Is it better to buy a new old stock rectifier or new replacement and why??

[butterbeats]

Hi xs400ers,
quick question; is it better to replace my rectifier with an old new stock stock or a new replacement?? and why??

thanks

http://www.ebay.com.au/itm/NEW-Yama...hash=item230b621cd2:m:mOZQ8hAkTf8dhzibs0UUtsQ



or


http://www.ebay.com/itm/REGULATOR-R...ash=item3f379064b8:g:UWcAAOxymmJTkbnV&vxp=mtr

 

[BBS360]

You've linked to two functionally different parts.
The first is a plain old rectifier.
The second one is a combo rectifier and regulator for DOHC xs400s.

The combo might be an improvement over your stock mechanical regulator but would require some rewiring to make work on your bike.

The rectification ability between the two would be exactly the same.

 

[butterbeats]

Thanks BBs360 (took your advice on the fusebox). They look similar whats the main difference?? One regulates as well?? Do I have a regulator somewhere else on the bike??

Re wiring?? How much?? The price difference is my main reason not to buy the older original rectifier ... and I assume being older might be age and wear issues even though it has not been used before.

 

[BBS360]

One regulates as well?? Do I have a regulator somewhere else on the bike??

Yes and yes.
I believe your bike should have a mechanical regulator attached to the back of the battery box.
This is the oem early style regulator: http://www.ebay.com/itm/252519371456
Later models went to an electronic regulator and the DOHC bikes went to a combination rectifier and electronic regulator.

Re wiring?? How much?? The price difference is my main reason not to buy the older original rectifier ... and I assume being older might be age and wear issues even though it has not been used before.

The older rectifier would likely work fine but that is pricey. Any three phase motorcycle rectifier could be made to work or super cheap three phase rectifiers can be found at electronics stores or ebay.
Some details here: http://www.xs400.com/threads/good-stator-or-bad-stator-proper-reading.11672/#post-120787

As for the rewiring, the connectors don't match between the combo unit and your bike. You'd need to either redo the connector on the combo or redo the regulator and rectifier connectors on the wiring harness.
Might also have to switch the field coil wires. The bikes with mechanical regulators have one wire from the field coil going to ground and the other to the regulator whereas on the SOHC bikes with electronic regulators and the DOHC bikes one wire goes to a + voltage line and the other to the regulator.

Since we're this far into it... has your rectifier failed?

 

[BBS360]

All that being said, there are combo units available that can be found with the proper separate connectors already on. Some members have used the "RR38" regulator/rectifier.
Prices vary widely on them from as low as $40-$50 from asia or over $100 from western stores but you probably wouldn't have to do any rewiring.

 

[butterbeats]

I have spent a few months trying to sort out my electrical issues. Have not taken out the rectifier as yet to test. I have fixed everything else so far and battery still dies after a few days.

The bike starts alright once the battery has been recharged.

 

[BBS360]

The rectifier test is pretty straightforward. Your meter has the diode test function that should work for it.
They don't usually fail but it is possible.

The mechanical regulators are usually adjustable. Could be as simple as turning up the regulator.
The testing and adjustment procedures are in the Haynes manual which is available in one of the manuals threads at the top of the garage.
It has the rectifier test procedure too.

 

[butterbeats]

Here is my recent fuse box bypass and what I assume is an ancient regulator attached to the back of battery holder?? I guess just by looking at it it is ready for replacement.

To test use meter while running and look for lack of life. Will check my manual for relevent voltage amounts.

I know I will want to replace it though.

 

[butterbeats]

Here is some youtube quick footage of a test on the existing rectifier. Seems to be ok??

Do you need to replace existing regulator and rectifier with the RR38 or other modern rectifier/regulators? Is states in the Ebay ad that it does both

http://www.ebay.com.au/itm/360298776930?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT