1981 XS650 Special - Build Thread

Yeah, keep that in mind if you need any niggly bits....thinking I've an '81 untitled frame in the pole barn along with some parts and pieces that went with it, mostly junk but perfect for low budget maintaining.
I know Union and Independence well enough to find my way out and back home again.
Might have to have coffee in Rabbit Hash someday, pet the mayor, toss him some treats......
 
Yeah, keep that in mind if you need any niggly bits....thinking I've an '81 untitled frame in the pole barn along with some parts and pieces that went with it, mostly junk but perfect for low budget maintaining.
I know Union and Independence well enough to find my way out and back home again.
Might have to have coffee in Rabbit Hash someday, pet the mayor, toss him some treats......
I’m very close to rabbit hash! Coffee sounds good! I know they mayor well!
 
Yeah, keep that in mind if you need any niggly bits....thinking I've an '81 untitled frame in the pole barn along with some parts and pieces that went with it, mostly junk but perfect for low budget maintaining.
I know Union and Independence well enough to find my way out and back home again.
Might have to have coffee in Rabbit Hash someday, pet the mayor, toss him some treats......
That frame in your pole barn doesn’t happen to have OE exhaust does it??
 
Another thing you can do to "fine tune" the idle circuit on the BS34s is change the air jet. This doesn't have as big an effect on the idle circuit as changing the pilot jet would, so you can make it just a little richer by reducing the air jet a size or two. Also, even an all stock BS34 equipped 650 likes one size larger main. It's just happier that way, lol.
 
Day 33

Finally got my license plate for the bike. The PO had never been through the process to have the title switched over into his name and the bike was an out of state transfer, so the entire process took longer than planned but we got it done. I'm legal now!

Today I wanted to tackle the brakes. I was able to source some NOS OEM kits for the Caliper and the Master Cylinder, but I didn't have any luck finding affordable OEM brake lines. I definitely wanted to change the lines because the date code on the lines
were dated 6/80. I ended up buying a set of aftermarkets from MikeXS even though I really wanted factory lines. The aftermarket lines did work fairly well, and I figure if I get a few years use out of them, that for the price it was a win.

The front brake did work some but felt spongy and definitely wasn't working at full potential. In a dire situation it would have been dangerous. Both the Master Cylinder and Caliper were nasty. Hydraulic brake systems are one of those things that fall into the category of "out of sight, out of mind" where as long as the brakes are still working that I tend to not think about em.. It's always surprising to me when I open up a system that needs attention, just how nasty they can become. This one was on exception for sure.

There was a little pitting on the Caliper Piston but was better than I thought it would be considering that poor state when I first open it up. I was able to clean it up and felt comfortable with it. The Master Cylinder had no damage and cleaned up nicely. I put in the new parts and put everything back on the bike. I installed the new lines and bled them without without issue. Now I have a good firm brake. I hate it this time of year when you can't jump on it and take it for a test spin.

The Chrome on my Horn was pretty rusty and I had found a used one that was dirty but based on the picture looked like it was rust free so I took a chance on it. Cleaned it up and the Horn turned out really nice. It's amazing how just changing a few simple things can really start making a difference. I'm really glad I decided to keep this bike original, and I'm already looking forward to the next step, whatever that is, don't know yet but I know I'll have fun doing it!

There's just something about projects like these that bring me the most joy. I don't know about the rest of you, but I often will go through a project like this where I have tons of fun while I'm doing it, only to get to that day when I clean up my tools, put em away, and realize I'm done. I sorta get a feeling of sadness that it's done. That lasts for like 47 seconds then I'm already on the hunt for another project. I may need an intervention.
 

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I have tons of fun while I'm doing it, only to get to that day when I clean up my tools, put em away, and realize I'm done. I sorta get a feeling of sadness that it's done. That lasts for like 47 seconds then I'm already on the hunt for another project. I may need an intervention.
Just get out and ride it. You will find things that aren't just right, and it will break as well. These machines are anvil reliable to a point, but they still require a regular dose of attention.
 
Yes, being an older bike, it does require more maintenance, and at more frequent intervals, than a newer bike would. And as you read around the site here, you'll find many little inexpensive mods you can do to make the bike better. So, even once it's up and running, there's still lots you can do to it, lol.
 
Day 40
I've developed a problem that I need some help on. My charging voltage when the bike is running is high. At 3k RPM's it darn near hits 18 volts. I didn't run it long like this. I seen it peak and shut it down. This is a new problem and previously it would put out about 14.5 volts at 3k RPM's. This bike is an 81 and has the solid state Reg/Rectifer. Does this sound like a Reg/Rectifier problem? How do I test my Reg/Rectifier?

On a positive note (no pun intended) I did get me a new sump filter and put that in. Cleaned the oil filter and put some fresh oil in it. Also found a pretty nice used front motor mount. Mine was just nasty, and it was all I could focus on every time I looked at the front of the bike.
 

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Your '81 uses what's called an 'A' type regulator. Power is sent to the rotor full time and its ground is regulated by the regulator.
Unfortunately, unless you have an electronics bench set up to test regulators, there's not much you can do short of replacing it and seeing if it fixes you problem. Yours going high definitely sounds like a regulator.

Have a read here... https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/
 
CSF rule Cheapest Simplest First .
Not read through but I would service the charging regulator circuit . If it short-circuits to ground on the downside before the regulator Perhaps regulator functionality will not be there
Connector / Connectors is the first service point . Then inspection of the wiring . Perhaps measure Resistance to ground
On a side note it can happen that the regulator blows so it overcharges and fries the rotor also.Suzuki had those
in early eighties but was regarded as a defect design. Causing expensive repairs difficult to find. Not heard of it on other bikes
The design is better if the regulator circuit goes open and stops charging saving the alternator.
 
All you can easily test on the combined reg/rec is the rectifier portion. If that proves good then you could still use that part of the unit (disconnect the regulator wires) and get an automotive regulator. But, as you'll see in that thread Jim linked to, replacing the rectifier is easy and cheap too.
 
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