Starting Issues & Backfiring

[DiverRay]

Kill switch! From the other side of the planet, that's my choice. I do NOT remember the colors, but bypass the kill switch and see if it fires. The reason for the backfire after no start is the coils build up a "charge", and discharge when the electricity is taken away and fire. ( dumb down explanation )

[TopCatGr58]

Hey Dan,

It will take a little more work, will probably have to take the gastank off, but the emergency fall over shut off switch can also become flaky, and unplugging it will also allow bypassing.

Also, bypass the ballast resistor...jumper the harness wires....however, it should START if the BR is cracked, but would not continue to run because the TCI bypasses the BR during cranking/starting, but then routes thru it when actually running....so it really shouldn't stop it from actually at least starting/firing during cranking.

Stupid question...are you running the OEM fuseblock/glass fuses or solid ATCO style?

Take a voltmeter with you, and monitor the battery voltage while cranking, even though it's LOAD TESTED, it may still be dropping too low while cranking to power the ignition?? DO you have a spare 12 volt battery you could bring to jumper to the IGNITION fuse circuit separately? I had a battery that was strong enough to crank the engine, but was just a tad too weak otherwise, and wouldn't fire the TCI/COILS!

Then IF you get it started, check the charging voltage while running to make sure it's going up to ~14 at 2500 rpm....if it stays at 12 or less, then you will have found WHY it died!

GOOD LUCK, let us know what you find!

T.C.

[BowlingSS]

Hey Dan,

It will take a little more work, will probably have to take the gastank off, but the emergency fall over shut off switch can also become flaky, and unplugging it will also allow bypassing.

Also, bypass the ballast resistor...jumper the harness wires....however, it should START if the BR is cracked, but would not continue to run because the TCI bypasses the BR during cranking/starting, but then routes thru it when actually running....so it really shouldn't stop it from actually at least starting/firing during cranking.

Stupid question...are you running the OEM fuseblock/glass fuses or solid ATCO style?

Take a voltmeter with you, and monitor the battery voltage while cranking, even though it's LOAD TESTED, it may still be dropping too low while cranking to power the ignition?? DO you have a spare 12 volt battery you could bring to jumper to the IGNITION fuse circuit separately? I had a battery that was strong enough to crank the engine, but was just a tad too weak otherwise, and wouldn't fire the TCI/COILS!

Then IF you get it started, check the charging voltage while running to make sure it's going up to ~14 at 2500 rpm....if it stays at 12 or less, then you will have found WHY it died!

GOOD LUCK, let us know what you find!

T.C.

TC, there are no stupid questions.
"Stupid question...are you running the OEM fuseblock/glass fuses or solid ATCO style?"

Changing the fuse block is not hard to do. It will only cost about $10 if you need this mod.

Good luck.
Bill

[neJeff]

Kill switch! From the other side of the planet, that's my choice. I do NOT remember the colors, but bypass the kill switch and see if it fires. The reason for the backfire after no start is the coils build up a "charge", and discharge when the electricity is taken away and fire. ( dumb down explanation )

Found this old thread but I think you are describing the issue. I am resurrecting this old XS. It will crank and crank and crank and then shut key off it will backfire like a bomb. I did get it to actually start once today which is nice, most of the time just cranks. I'll try and bypass the kill switch.

[motoman]

Found this old thread but I think you are describing the issue. I am resurrecting this old XS. It will crank and crank and crank and then shut key off it will backfire like a bomb. I did get it to actually start once today which is nice, most of the time just cranks. I'll try and bypass the kill switch.

Do NOT bypass the STOP/RUN switch. First check that the plug-in connections under tank, right upper frame location has clean contacts. THEN remove stop/run switch from bars. Take apart being careful not to lose tiny internal spring. Drop ALL pieces including switch itself in a small cup of Evapor-Rust overnite. Remove pieces and rinse clean with water, put back together and install. Next, remove left side ignition cover and pull each of those ignition wires using two hands to try and separate wire. If insulation stretches, you found where wires are broken internally. Cut and repair. Both instances ARE a common issue with these ole' scoots.

[neJeff]

Do NOT bypass the STOP/RUN switch. First check that the plug-in connections under tank, right upper frame location has clean contacts. THEN remove stop/run switch from bars. Take apart being careful not to lose tiny internal spring. Drop ALL pieces including switch itself in a small cup of Evapor-Rust overnite. Remove pieces and rinse clean with water, put back together and install. Next, remove left side ignition cover and pull each of those ignition wires using two hands to try and separate wire. If insulation stretches, you found where wires are broken internally. Cut and repair. Both instances ARE a common issue with these ole' scoots.

Okay will do those things and hopefully get this baby up and running! Thanks for the input!

[neJeff]

So, on the good advise I went out under the cover and darkness and tried to start bike, nothing. Took the screws out of the cover and simply touched the wires a bit with my fingers, did not pull, just poked at them, very supple. For fun I started the bike and it fired right up! Now to figure out how to properly fix these wires, thanks for the help!

[motoman]

So, on the good advise I went out under the cover and darkness and tried to start bike, nothing. Took the screws out of the cover and simply touched the wires a bit with my fingers, did not pull, just poked at them, very supple. For fun I started the bike and it fired right up! Now to figure out how to properly fix these wires, thanks for the help!

easy......cut wire, slip a teeny piece of shrink tubing over either end. Shorten up a naked butt connector, slip wire pieces in and crimp. Slide piece of shrink tubing over repair and shrink it.....done. Do NOT solder wires as heat changes the molecular structure of teeny wires and it will break wire at same location again from flexing due to advance assembly movement......eventually, and when your 200 miles from nowhere.

[neJeff]

easy......cut wire, slip a teeny piece of shrink tubing over either end. Shorten up a naked butt connector, slip wire pieces in and crimp. Slide piece of shrink tubing over repair and shrink it.....done. Do NOT solder wires as heat changes the molecular structure of teeny wires and it will break wire at same location again from flexing due to advance assembly movement......eventually, and when your 200 miles from nowhere.

Okay great! Will get this going tomorrow! Thanks again!

[TopCatGr58]

Hey Jeff,

See Pick Up Coil Repairs: http://www.xs11.com/forum/showthread.php?t=543

A few more things to check, is your battery NEW or a few years old, and is it well charged?

Also, if the bike's been sitting for a good while/years, then you probably have a fair amount of corrosion in ALL of the harness electrical connectors, take apart, inspect for corrosion, spritz with electrical contact cleaner, reconnect. Next, check BOTH grounds, the main one at the battery (-) to frame, but also the 2nd ground strap at starter motor to frame under the carbs/airbox, again clean to bare metal. AFTER reconnecting then apply dielectric grease to the OUTSIDE of the wire/frame to insulate it from corrosion/rust...do NOT apply it to the frame metal/ground strap BEFORE securing/bolting down...it will PREVENT/create a restriction/resistance to the electricity trying to flow thru that connection.

Ensure battery is fully charged, and then use a voltmeter and test the voltage drop while cranking, if drops to ~10.5 or less volts, then the ignition system won't work properly, it'll still crank/turn the starter motor, but won't generate a spark.

Next, you've got a 79 F, should have the ballast resistor. It's harness connection can also corrode. IT is involved once the bike is running, but is bypassed during starting. Sounds like Motoman has you on the right track with the PU coil wires, but there are many other components to the ignition system, and therefore many failure points as well.

Good luck!

T.C.

[neJeff]

Hey Jeff,

See Pick Up Coil Repairs: http://www.xs11.com/forum/showthread.php?t=543

A few more things to check, is your battery NEW or a few years old, and is it well charged?

Also, if the bike's been sitting for a good while/years, then you probably have a fair amount of corrosion in ALL of the harness electrical connectors, take apart, inspect for corrosion, spritz with electrical contact cleaner, reconnect. Next, check BOTH grounds, the main one at the battery (-) to frame, but also the 2nd ground strap at starter motor to frame under the carbs/airbox, again clean to bare metal. AFTER reconnecting then apply dielectric grease to the OUTSIDE of the wire/frame to insulate it from corrosion/rust...do NOT apply it to the frame metal/ground strap BEFORE securing/bolting down...it will PREVENT/create a restriction/resistance to the electricity trying to flow thru that connection.

Ensure battery is fully charged, and then use a voltmeter and test the voltage drop while cranking, if drops to ~10.5 or less volts, then the ignition system won't work properly, it'll still crank/turn the starter motor, but won't generate a spark.

Next, you've got a 79 F, should have the ballast resistor. It's harness connection can also corrode. IT is involved once the bike is running, but is bypassed during starting. Sounds like Motoman has you on the right track with the PU coil wires, but there are many other components to the ignition system, and therefore many failure points as well.

Good luck!

T.C.

Thanks for all the good info, I am working my way through the wiring, etc. Also working on brakes.

Found the broken wire fairly easily, will work on that soon.

[skids]

I vaguely remember somthing about the magnetic field breaking down when the key is turned off, whick creates a spark in the high tension wires. Unburned fuel could inginte causing a "backfire"? Am I out there in oblivian, or could this be a symptom of what he is experiencing?

[motoman]

Not sure Sid........could just pick one.