brainstorm ignition problem

[RUSH]

HI EVERYBODY!!

Im getting ready to diagnos a new problem with the bike, '78 XS11, that just started happening. Here are the symptoms. I turn on the key and hit the starter and it will spark at first, but if I let off the starter I get no more spark on the following cranks. Ive pulled the seat and messed with the loom connectors and that worked to get the bike to fire again. The next time this happened I kept cranking and flipped the key off then on and the bike fired back up. My past experience says to pull the loom connectors apart and clean them up, but I'm wondering if there might be something else going on. Any ideas?

[Getty]

If you were able to make things better by wiggling the wires/connectors, I would say that is a great place to start. Dielectric grease, a rag and about 1 hour should do the trick. Be careful when disconnecting things. Look closely at those connectors. Look for bad cracks, wire frays, loose connections, and brittle connectors. Clean and lube it all up.

Look into the tech tips / search. There are specific resistant values for the caps, wires, and between coils.

[DiverRay]

The ballast resistor is bad. It lives on the left frame rail, just below the coils. should be an easy fix, as I think you can still get them. If not, let me know....

[AlanB]

Hi Rush,

Ray is spot on; Current goes to the coil through the resistor during "normal" running, but bypasses it when cranking. Problem is in (or around!) the resistor.

It can safely be bypassed for diagnosis, but some run without 'em anyway!

AlanB

[datter]

Originally posted by DiverRay
The ballast resistor is bad. It lives on the left frame rail, just below the coils. should be an easy fix, as I think you can still get them. If not, let me know....

I thought the coils were under the left hand side cover on the engine?

[AlanB]

Hi Datter,

The pick-up coils, which send the signal to fire the ignition, live under the left-hand engine cover.

The HT coils, which produce the spark for the plugs, are up under the front of the tank. You can trace the plug wires back to 'em........

Similar name, different function.

AlanB

[datter]

ok thanks for the clarification. I think I have a problem with one or the other, but I won't hijack the thread.

[egsols]

The ballist resistor can be bypassed easily. The leads should be male and female so once unhooked from the resistor they can be connected to each other. This is what had been done on my bike by the PO.

Below is a pic, borrowed from TC showing the resistor just below the tank isolator.

http://www.xs11.com/forum/images/tip...5done_left.jpg

[TopCatGr58]

However,

A word of warning!! The TCI wants to see a total of 3 ohms resistance on that coil power circuit that it provides! When you bypass the resistor with OEM coils, you have reduced the ohmage by 1/2 which draws more power THRU the TCI, and can burn it up! Also, the OEM coils were designed to run on ~9 volts, which is what it gets when the power is run thru the resistors, but would get the full 12 volts IF the resistor is bypassed, and this TOO can burn up the OEM coils!

When you put on aftermarket coils that are rated at 3 ohms and 12 volts, then you can safely bypass the resistor without harm to either coils or the TCI!
T.C.

[egsols]

Yes, it may not be safe to run without the resistor using stock coils, but bypassing it will let you know if it is cooked and if it needs replacing.