New owner of a 1981 XS650 and I don’t know where to start

Melnic

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Very difficult to test a charging system w/o a good battery. That needs to be done first.
You can also disconnect one end of the battery. Put it on the charger overnight.
When you get up, disconnect charger from the battery (not just unplug the power)
Let sit an hour. Test battery voltage.
If its not 12.5 or higher (good battery should be about 12.7V sitting and charged) then its bad battery.
Know that a bad battery can STILL be 12.7V but be bad, a low voltage only tells you its bad, a proper voltage does not mean its good.
If bad, it would drop to about < 10V while starting.
Fully charged, it should be able to run the starter 5-10 times if not more EASY.
A bad charging alternator will kill a battery pretty fast. Every time a battery is discharged < 11.8V (sitting voltage)it will degrade the battery a lot.
 

JFAIR1

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Ill pull the battery and get a hold of a test light ASAP and report back. Marty, Ill catch back up to you after Thanksgiving. Thanks again.

Jim, I sent you a message about getting the original rotor rewound. Let me know if you got it.
 

Jim

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Jim, I sent you a message about getting the original rotor rewound. Let me know if you got it.
Nope, no message.

Want me to send you one, or should I let you figure out how to do it? :wink2:
 

JFAIR1

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Got your message, Jim. Thank you.

Got another question. My drive chain is rubbing on some kind of pin that sits under the sprocket. The pin has two bearing that look like they once were covered in a rubber. The rubber is gone and now the pin and bearings are exposed. Can you fellas point me in the right direction and what I need to replace. I’ll add pictures. Thanks again.
 

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Wingedwheel

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I’m not 100% sure but it almost looks like a tab has been added? Got a side shot?
 

5twins

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Yes, I think someone added their own chain roller or guide, not sure why. Obviously, it's not helping, lol, causing more problems than anything else.
 

JFAIR1

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I'll try and add a few more pictures. You guys think I can just take it off? I googled "chain roller" and found some generic parts. I might just replace it.
 

5twins

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It's not something you need. Like I said, I'm not sure why the P.O. put it on in the first place. Yes, I'd get rid of it.

Something else you'll want to do is count the teeth on your front sprocket. 17 is stock but some switch to an 18T to gear the bike up. This can cause issues because there's not much clearance available in that area. And it's not necessary because you can achieve pretty much the same results by changing the rear sprocket and leaving the front alone.
 

Wingedwheel

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Like 5T said, just remove it. While you’re in there, there is a guide that you should take a look at as well. It helps protect the shiftshaft and the charging system harness from the chain.IMG_2678.jpeg
 
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jetmechmarty

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Like 5T said, just remove it. While you’re in there, there is a guide that you should take a look at as well. It helps protect the shiftshaft and the charging system harness from the chain.View attachment 254531
I can’t be 100% at this point, but I believe that part was installed and the harness properly installed.
 

JFAIR1

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Update

Marty I tested the electrical system with a battery testing light. I got no light connecting the ground terminal to the battery ground. I pulled the battery and will be taking it to O’Reilly for testing tomorrow.

Wingedwheel I took the chain roller off and checked to see if that part you suggested was missing. It was in place. I’ll post pictures to confirm.

5twins once again you are right. The PO has replaced the 17t with a 18t sprocket. So how bad is it? Do I need to change it back? Can I get one aftermarket?

Thanks Guys
 

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jetmechmarty

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Based upon the bike’s modifications, it isn’t a highway cruiser. I recommend a 17 tooth front sprocket and 34 on the rear wheel. The issue is going to be what kind of wheel is that and what sprocket is available for it?
 

Kevin Werner

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It's not something you need. Like I said, I'm not sure why the P.O. put it on in the first place. Yes, I'd get rid of it.

Something else you'll want to do is count the teeth on your front sprocket. 17 is stock but some switch to an 18T to gear the bike up. This can cause issues because there's not much clearance available in that area. And it's not necessary because you can achieve pretty much the same results by changing the rear sprocket and leaving the front alone.
Forgive me for the late reply here with absolutely no animousity... I owned a XS650E as a young PFC or Corporal in the USMC with a rather tight budget. We worked from catalogs (JC Whitney and others in the day) and a countershaft sprocket "up one tooth" was 1/3 the cost of a rear sprocket down 2 teeth. I was humoured that my Blue Tracker arrived with that 18 tooth countershaft sprocket AND that the "Red Bike" had a 32 tooth wheel sprocket when I disassembled it. The 2 XS 650 s I have owned after my original purchase in the late 70's were both geared up. :)
 

5twins

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Yes, change that front sprocket back to the stock 17T size. If you change the rear, don't stray far from the stock 34T size. Yes, these bikes benefit from a gearing change, but just a small one. The key word here is "small". If you make a change, just go to a 33T or 32T, no less than that. Your rear sprocket looks like an original but you won't know for sure until you measure it's bolt circle .....

jtr850.jpg
 

Kevin Werner

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Yes, change that front sprocket back to the stock 17T size. If you change the rear, don't stray far from the stock 34T size. Yes, these bikes benefit from a gearing change, but just a small one. The key word here is "small". If you make a change, just go to a 33T or 32T, no less than that. Your rear sprocket looks like an original but you won't know for sure until you measure it's bolt circle .....

View attachment 254649
The stock gearing works very well with the available power and a step down on the wheel sprocket or a step up on the countershaft still works ok. There really is not enough power from the motor to go beyond that. But another issue is taking off in 1st and low speed maneuvering. Stretching the gearing out means raising the ALL of the ratios and soon you find 1st gear just too tall for low speed work without a lot of clutch work.
 

Wirenutt

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Yes, change that front sprocket back to the stock 17T size. If you change the rear, don't stray far from the stock 34T size. Yes, these bikes benefit from a gearing change, but just a small one. The key word here is "small". If you make a change, just go to a 33T or 32T, no less than that. Your rear sprocket looks like an original but you won't know for sure until you measure it's bolt circle .....

View attachment 254649
Totally agree, go with 17T front sprocket. I have a 32T on the rear, and that's as low as I'll go, as 1st is just low enough to get my 255lb fat ass moving on a mild uphill start on my SG.

I installed an "overdrive" 5th gear in my 76 when I had the transmission apart for repairs, and left the stock 17/34 sprockets on, and that seems to run very close RPMs in 5th as the 17/32 sprockets on my SG, without affecting the other 4 gears.
 

JFAIR1

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I checked the battery and it came back good for the second time in 6 months. So I‘m still at a loss as to what is causing me all the electrical problems. Guess it could be the wiring harness. Is there a way to check the stator and rectifier? I checked the battery two days ago and it was showing 12.73 volts. I left it off the battery charger and checked it 24 hours later and it was 12.71 volts.

Can I just leave the front sprocket at 18T for now? Will it tear anything up? At this point I’m just shooting for reliable. I’ll get this thing closer to stock after it quits leaving me stranded on the side of the road. I also found that the rear sprocket has 34 teeth. I did not take exact measurements of the sprocket
 
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