Cleaning off the mothballs...

crashcourse

XS650 Addict
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Hey All,

Long time, no ride. Almost exactly three years ago I limped home on my XS650. I had only a 6 mile commute, and it died several times on my way home, any time I let the rpms drop. Every time I thought it might not start back up, but the old girl did not leave me stranded and I made it home. My son was born a month later, so I never had time to even troubleshoot. Two kids later, I'm finally in the mood to wrench again.

I started by checking the things that were wrong last time I had trouble like that; checked the ignition coil, resistance was right at nominal. Checked the alternator brushes, one is right at the line to replace, the other only slightly longer. Since I never checked the battery or charging voltage, it very well could have been the problem, but maybe not. I still suspect the coil, but I'll wait until I can try running the engine a while and get the coil warmed up.

For good measure, I pulled the carbs and checked for varnish and junk. So far it looks good. I need to get a battery and new brushes and see if I can start it and re-create the original problem.

Once I solve the problem of the engine dying at inconvenient times, I need to do some serious cosmetic work. Replacing worn, cracked parts, painting the tank and sidecovers, and just making this bike shine again, are all on my to-do list. I've got an engine oil leak that needs to be addressed, and maybe some reliability upgrades. So I hope to use this thread as a log of my efforts, humble though they be.

Progress will be slow, because most of my time to work on it will be when the kids are either playing outside or are in bed, but I'm not in a hurry. its just nice to be working on the bike again.
 
Your symptoms sound like your battery got low or died. It could be that the battery failed or just that the charging rate wasn't sufficient to keep it charged. The worn brushes you found might be the issue. When they get too short, it messes with the charging output. It can be too low, intermittent, or quit all together. I'd replace the brushes first thing then do the simple charging system check. Measure the voltage output at the battery terminals at idle and revved. You should see around 12 at idle and that should climb into the low 14's when you rev it to about 3 grand.
 
I'll put up pics when I have a chance to work with decent light. I'm going to get up early and replace the junction box in the ceiling and install an outlet so I can hang a real shop light., which should help a lot.

Also, sometimes I am really impressed with my past self. I was getting ready to put in an order at MikesXs for brushes and jets (5000 foot altitude difference), and I thought, "I must have kept the jets I was running in Utah, but where are they?" So I went looking and found not just the jets, but also a brand new set of brushes from the last time I ordered something from Mikes. To top it off, I also found my log book where I wrote down things like what jets I had in it (my box of jets has multiple sizes), so I both have the hardware and know which hardware to use.

I am still going to order replacement pilot jets (these are pretty worn from multiple cleanings), but the brushes were a nice find, and I'm sure the log book will be invaluable.
 
Welcome back, XS's don't like to idle below about 1300rpm it can cause them to die at a stop. If your bike is anything like mine the tension spring on the idle adjustment screw is 40+ years old and the idle screw will creep out over time (and vibration?) and the idle will slowly imperceptibly drop until its to low and the bike will die at stop signs and lights unless you bump the idle back up. I have to adjust mine pretty frequently.
 
I limped home on my XS650. I had only a 6 mile commute, and it died several times on my way home, any time I let the rpms drop. Every time I thought it might not start back up, but the old girl did not leave me stranded and I made it home.
Was there any loss of power when this happened? Reason I ask is it could be as simple as a fouled plug/ignition issue on just one cylinder. Limping home on one cylinder, you have to keep the revs up or it'll die on you.
 
Was there any loss of power when this happened? Reason I ask is it could be as simple as a fouled plug/ignition issue on just one cylinder. Limping home on one cylinder, you have to keep the revs up or it'll die on you.
I didn't know you could limp home on one cylinder
I thought un burned gas in the bad cylinder would get into the oil?
Learn something every day
 
Nope... I've done the one cylinder limp on Honda's, Norton's, XS's.... you name it.... 'bout every twin I've ever owned at one time or another.
Wow (note to self) Put that one in the bank Good to know
Thanks Jim
5 miles 10 miles ?
 
Most were that short...yeah. I do recall one out in the Idaho back country... 78 XS about 40-50 mi to home on 1 cyl. Ya gotta love these bikes.
I take it the un burned just goes out the exhaust
Good to know
 
I didn't know you could limp home on one cylinder
I thought un burned gas in the bad cylinder would get into the oil?
Learn something every day
Hi Grey,
nah, the unburnt gases will just whiffle out into the atmosphere.
If your bike has a siamesed exhaust the unburnt gases will mix with the working cylinder's hot exhaust gases.
The gas mix will still just whiffle out into the atmosphere but with the occasional KA-BOOM!
 
That KA-BOOM can be pretty damn severe. If you want to try a KA-BOOM then flick off the kill switch and run the starter a little to pump up the exhausts with petrol vapor. Then switch the ignition on and start the bike :smoke:. I did it by accident recently.
 
Got a light hung up (after installing two new receptacles, replacing the one that was wired backward and not rated for aluminum wire), checked the carbs (pretty darn clean actually), installed the brushes, and got the carbs back on. I need to finish re-assembly check the plugs, and hopefully get it started this week. If I can get it to start off the car battery and the charging voltage checks out I'll buy an actual battery and run it around for a while and see if any problems appear.
IMG_0326.JPG IMG_0327.JPG
 
Got a light hung up (after installing two new receptacles, replacing the one that was wired backward and not rated for aluminum wire), checked the carbs (pretty darn clean actually), installed the brushes, and got the carbs back on. I need to finish re-assembly check the plugs, and hopefully get it started this week. If I can get it to start off the car battery and the charging voltage checks out I'll buy an actual battery and run it around for a while and see if any problems appear.
View attachment 178626 View attachment 178627
Be careful using a car battery, the amperage on some of them can be a little to much for a motorcycles electrical system.
 
Got up early and put it back together, then hooked up to my car battery and started her up and ran for about 15 minutes. Charging voltage was 13.2 at 3k rpm. Video here.

Next steps: Tear it back down to fix my oil leak. Make a list of parts I need to replace. Rebuild it. Ride.
 

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Be careful using a car battery, the amperage on some of them can be a little to much for a motorcycles electrical system.
Hi Rustie,
time for you to take an electrician's evening class. It's the 12 Volt battery's Cold Cranking Amperage that matters.
My XS650 sidecar rig has a full size car battery instead of the stock one.
600CCA instead of the stock battery's14CCA spins the starter and works the ignition for a half-turn start on cold mornings
 
At only 13.2 volts, your charging output is rather low and warrants further investigation. If the slip rings are really dirty, that can affect the output. You might try cleaning them if you didn't already do so when you replaced the brushes.
 
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