RR question on kz750ltd w/ upgraded battery

So i've upgraded to a Ballistics battery and dont want to end up with a brick. From what i understand (which isnt much) i should replace the rr with a modern unit. Is there anyway around an $80 plus unit? Suggestions?

Nope. Unless you find one used perhaps. Newer Polaris ones can be had on ebay. I could not tell you for sure what the model is. Or how to wire it. You want one that is "mosfet" technology.
The way I look at, you should only ever have to buy 1 unless you wire it wrong. The battery should last longer than a lead acid so you are really ahead. Just my .02

When you say it is recommended to install a modern voltage regulator, do you mean a fairly new one or a Mosfet type? There's a recent KZR topic by hollywoodmx in which he's installing a mosfet reg-rec.

My 81 650 came stock w the same voltage regulator/rectifier as your bike --- I installed a used one from a low mileage 2007 Ninja 500: it's virtually identical to stock, but the connector is different (easy swap)(credit to loudhvx). The Ninja & Vulcan 500s have the same reg-rec up to 2009.

If you want to get a Mosfet, you might be able to get a new one on eebbaayy. For a while they were available for ~$49 --- there was a recall, hence the replacement (Kaw part #99999-0377). Because of the recall, you need to be careful about buying used (see pdf link below). You don't necessarily have to get one from a Kawasaki --- the other Japanese bikes also used mosfets, but I do not know if there was a recall on any of those (I think Shindengen is the only company that makes voltage regulators for the Big 4).

www-odi.nhtsa.dot.gov/acms/cs/jaxrs/down...CRIT-12V064-9756.pdf

The Shindengen SH-775 is a series type R/R, which differs from the typical shunting R/R in that it will not stress your stator by dumping unused current back to the stator, thus overheating it in the process. Polaris used these on some of their atv units, Polaris part #4012941, and you can buy one brand new for about $70. Triumph sells them as part of a retrofit kit on bikes that are eating stators and offers this nifty harness kit...Triumph Part Number is T2500676. Compufire also sells a nice Series type R/R, but they cost more than double the Shindengen. Either way a Series R/R is a nobrainer if you want to make sure your charging system is reliable.

Mosfet technology has been around for decades. I believe it wasn't used on bike reg/recs until recently because they are more prone to failure than the old fashioned diode/SCR shunt.

My buddy has gone through a couple on his Honda. They went up in smoke. He got another one with more heat-sink area and he added some vents to the body work to cool it, and it's been working ok.

The Shindengen FH-009/12/14 MOSFET R/R are some of the best units available, other than the series SH-775 type.

I ended up buying a mosfet regulator from an 07-08 cbr600rr. Not something i'll notice but wiring was straight forward and everything works fine.

3rd year with a Lithium Iron battery and stock 78-80 regulator on a 79 750 twin, and after being parked for 7 months it fired right up.


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Ya, I probably could have done the same but I probably read to many threads on Lithium batteries dying due to overcharging and blah blah so I protected myself for $50

The biggest difference between the MOSFET and the series R/Rs is heat. The MOSFET will generate much more heat in the stator because the stator continues to run full tilt. The series R/R turns the stator off, saving your stator life.
This issue has been beaten to death over on GSR so I will not repeat all the technical details. If you want to know more, just visit there and look for threads started by posplayr.

It would be very surprising to me if that were true.

koolaid_kid wrote: The biggest difference between the MOSFET and the series R/Rs is heat. The MOSFET will generate much more heat in the stator because the stator continues to run full tilt. The series R/R turns the stator off, saving your stator life.
This issue has been beaten to death over on GSR so I will not repeat all the technical details. If you want to know more, just visit there and look for threads started by posplayr.

I think you have mosfet mixed up with Thyristor (SCR). The series reg/recs use the mosfets. The shunting reg/recs use the SCRs.