectors.

But I could be wrong so.....here's Geezer's WebPage:

http://www.oregonmotorcycleparts.com/Reg_rec_units.html

If you scroll down a bit you'll find pics below the "VRREM3-XS Regulator/Rectifier for the XS11, XJ1100 and all XS750 and XS850 Yamaha motorcycles."

Notice that there are two separate units:

One on the left for the XSes and the one on the right for the XJs.


I would be very surprised if they could be swapped. But I'm ok with that if Geezer agreed they could.

[clcorbin]

I've been tempted to build a microcontroller based rectifier/regulator for my bike. On my car (2005 Mustang GT), the PCM controls the field voltage directly. There is no stand alone regulator, inside the alternator or out. The nice thing is the voltage pretty much sits at 14.0 volts from idle to red line.

They did it that way to get better control over the voltage as even small changes in voltage impact the amount of fuel injected, especially at low engine speed and throttle openings. Needless to say, this was driven by emissions, not performance.

My thinking was if we could get better control over the alternator, it SHOULD allow us to keep the voltage up higher at idle. About the only real advantage would be less (possibly no) head light dimming at idle. IF the alternator can actually put out enough power at idle, of course.

One little 6 pin uC and a sprinkling of passive components could completely replace the regulator... Maybe this summer when I have more time I'll give this a try and see how it works.

[davidsymons53]

Thanks for the advice.

David

[cywelchjr]

I've been tempted to build a microcontroller based rectifier/regulator for my bike. On my car (2005 Mustang GT), the PCM controls the field voltage directly. There is no stand alone regulator, inside the alternator or out. The nice thing is the voltage pretty much sits at 14.0 volts from idle to red line.

They did it that way to get better control over the voltage as even small changes in voltage impact the amount of fuel injected, especially at low engine speed and throttle openings. Needless to say, this was driven by emissions, not performance.

My thinking was if we could get better control over the alternator, it SHOULD allow us to keep the voltage up higher at idle. About the only real advantage would be less (possibly no) head light dimming at idle. IF the alternator can actually put out enough power at idle, of course.

One little 6 pin uC and a sprinkling of passive components could completely replace the regulator... Maybe this summer when I have more time I'll give this a try and see how it works.

I believe that Geezer has already done this. His unit can't keep full voltage at idle, but it comes to full voltage much earlier than the stock unit. I believe the reason it can't do it at idle is that unlike a car, the alternator doesn't turn at a higher RPM than the engine, but at the same speed. Look at the pulleys on your car sometime, it's something around 3 to 1 ratio on them. So, if your turn 5k on an auto engine, the alternator is turning something like 3 times that.

This means that at idle, an auto alternator turns over at something like 1800 rpm for 600 at the crankshaft, which is right about where Geezers regulator hits full charging voltage.

[clcorbin]

I believe that Geezer has already done this. His unit can't keep full voltage at idle, but it comes to full voltage much earlier than the stock unit. I believe the reason it can't do it at idle is that unlike a car, the alternator doesn't turn at a higher RPM than the engine, but at the same speed. Look at the pulleys on your car sometime, it's something around 3 to 1 ratio on them. So, if your turn 5k on an auto engine, the alternator is turning something like 3 times that.

This means that at idle, an auto alternator turns over at something like 1800 rpm for 600 at the crankshaft, which is right about where Geezers regulator hits full charging voltage.

Exactly. But on the same token, the bike's alternator is designed to put out more power at lower rpm (both it's min and max rpm are much lower than a car's alternator). Needless to say "more power" is very MUCH relative!

As for using Geezer's regulator, well, where is the fun in that??? The fun in these projects is designing the part, making the PCB, building it, writing the program for it, testing it and finally putting it to work on my bike!

After several years of dealing with a super crappy garage door opener light (it used an RF signal to turn on the light, so it didn't always turn on anyway!), I finally got around to building a little interface circuit so I could detect when the garage door went up or down (by tapping into the power going to the motor itself) and then it would turn on the main garage lights (3 eight foot long high output fluorescent lights, 660watts total) for 4 minutes before turning them back on.

It works perfectly every single time and I STILL get a stupid grin on my face when I open the garage door and those big lights come on automatically and REALLY light the garage up.

But sorry, I digress....

[Geezer]

Actually IIRC from Geezers site it says it is "his" lifetime. That he guarantees them for as long as he lives.

My daughter plans to take over the biz when I retire so there's at least one more lifetime to go on these.

The XJ1100 has different plugs but works the same at the one on the XS11. Also on the XJ1100 the reg/rec has double red output wires. This was done so that one set of terminals is not transmitting all the power.

Geezer