Sudden loss of engine power

[LoHo]

I was tooling home from work last night and while coming up to speed off of a stop light the bike just stopped running. No cluck or puff of smoke, just stopped. I coasted in, trying to get her going with a bump, but no dice. The starter turns the engine, and it seems to try to run with throttle, and a quick look leads me to think it isn't fuel, as all lines are good, prime didn't help, and it didn't wind down, it just stopped. I pushed her home, but haven't delved in yet.

The sudden nature of the loss points me toward something electrical, but something big enough to shut her down, rather than run rough (like one coil down). The starter turning tells me that electrical power is still available. The almost-running at throttle tells me the cam chain is still in place, and I didn't hear anything to point to jumped teeth.

I know I should look her over before asking, but I'm sitting here with the kids at summer school and love to take advantage of the knowledge base we have here.

If my old horse keeps having issues I may make guru yet.

[dbeardslee]

Did you check your fuses?

[DGXSER]

Off the top of my head, electrical that keeps her running consist of fuses as DB mentioned, Pick up coils which usually only fail one side at a time, TCI, coils which isially only fail one at a time, and plugs. Hmmmm....also voltage reg/rect, alternator, and battery. If she bumps over, but no spark which it sounds like, I'd start at the battery and check voltage. Then check plugs for spark, and work backwards toward TCI. Maybe work the reg/rect path after the battery?

But I would agree if it just plain went from full gittyup to none without stumbling a bit, it should be related to the magic smoke!

[John]

If your bike is older than an 80, try bypassing the ballst resistor. The symptoms you described sound like that may be the culprit, if it will run only while cranking it.

[prometheus578]

I know I should look her over before asking,

yeah, no kidding. Give us something to work with, will ya?
At least stick a screwdriver in a plug cap, crank it and see if'in you have a spark jumping from the cap to the head. That would rule out electrical. Oh, spark timing could be an issue, but that's very rare... very rare.

Good... keep the tank on prime and open one of the float bowl drain screws. (actually, just to be thorough, open #1 and #4's bowls) If ya got's a good amount of fuel pouring out, that rules out the fuel issue. Sure... ya could have a bad carb, but all four at the same time on a bike that was running well a moment ago? No.

As the others have covered the electrical stuff fer ya, I'll go for something else.

The almost-running at throttle tells me the cam chain is still in place, and I didn't hear anything to point to jumped teeth.

Wrong. You won't hear anything at all when it goes. Engine is too loud. Wanting to run at wide throttle is a partial clue. Now... you may be lucky... may have just jumped one tooth/link and may have not damaged anything at all. Bike won't run... but'll sure sound like it wants to start.

Now... then again... might have jumped several teeth and sent a piston or two upward into a still open valve. Yeah, it'll still sound like it wants to start, too.

Bike will still run with one bent valve... if it was a stuck valve and not a chain issue. Hell, I rode most of the rest of the way to Denver once on three cylinders. Sounds like you may have had multiple piston/valve strikes.

BUT... until you run some simple tests... we'll never know.
Check the fuel at the bowl....
Check for spark at the plugs...
Not 100% reliable, but... pull all the plugs, and one at a time, crank the engine over whilst having a finger jammed in the plug hole. You should hear a farting noise like a night after bad Mexican food... and the pressure should push your finger out of the hole.

Now, if the farting noise sounds real weak... like from someone who's spent a few years in Cook County Jail... and there's no pressure pushing a'gin your finger, you have larger issues.

Test and reply.



EDIT: Good point, John... But the bike would start and run while cranking... but would die as soon as he took his finger of'fa the starter button. He stated only that the bike "seems to TRY to run..."
Then again... maybe that's not what he meant to say. He's not good at testing and explaining things, is he?
HAHahahhahaa

Check a coupla things out, LoHo and come back with the results.

[prometheus578]

Well, DUH!
What was I thinking... or not thinking.
Those tests I mentioned can be used if you don't have a compression tester.
If you have a compression tester... use it.
And as an old timer here LoHo, I know I don't need to remind you that you'd like to see around 142psi at each cylinder.

[LoHo]

First check over:
Fuses okay.
No spark when cranking, then a spark when I turn the key off.

[prometheus578]

What... you couldn't have done that earlier and saved me from all that writing?

Ok... front to rear, top to bottom...

It's not at the ignition switch, as you've got power.
It's not the coils, as you get a spark(which is normal when turning the key on and off) and we know that we're getting power to the coils because of it.

The TCI interupts the power going to the coils... based upon "timing" input from the pick-up coils.

Now.. these bikes will run on three cylinders, but not really on two. Now, if one of the pick-up coil's wires might be broken... you'd get spark on two cylinders. You get no spark on any cylinders. Though it's possible, but improbable, that both pick-up coil wires broke at the same time, you should check down there for damage. It's more likely that the connector in the wire from the pick-up coils to the TCI became unplugged.

If everything looks good there, we may have to look at a failed TCI.

[MindWebs]

fuses ok???

it's not the fuse itself that goes bad on these bikes.

it's the fuse holding tabs(fuse block).

jump a wire from one side of the ignition fuse to the other and see if it will
start and run with that in place.

then test all others in same way.

if this make the bike run, the fuse block is bad and needs to be replaced.

if you are still running original fuse block, You NEED to replace it or it will leave you stranded.

see here for directions:http://www.xs11.com/forum/showthread.php?t=14052
P.S. they are not that expensive 20bucks(block and connecters) and it's done.

good luck.
Webs

[TopCatGr58]

First check over:
Fuses okay.
No spark when cranking, then a spark when I turn the key off.

Prom, I'm surprised...you've been away too long.

No spark when cranking because his battery is weak, and probably putting out a bit less than the 10.5 to control the TCI, but once he stops cranking, then the power surges to the coils for an instant, the drops allowing the field to collapse, and poof, a little spark!

I say, check his battery voltage...then jump it with a car battery...car NOT RUNNING, and if starts and runs, then check voltage at 2500 rpm. If not near 14.5 volts...or close to only 12 or so, then Reg/Rect or ALT problems not charging battery, dead/dying battery!?

T.C.

[madmax-im]

This may sound silly but you didnt by chance hit the kill switch accidently?

[DGXSER]

Good thought BNE, but, the kill switch thrown would kill the starter circuit.

[Geezer]

It could be a bad kill switch. It wouldn't be the first time I've seen those contacts fried. Checking and cleaning the rest of the contacts in the ignition system wouldn't hurt either as would testing the ballast resister.

Geezer

[LoHo]

Final verdict:
Snapped solder joint in the pick-up coil wire. When my original wires gave up, it was in a couple of spots, one of them right next to the top entry point. My feeble soldering skills were overwhelmed by trying attach to a rough stub of wire right next to a plastic piece. This time it snapped off clean and killed my spark. When the original wires failed it was gradual and intermittant; the original wires basically crumbled to copper power, but did work off and on. When this one snapped, the bike just quit.

Thanks all, especially Prom, who has developed outstanding typing skills and a solution to every problem.

Isn't it interesting what range of problems can result in "won't start" and "running rough".