Voltage Regulators

marvin

FWIW. I have been doing maint. on a friends S4RS (Testastretta Monster) She has put 4 or 5 voltage regulators in it. Last time she took it to a local Dealer and they moved the regulator to a "cooler" place.

I have the same engine and OEM regulator on my 851, also the same engine. I have put many miles on it with no problems. But my regulator is mounted down low, in the air flow, and on an aluminum plate with transfer grease between the aluminum plate and the regulator.

As Mark T (who knows much more about it than I) explained to me. The old shunt type regulators , when the battery is charged, turns that energy into heat. If that heat is not dissipated the regulator fails often times taking the battery out with it. Bottom line, heat makes them go South. So, at the very least mount your regulator with heat transfer compound between it and the mount. And or mount it on a heat sink of some sort.

The newer style regulators (MOSFET type) does something different and does not turn that excess energy into heat. If you need a new regulator I would suggest buying the MOSFET type.

PTwo

Hello Marvin!

This is good info, and is kind of making me rethink my strategy. As you know, I'm resurrecting my bike that has been sitting for 20 years. The plan was to update/fix/replace anything that might compromise reliability.

For the RR I was looking at this, as it is MOSFET and correctly wired:

I guess the question is; is the original reliable if it's kept cool, or is the design/quality the issue and it'll fail regardless?

My plan is to get my bike dialed in this year and hit WDW next year.

Best regards,
Peter

marvin

Hi Peter,

I don't know for sure. all I know is that my OEM old style has lasted for 20K miles , but it is mounted as described. So I'm assuming they are OK if mounted properly and kept cool. However if you are going to purchase a new one anyway I would opt for the MOSFET design.

Mr.R

I've gone through several reg/recs over the years, blah, blah, blah...
Always using copper slip to act as a heat transfer between the unit and the frame up behind the headstock.
But the last one I fitted was a Mosfett, that I fitted with heavier gauge wires, gold plated bullet connectors soldered to the cables, to an alloy tail tidy/reg' plate mounting plate/heat sink up under the rear of my single seat unit, with plenty of cool air flowing around it.
So far after a couple of years and a few thousand miles it's been totally reliable.
After years of chasing the problem and trying different combinations...
I think that I've finally found the solution.

Steve R

PTwo

Yes, this is what I'm starting to think I can do with the current unit. It's original, but the bike only has 11k miles on it.

I guess the big question is whether the old unit is, in fact, reliable if mounted somewhere sensible?

marvin

It should be noted that my OEM unit is the newer 3 phase unit that is OEM on a '07 S4RS, not the original 8541/888 unit.

griff851

After a reg catching fire mounted near the head stock, and the difficulty putting it out with only a litre of sprite grabbed from a nearby shop, I moved it. (Much to the WTF by the young shop girlie.)
It’s now mounted on a bracket under the battery tray. It gets lots of airflow and won’t toast anything if it flames on again. Also fitted a battery isolation switch, that saves burning your hand as you try to rip off the battery wire in the mayhem. 😁 Reg went to earth while it was on fire, but didn’t draw enough to do in the 30amp fuse. Just enough to keep igniting the regulator.
PS, don’t get sprite on your instrument foam,you can’t wash it out, really not pretty. 😁

There are some good YouTube’s that explain how standard regs work and how to test them, and how MOFSET types work.

Also this guy, he has quite a few tubes, hard to believe he actually has a masters degree. Funny bloke. https://youtu.be/sI5Ftm1-jik