Ignition wiring problen how to start yhe bike with no ignition barrel and keys

The most likely problem is a a short circuit in the ignition barrel. It would give all of the symptoms you are experiencing. Although the speedo may have an internal short as well. The ignition barrel is just a tube with switches in it, it controls the power distribution for your entire bike.

If the key comes with the replacement barrel and the existing switch was not damaged other than the barrel, yes it should start.

if u run a live straight from battery to live on starter moter should turn over telling ustarter motor ok , so problen in wiring hope this helps

Is the bike key yhe only key? or do you have bunches of keys on the ring? The connector sounds like it's messing with you.. I doubt it's the ignition itself. Check the wiring connectors coming from the ignition switch and the any wires running under your but, Just in case your bouncing got one that was run between the seat and something that would hurt it. (the wire) not your ****. Good Luck.

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I would not replace anthing yet! An intermittent light could mean that you simply have a wiring short! Get someone to help by watching your engine light, start your bike and do a wriggle test oun your wiring harness. You may find it to be no more than a simple wiring problem at the connector. You said there are no stored codes and the bike is running fine? No missing of sputtering? If not I would think the problen is no more than a possible temporary short in the wiring at the sensors

You definitely need to change all with a kit of : ECU, engine main switch, seat lock and you will get in the kit 3 new keys, 2 black and 1 red.The black ones need to be programmed from the red one at a dealer's workshop.Then store the red some place safe.

There's a procedure to recode new keys, so the immobilizer let's you use the new key, if (and only if) you have the master key (red). Look at this PDF:
http://www.wotmeworry.org.uk/manuals/Gilera%20Nexus/Gilera%20Nexus%20500%20Mk1%20Workshop%20Manual.pdf

Look for "Setting the Circuit" in the PDF.
Good luck!