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After replacing the spark plugs of my Rockster with NGK D8EA and a car's spark plug (because I couldn't get the original spark plugs), my Rockster began to fails to start. After many attempts, I tried to start with the spark plugs out of the engine and I realized that I haven't spark between the gap in neither of the spark plugs, even when I reinstall the original ones. Could anyone help me and tell me what could be the reason of my problem? I suspect of the hall effect switch, but I don't want to buy it and at the end the cause of my problem is another element, because you know that the hall effect switch isn't cheap.
Thanks in advance for your help and advices.

Did you ground the plugs to the engine when testing for a spark?

Yes, of course. Both spark plugs on each cylinder were well grounded. I even thought it was a problem of a block engine bad grounded, but it is well grounded.

I assume you have the 4 plug engine, that being said, your problem might be with the stick coils, these decay and fail with continuous exposure to engine heat.

Where can I find the "stick coils"? Is the individual coil that connect directly to the main spark plug or is the coil located beneath the gas tank that connects to the auxiliary spark plug ? Assuming I have a defective stick coil, why do the auxiliary spark plugs do not have spark either?
Thanks for your tips

Old on left and new replacement on right.



They fit to the primary plugs - center of each cylinder.

Any additional advise?

Why did you choose to replace the spark plugs?

Was the bike running poorly?

Was it starting OK prior to spark plug changes?

Are the main spark plugs (in center of valve cover) correctly connected? That means the electrical connectors at top of stick coils (which sometimes break), and the plugs themselves seated within stick coils.

I replaced the original spark plugs, because the bike was running poorly and they had two years installed on my Rockster. After replacing the plugs, the bike began to run more poorly (clugging) and after some starting attempts (in which the spark was intermitently failing), until finally no spark at all.

Pull all the spark plugs, install on the high tension wires and ground the body to the cylinder head, then turn the ignition on and see which plugs are firing and which aren't. An extra pair of hands might be helpfull, otherwise dfo one side at a time. Have all plugs out so there isn't the compression drag on the engine.

There are many things that can cause your problem, plugs, bad/failing stick coils, broken stick coil conectors, bad high tension wires, bad reluctors.....need to troubleshoot.

Hi again. I have tested the hall effect switch of my Rockster according to the method presented somewhere here at this forum and guess what: It worked perfectly!!!! I don't know what other can be the cause of not having spark in any of the 4 spark plugs. Any additional idea excepting the computer?

Hi again. I have tested the hall effect switch of my Rockster according to the method presented somewhere here at this forum and guess what: It worked perfectly!!!! I don't know what other can be the cause of not having spark in any of the 4 spark plugs. Any additional idea excepting the computer?

Excepting the engine controller, power to the coils (stick coils and secondary spark plugs combined coil) is sourced from battery through ignition key switch ("ON" position) for bikes with one Load Relief relay; the stick coils' power supply uses Load Relief relay 2 for bikes equipped with the second relay.

So a lack of spark at all plugs could result from:

Dead battery.
Wiring problem to & from ignition switch.
The ignition key switch.
Supply wires to coils.
Damaged coils.
Damaged electrical connectors for the above.

Finally, the lack of spark could certainly result from engine control computer problems, since the coils are triggered from the computer board.

A diagnostic check at the BMW Motorrad dealer would help confirm computer operation and any recorded system faults.

Just for the record.....
After many essays with the hall switch and everything that I've been advised here at the forum, guess what? My Rockster starts again. The problem? bad brushes compression spring at the electric starter. I've changed the spring, brushes and I've got spark at all the 4 spark plugs and obviously my little girl is running again.
Thanks to all that gave me hints. I'll be in touch.
P.S. Happy & Safe New Year 2011