So you got it running now?

OK
But it is cranking over ?

I don't see that changing to a different plug should matter assuming there is nothing wrong with any of the plugs

Do you have 12 volts at the + side of the coil with the ignition on ?

If no you have a problem somewhere between the battery and the coil. Try running a fused wire directly to the coil bypassing everything If it then fires you need to sort out your switches and wiring.

If yes there is 12volts at the coil and it does not fire you have a problem between the ECU and the coil.
Check all the wires and connectors between them

If all this is OK you may have fried the ECU


FYI I have the iridiums in both bikes at the moment. I remember having to open them up as bit and straightening the electrode to get rid of a slight miss

guys you freak me out. Stop poking in the dark, do it with a system. This topic is going on for two months. Finding the problem shouldn´t cost more than a weekend. The Pantah is not a complicated engine. Finding a problem on a 907ie can be for sure more complicated.

Warwick, stop changing things. You´re making it more complicated to find the problem, you may even create new ones and please don`t constantly edit your posts, just post again. I always have to read your old posts again to see that there were things changed or added.

As for every gasoline engine that won´t start there are three very basic main possible issues: no cranking, no fuel or no spark.
We learned it does crank.
If you disconnect the fuel line to the carb and turn the ignition on you`ll see if the fuel pump squirts fuel through the line. If it does and not only a few drops things are fine. The carb could still be an issue but if after some cranking the spark plugs are wet that´s fine, too. If the bike stood for months or years old fuel can be an issue (not in your case).
Spark. If there´s none trace backwards. Check the spark plugs, the plug wires (an analog multimeter should basically show a short), measure the coils. Unless you modify things here there`s no need to check polarity or if the coils/cylinders were connected reversed.
If as higgy states at least 10V arrive at your coils they should fire. Your battery should be fully charged of course.
If all that shows no result measure the output of the pick-ups. (check pick-up/flywheel clearance and pick up bracket marks - if nothing was done to these parts this is not necessary)
If this is also all fine I`d have the Marelli Digiplex tested somewhere.

Of course there can be more which brings me back to my last unanswered question. What were the things you did on (or should I say to) the bike after the last time the engine still worked ?
Assuming all the above is ok this`ll only leave incorrect ignition timing which could come from attempts to adjust it, incorrect belt change or replacing the belt pulleys. Did you do any of this ?
(A clogged fuel return line will only show effect after some riding, not when starting a cold engine. Stuck valves on both cylinders are imho unrealistic).

The spark plugs are not your issue. They will either fire or not. If they work well with the ignition system is another story, but for the engine starting or not starting that`s irrelevant (Iridium NGKs didn´t work at all on my 750, the 906 or 907ie may handle them better).
Btw. the RA6HC are for the 750 you`ll need the RA8HC.

There`s no need to fiddle with your wiring now unless you changed it after your last ride or if it was damaged by your little fire mishap. If you want to know if your alternator works measure the voltage over your battery with engine off and then start it. Voltage should go up for 2 volts or so. If there`s no change it`s no good sign.
Please don´t get me wrong. Of course broken wires need to be fixed, filters cleaned or replaced etc but that´s not direct part of tracing the issue.

I hope I didn´t piss off anyone. I just feel a bit grumpy these last days, sorry.

G.

G, I think I'm a bad influence

regarding the red wire, my guess is you have an aftermarket regulator/rectifier as not all need it. See ie the description of the Electrex regulator.
https://app.box.com/s/r16ixjegwfl7aq3ybd0c

Just a comment in passing
I often go back and re-read a post from the beginning. Its a habit I developed from reading hundreds of pages of technical documentation. It does not always sink in the first time and as we all know language even your native language can often be ambiguous. I find myself often wondering how a point I totally missed the first time becomes so blazingly obvious at some later date. Also I often find it comes at a price I could not afford to pay

Glad to hear Romus got it going

Let us know if you go to the Champions and if they made a difference in the way your 906 runs.
One more opinion could never hurt

G, we are lucky in the US to have McMasterCarr. 99 times out of a hundred they will have it to your door the next day. Especially little odd ball parts like woodruff keys