Here is a suggested replacement for the rectifier on 1970 to 1979 XS650's. Go to Radio Shack and buy 2 #276 - 1185 Full Wave Bridge Rectifiers for $3.29 ea.. Wire and mount them as follows:
1. Fabricate an aluminum plate approx 3 X 2 inches. Use .125 aluminum. This is the heat sink. 2. Mount the Rectifiers per the drawing, using heat sink compound between the bottom of the rectifiers and the plate. 3. Solder wires per the diagram. 4. Recommend that you eliminate the plug and connector as they are toast and you have to solder anyway. 5. Solder the wires from the Rectifiers per the diagram to the existing white wires going to the Alternator and plus / minus (Red / Black). 6. Use a heat sink when soldering the wires to the rectifiers. 7. Mount this assembly in the same place as the original, using either the center hole (as shown) or one of the mounting holes for one of the rectifiers. 8. Note: Do not ground the black wire on the mounting screws. The battery box is floating, it is not a ground.
The Radio Shack rectifier is rated at 25 amps. Two of the three white wires go to one rectifier and the other one goes to the other rectifier, so about 10 amps max is going through one rectifier at full load, with the remainder, 5 amps, going through the other.
The "N/C" terminal can be used as a spare in case one of the diodes shorts out in the future. You could "pre solder" a short wire to it so if you have to use it you can just cut and splice the affected white wire to it.....don't even need a soldering iron!
Life is simple: Ride. Enjoy.
Last Edit: Aug 28, 2011 16:02:53 GMT -5 by pamcopete
I've been using the rectifier replacement for about 8 years. The Radio Shack rectifier is rated at 25 Amps. The way they are wired, there is only 10 Amps going through one and 5 through the other at full load. However, just like the originals, it is important to mount them properly with the heat sink as I described and use heat sink compound (also available from RS)between the bottom of the rectifier and the heat sink.
wow i did this last night and my bike charges again!!!! i had to buy the rest of the stuff so it cost me a lil bit more than 6.58 but i could make 10 more for that price.... i think im gonna make another one but make it a little bit nicer and have it encased i just threw the other one together to see if that was my problem plus i dont solder to well so ill be a little better the next one i hope thankls man..
That's great! Glad it worked for you.. ...however.....do not encase it ... ..that will cause a heat build up that will shorten the life of the rectifiers.. ...just let it hang in the breeze. ;D Also, when soldering, don't spend a lot of time on each contact.. ..in fact, you should go to Radio Shack and get some "heat sink tweezers" to grip the contacts when you are soldering and absorb the heat from the soldering iron.
Last Edit: May 2, 2007 11:53:36 GMT -5 by pamcopete
i got a little kit and it came with the heatsink so that was good but i still think im gonna remake it anywayss with color coded wires and plugs jsut for ease and have it a little cleaner... i dont know about my heat sink though my dad has rolls of aluminum for wrappping windows sills and all that other fuin stuyff and thats what i used.... i dont know if its right... but when i ride i can hear it flapping and its kinda annoying..... so what if i encased it to hide the wires but put in vertical slots so there is plenty of air flow"? or just leave it the way it is?
Well, I can't advise you on the "vertical slots" idea.. ...it will work initially, but may cause one of the diodes in the rectifier to short out sooner rather than later. As far as the heat sink material, you need to use a piece of aluminum as I described, about an 1/8 in thick and absolutely flat so that the metal on the bottom of the rectifiers makes good contact. Of course, you could also use a "finned" alluminum heat sink that is large enough to accomodate both rectifiers, but that will double the cost, but it might also double the life. If you want a better idea of what I'm talking about, just put your finger on one of the rectifiers after it has run for about 5 minutes... ..Ouch!...that heat is normal, but it must be dissipated by a good heat sink.
Another feature of this setup is that you have a spare pair of diodes available with the contact labeled "N/C". If you're on the road some day and one of the diodes shorts out , just move the white wire from the contact with the shorted diode and connect it to the "N/C" terminal and keep riding! You could even pre solder a short piece of wire to the "N/C" terminal now so if you ever have to use the spare diodes, you wouldn't need a soldering iron.
Last Edit: May 2, 2007 13:22:06 GMT -5 by pamcopete
For the Canuck dudes, the Source which took over Radio Shack up here still carries some of these FWBRs under the RS part number 2761185. I picked up 2 today. They are $4.99 in beaver bucks and of course we have the dreaded GST/PST to deal with ($1.40).
So overall not as cheap as the original US version but still a good buy if you look at the cost of Yammie replacement.
One thing to note: the Source guy told me they are starting to phase this stuff out so your local store may or may not have them or can get them in the future.
Cheers all, Spyug.
78 Street Tracker " Wee Beastie" Gone to a new home 83 Suzuki GS750E, " Black Booty" 82 GSX 750SZ Katana, "Wee Beastie II"
pamcopete asked me to post this here from a different thread.
I made a copy of his rectifier unit as posted above. Here's a picture:
I made my heat sink 4"x2"1/8". Due to the configuration of the standoff on the battery box, I wanted a little room between the individual rectifiers's mounting hardware on the opposite side of the heat sink (not shown in picture).
I ended up getting my aluminum from a True Value hardware store. The SKU number is 608091. It's 1/8"x2"x3feet and cost me $11.99 It's made by SteelWorks with a number of 6220. The barcode on it is 5353856220.
Also when mounting the rectifiers to the heatsink, I used lock washers, and 2 nuts locked together to insure that they do not vibrate loose. Make sure they are not too tight, you dont want to crush the rectifiers!
When soldering the connections to the rectifiers, make sure to use a clip on heatsink. Place it between the solder joint and the rectifier. Radio shack has a small aluminum clip on one, or you can use CLEAN needle nose pliers with rubber bands around the handles.
The key to have a neat looking job after you get done is to make the connection of the copper wires to the solder terminals sercure, with as little wire as possible, and as little bulkiness as possible. Also make sure you use BIG enough heat shrink tubing, If you have to "shove" the tubing on the connector it's TOO tight. Either use less wire or bigger tubing.
Also dont forget to use heat sink grease when mounting the rectifiers to the heat sink. If you dont know where to get it, any heat sink grease made for Penitum 4 CPU's found at a computer store or repair shop should be fine. Also, make sure the mating surfaces are CLEAN. Mount the rectifiers to the aluminum before soldering to help sink away heat in addition to using pliers/clip on heat sink.
I don't have a picture of the rectifier mounted to the battery box because i didn't feel like removing the battery box from the bike
Last Edit: May 12, 2007 21:40:25 GMT -5 by moya034
One more tip with the soldering of these connections.
They are fairly big, and for the purposes of the rectifier, I chose to use 14 gauge wire, which may seem like overkill.
As we all know,to solder properly, the joint, not the iron must be what actually melts the solder.
To accomplish this without burning up your diodes, you actually have to use a higher wattage iron/soldering gun. I personally prefer about 100 watts or so for this type of connection.
That kind of high wattage may seem counterintuitive to not burning up the diodes, but with the high wattage it takes very little time to heat the metal up to the melting point of the solder, only a couple seconds. Then you're done and your clip on heat sink dissipates the heat very fast. After your done the diodes never even had a chance to get too hot. (same goes for the insulation on the wire)
It's like cooking a good fillet mignon, you need really high heat to cook it so fast it doesn't have enough time to get tough.
That being said, you don't want to use your oxy-acetylene torch
If you can't make a good joint in the time span of about 4-5 seconds practice a little with the right wattage before soldering the diodes.
Last Edit: May 17, 2007 14:46:07 GMT -5 by moya034
I just wanted to say that I just completed this replacement and it works great. Many thanks to Pamcopete for posting this tip. I also did the $27.48 regulator replacement with the rectifier. This was super easy to do and took about 2hrs total including the soldering. I now have 13.5 volts at idle and 14.7 at high RPM's. Please check out my pics. Thanks Pamcopete and 650 Garage.
r80rt: :)This is a splendid write up, THANK YOU!!!!
Dec 26, 2015 16:54:05 GMT -5
mashermoto: What the what is this shoutbox for? Or should I shout, WHAT THE WHAT IS THIS SHOUTBOX FOR!
May 12, 2016 22:22:21 GMT -5
motormike: Good Day ...just a FYI.. Wild Cat is this Labor Day weekend. Still go'n on. A few 650's still make the scene. Various rides at different skill levels each day.. awards dinner sunday eve. BS in the park'n lot after dinner.
Aug 23, 2016 7:57:01 GMT -5
lsettle: First post in over 6 years!
Aug 28, 2016 19:45:17 GMT -5
kardon: Wow quiet here, where did they all go.
Oct 7, 2016 2:18:13 GMT -5
gggGary: XS650.com LOL
Feb 16, 2017 20:49:02 GMT -5
buell88: Anybody have any idea who built the xs650 tracker used in the Draggin Jeans Ad on Pipeburn?
May 16, 2017 16:24:09 GMT -5
joshua: The regulator/rectifier unit I got from Mikes PMA has closer hole spacing than original. Are we supposed to mill the holes to fit?
Jun 7, 2017 19:25:58 GMT -5
joshua: My bad. I found the bracket they supplied to mount the rectifier/regulator... Uh oh. How is this meant to work? Which way is it meant to mount? Looks like I have to use some spacers or something. Good instructions would be nice.
Jun 7, 2017 22:09:52 GMT -5
craig8johnson: Not sure if this is the right spot or not but oh well...
Jul 11, 2017 18:04:15 GMT -5
craig8johnson: I'm checking the charging system. I'm afraid I might have fried the last battery. With the solid state regulator (after market) what should it be charging at. The book says, I think, 15 volts. I'm hitting 17 when revved. Is that too high?
Jul 11, 2017 18:06:19 GMT -5
gggGary: Yes 17 volts is too high, about 14 volts is max, sounds like you don't have the right regulator or it's wired wrong.
Jul 13, 2017 6:54:33 GMT -5
dean: Just saying Hello, new member who is going to fix up a 79 XS650 that has seen its better days. I will definitely have lots of questions coming up.
Jun 23, 2018 16:45:32 GMT -5
tt650: Trying to breathe life into a 1980 that's been stored (indoors) for 25 yrs. Air filters are dry rotted. Have cleaned carbs but she only runs briefly on choke then stops. Need jet setting info and other ideas that might help her idle and rev.
Jul 3, 2018 19:15:19 GMT -5
trix13: Hey everyone! New to the forum and am fighting those gremlins!! New charging system, ignition switch, coil and fuse box. Resistance is higher than normal on the ignition pick up so I'm trying to find one. No such luck yet.
Aug 16, 2018 8:50:48 GMT -5
trix13: Also, even though all of my connections are clean, I cannot seem to find out why , when at higher rpms, I hit the signals and the rpms pulse with the signals...hahah. same with the brake light. I appreciate all input!!
Aug 16, 2018 8:55:08 GMT -5
bob99: how do I post a question. I am new to the forum
Jun 6, 2019 10:52:10 GMT -5
adlpc: Hello all! Been enjoying your edifying posts and discussions - and as a fan of the XS650 since my early teenage years happy that I now own a 1980 Special which I plan to turn into a vintage half faired racer. Thank you all for being here!
Oct 1, 2019 0:58:56 GMT -5
jimothyj: Hello everyone, I just joined & wish would have known about this site in 2014 when I brought my 1974 TX650A back from the grave. I have spent a good deal of $$ and alot of time on it. Just painted it and working on electrical, I will post pics soon,
Apr 10, 2021 2:14:13 GMT -5
louisvan: trix13 - I had a problem with my 1975 SX650. When I got to highway speeds, the engine lost power. The problem was in the connectors. At a certain vibration and the wind pushing on the wiring loom, the connector lost continuity. A bad crimp to the wire.
May 20, 2021 1:19:09 GMT -5