R90/6 - no spark

[Red1974]

Ok my bike has no spark......new plugs and wires, new coils, new Odessy gel battery, valves adjusted, carbs rebuilt, disconnected battery before working on points.......no spark......as electric is magic to me can someone talk me through this? The bike ran before I did replaced these parts. What the heck? Thanks Red1974

[20774]

Did you reinstall the small jumper wire between the two coils? Without that wire, you'll get no spark AFAIK.

What work did you do on the points? Are the points closing and opening like they should?

Hmmmm...maybe your carbs are creating the no spark situation...:nyah That's a joke son... :wave

[wecm31]

Just throwing out some of the obvious, you never know....

Plug wires fully seated in coil? Plugs fully mated to the lead cap? Plugs are touching engine to provide ground for the spark?

Could be the points as well, but my ride is electronic so I can't offer much.

[Red1974]

jumper wire is there, points are opening as they should.......no spark

[rpeckham136133]

Do you have a means to check voltage, either a probe or a voltmeter?

The first place to check voltage would be at the coil: one side should show a steady 12v, the other is being broken by the points, as they open and close.

The steady 12v is supplied by turning on the key, so if you have nothing there, you will have to find where the problem lies. If the "break" is not there, you will have to get into the points.

Good luck ! :thumb

[20774]

What's the resistance from one spark plug cap all the way over to the other spark plug cap? You should see something like 20K ohms total resistance. I can imagine that if the resistance were quite high, you might not get spark.

What kind of plugs are you using...just curious?

[88bmwJeff]

One suggestion would be to start replacing the new parts with the old one piece at a time to see what the problem may be. Did you replace the condensers (I think that's what their called) with points? Although I don't have bike with points, I've read a lot about new condensers being bad.

[Red1974]

the plugs are Bosch Super R0 782s......I bought them from one our reliable parts purveyors, I did not replace the condensor with the points. I do have condensor on the way from Capital cycle. Is it possible that my Diode board is kaput? I do have a digital voltmeter. Looks like I'm going to learn how to chase electrical demons with it. Thanks for the help folks Red1974

[20774]

I've never heard of those plugs; can't find that number on the web, although I didn't look too hard...yttrium? Personally, I think you'd be better of with the standard Bosch non-resistor plugs or the equivalent in NGK.

The diode board shouldn't have anything to do with sparking. The diode board is part of the charging system, not the ignition system.

You said no spark...what did you see to indicate that? One of the best ways is to pull the plug, put it back in the spark plug lead, and lay the threads of the plug against the engine fins. Then crank the bike. I'm assuming that the bike is cranking and just not starting...is that what you mean by no spark?

[PSanborn]

Did you replace the front engine cover? If you did, I'll bet you pinched the wire leading from your points. The wire must lay in just the right position or it will be pinched by the front cover.

With everything you replaced, the odds that something is defective is slim.

My money is on a pinched wire.....if it got pinched, it's broken.

New points..properly adjusted...and she'll spark right up.
I speak from experience.......

Pete

[Red1974]

thanks I'll check the points wire...makes sense......Yup,I grounded the plugs to the cylinder head no spark........plugs are WET

[DennisDarrow]

Are you getting voltage across your points? Is there a tiny spark there when they close?

[James.A]

Did you replace the front engine cover? If you did, I'll bet you pinched the wire leading from your points. The wire must lay in just the right position or it will be pinched by the front cover.

With everything you replaced, the odds that something is defective is slim.

My money is on a pinched wire.....if it got pinched, it's broken.

New points..properly adjusted...and she'll spark right up.
I speak from experience.......

Pete
I've experienced this as well. It's the kind of thing you never think of once you get the hang of putting the front cover on without creating trouble. Good thinking there, Pete. New perspectives always help.

[Bombayduck]

OK, go back to before you did all the work. Was the bike able to start then? If yes then you must have installed something incorrectly or have a loose wire or a broken wire somewhere. Go through what you did (except the carbs) step by step and check everything that you worked on very carefully. Put the old plugs back on first just to see if it's the plugs.:banghead

[Red1974]

Ok thanks everyone......I'll trace my steps and check for a pinched wire,it has to be something simple......I'll let you all know how things turn out. Thanks Red1074

[scjack]

You said that you installed new wires.....I am assuming that you meant new spark plug wires. Did you buy the correct type for your bike? Some models require resistor caps and some don't. I think that yours doesn't but I can't remember since I haven't owned a /6 for a very long time. Check and see.

[cjack]

All the airheads use resistor plug caps. They were 5K back before the new version airhead...might have been afterwards also. The wires were solid copper core, and the caps resistor type. The points ign works well without resistor caps, but causes rf interference.

[cjack]

Ok thanks everyone......I'll trace my steps and check for a pinched wire,it has to be something simple......I'll let you all know how things turn out. Thanks Red1074

The points are probably not closing all the way. There was a bad run of points made with a too high rubbing block. Check your old points block and compare. Get the points that say made in Germany.

[beemerPhil]

A friend of mine once put a new set of points in his Fiat X1-9, and called me afterwards, when it wouldn't start.:violin

I found the little piece of rust-proof paper was still between the points.......:stick

So......How did he set the gap?:dunno

[Dave Backmarker]

One other thing to check. Did you rewire the coils correctly? There's a blue wire with a green stripe that's attached to the primary (not the ignition wire) side of one of the coils. On the same coil, the other primary has the jumper running from one coil to the other. On the second coil, on the other side from the jumper there's primary black wire that runs to the condenser. To visualize this, the wires run in series from the starter relay to the coil (providing power to the first coil), then on to the second coil and the circuit is connected to the condenser which is of course a capacitor that must be in place between the primary voltage and a switch (points).

You can disconnect primary coil wires from the starter relay and the coil and then between the coil and the condenser and check for continuity. Use your volt-ohm meter, set it an ohm (should have an Omega symbol) and touch the two probes to each other and look at the reading. It probably reads zero which for practical purposes is what you'd hope for in a short wire (yes, of course any wire will have a finite resistance but you're looking for binary situation; a broken wire or a whole wire).

AND, ALWAYS disconnect the battery BEFORE you remove the front engine cover as you can short out the diode board if the battery is connected and you bump the front cover against the diode board.

[Weasel]

How old are the points? I finally had to replace mine with the spare set I kept under the seat. But the first ones lasted 33 years! Indication was that the bike wouldn't start, and I had a hunch it was the points. Popped the new points in and she ran fine!

[37071]

"My money is on a pinched wire.....if it got pinched, it's broken"

Try starting with the front engine cover off. If engine starts right up.... DAMHIK

[PGlaves]

This system is too simple to be very hard to diagnose.

1. Take a 12v test light probe. Clip the wire to ground. Prop the points open with a match book or business card. Key on. Touch pointed end of tester to the movable points arm. Does the light light? If so good. If not, trace the wire back to coil 1, then coil 2, then onward. Where is the power lost. Disconnect the condenser and repeat the test. It could be shorting to ground in the condenser.

2. If the light lit, then allow the points to close. Light go out? If so, good. If not, check that the points are actually making contact. If not, readjust.

3. If the light was on with open points and off with the points closed and you don't get spark then check the secondary circuit of the coils, the coil wires, caps, and plugs.

It has to be there somewhere.