Jim's 1980 SG Miss September

I'd like to, but it's too far gone for restoration. It's gonna be the basis for my Triumph Speed Twin tribute bike.
Kinda along the lines of this....
View attachment 111079

Hi Jim,
ooh, nice! And easy to do. Convert the frame to a hardtail, give it an Amaranth Red paint job, bolt on a Lycett saddle and she's done.
Adding a parcel rack and Triumph-style striped side badges to an XS650 Standard tank will give a look that's close enough.
Gonna use an XS650 front disk for reasonable stopping power or an earlier XS650 front drum that'll at least work better than the stock
Triumph front drum ever did?
And even if you do find one of the Triumph Sprung Hubs which were an option on that bike do NOT use it on a bike you want to ride.
Besides killing at least one mechanic who tried dismantling one without using the proper dis-assembly jig those things were deadly on the road.
 
Before I tore this bike down, the only elec. problem I had was weak charging. If I recall.... I had to rev close to 4 grand just to get a slight increase in volts. During teardown, I checked the rotor and it was about 1.5 ohms. Yup, I need a new rotor.

Fast forward to today.....
I was just gonna go all OCD on the reg/rectifier when I recalled the charging problem. So... figured it would be wise to check it also before wasting a bunch of time cleanin' up this mess....
IMG_20171224_133419.jpg


All six diodes are readin' between 300K and 400K ohms when they should read about 1 or less....

MVIMG_20171224_150657.jpg



So... I have good news/bad news scenario.... the good news is I didn't waste an hour on my OCD affliction.
The bad news... I need a new reg/rectifier. At 3-400K I'm guessin' the diode bridge is shot and all I'm reading is resistance through the regulator chip. No matter... bad is bad:(
So, here's a question for all you gents out there whose opinion I value very much... what should I do? I've a bin full of power diodes, I could easily make my own rectifier bridge... but then I gotta come up with a shunt regulator. I could buy one from Ebay and that's pretty iffy... or I could go with a PMA setup. And to be honest, if the only advantage to the PMA is you don't have to change the brushes, I ain't interested. Changing brushes is no big deal.
Sooo.... help me out here guys.... what should I do?:umm:
 
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Hi Jim,
ooh, nice! And easy to do. Convert the frame to a hardtail, give it an Amaranth Red paint job, bolt on a Lycett saddle and she's done.
Adding a parcel rack and Triumph-style striped side badges to an XS650 Standard tank will give a look that's close enough.
Gonna use an XS650 front disk for reasonable stopping power or an earlier XS650 front drum that'll at least work better than the stock
Triumph front drum ever did?
And even if you do find one of the Triumph Sprung Hubs which were an option on that bike do NOT use it on a bike you want to ride.
Besides killing at least one mechanic who tried dismantling one without using the proper dis-assembly jig those things were deadly on the road.
Hi Fred,
yeah, definitely not going with the sprung hub, even if I could find one. Not a fan of hardtails either... my backs too old. My plan is to make something along the lines of a Harley Softail. Best of both worlds.... looks like an old rigid frame... with suspension:)
 
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If those resistances were 350 Ohms then that would be about right depending on the meters characteristics. I have a deviation question for you - Are stainless Aerotight nuts suitable for securing the brace to the back brake hub?

Thank you for you view from the Aero Industry.
 
If those resistances were 350 Ohms then that would be about right depending on the meters characteristics. I have a deviation question for you - Are stainless Aerotight nuts suitable for securing the brace to the back brake hub?

Thank you for you view from the Aero Industry.
From an engineering view, a wad of dried up bubble gum on the bolt threads would suffice;)
Let me explain..... Bolts are loaded in either tension or shear... or sometimes both. The bolt holding the brace to the hub is loaded in shear only. The nuts only purpose in life is to stop the bolt from falling out.... it's unloaded.
In simple terms.....yes, that nut will work just fine Paul:)
 
Thank you Jim.

I like that OCD removal of the details on bolt heads. Depending where the bolts are located it can make a real difference aesthetically. In the past I have stuck the bolts in the lathe and trimmed the figures off, but I should have polished them. Oh well, something to revisit.
 
Please don't drink the PMA kool-aid. It's very expensive and for the most part, tastes like shit, lol. You don't need a "shunt" type regulator, that's a PMA thing and one of their weak points. They "shunt" off excess charging voltage in the form of heat, both through the regulator and back into the stator. That can (and often does) eventually burn components out. And there's really no cheap good replacement components for PMAs, only expensive good ones.

No, your stock 650 charging system is a 3 phase alternator very similar to the ones used on cars. Because of that, we're able to use cheap, but good, automotive regulators. The '80 and later charging system requires a ground switching/regulating or type A regulator. Here's a very inexpensive one from a Fiat .....

https://www.ebay.com/itm/VR794-1979...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

MMLxUAa.jpg


You will need a separate rectifier. Many of us have had good luck with this $10 unit .....

https://www.windynation.com/Rectifier/35-Amp-3-Phase-Bridge-Rectifier/-/218?p=YzE9MjA=

You will need to mount it on a heatsink and make a little harness for it, but it's pretty simple.

d0RyEPl.jpg


WFxgZEt.jpg
 
You don't need a "shunt" type regulator, that's a PMA thing and one of their weak points.
Yeah, you're right. Got my wires crossed there didn't I....:rolleyes:
Thanks for the links. I'll check em out.
Please don't drink the PMA kool-aid. It's very expensive and for the most part, tastes like shit
I'm guessin that you don't mind changing brushes either then...
 
Mailman had a lot of trouble using the very cheap 3phase rectifiers from Ebay (China). It wasn't until he bought through a reputable distributor (Windy Nation) that he had success. I paid similar for one from Vishay (International Rectifier) and it has been good for 1000 miles now.

Those units made by 5twins are very smart. If you want to replicate the combination stock rectifier/regulator then that Fiat regulator 5twins shows above is ideal because the body of it goes to ground so can be attached directly to the heat sink with the 3phase rectifier.

Correction: It was not Mailman but Danielblack who had the issues with rectifiers:
http://www.xs650.com/threads/stella-1977d-survivor-back-on-the-road.47329/page-23
 
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Maybe I'm just lucky, but I've never had to change my brushes yet. I have checked their length and will continue to routinely do so, they just aren't worn hardly at all yet. I do have N.O.S. originals in my parts stash for when the time comes. If you check eBay from time to time, you can usually score them quite reasonably, and I have no doubt they are better in quality than the repops.
 
Just keep in mind that your battery box is not a suitable ground because it's rubber mounted.
 
Cheap Chinese junk I'd guess. I'd stay away from both of them.
 
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