bike wont start gilera 125.help please :)

thanks well still waiting on the stator, do i just plug it in as normal when it arrives or is there anything else i should check??

 

You've checked anything that could be faulty that the CDI connects to, so when the new CDI arrives, disconnect the battery, swap them over, reconnect the battery and try it. The only other thing it could be is a faulty ignition coil, but let's try the CDI first as coils don't normally fail just like that.

 

ok thanks

 

,

 

i just found this Testing the CDI earth (CDI white wire)
Disconnect the CDI connect block again and making sure the flywheel block connector is reconnected check the resistance between the white cdi wire and a good earth (or battery -(negative) terminal)

You should have a reading of 0 Ohms as the white wire should be connected directly to earth.
if so you can move on to the next section... otherwise read on

If not disconnect the flywheel block connector and check the white wire again from there. If you now get a good reading but didn't before then there is a problem with the white wire between the flywheel block connector and the cdi block connector, it will almost certainly be the flywheel block connector which can sometimes become corroded or damaged. This must be rectified before proceeding.

Testing the Piaggio stator output (CDI green wire)
If the pickup reading is fine at the CDI connector block and the white wire is earthed ok then we can move on to the green wire. The ignition key must be in the 'ON' postion for these tests. The green wire carries AC voltage (approx 80volts) from the stator to the CDI which is generated by the stator as a power supply for the CDI. This is completely independent to the other stator coils (not shown on our diagram) which generate power to charge the battery and operate the lights and are not involved in the ignition circuit.

 

here it says the ignion key must be on ...?? http://www.pedparts.co.uk/blog/piaggio-parts-piaggio-ignition-fault-finding

 

You've checked all that you need to; that's the connections in the block connector that they say in the write-up could be faulty and they are OK. The coils in the stator are the right resistances so you should get the right voltages and signals from it. Check that the white gives 0 ohms and that confirms a good earth - any resistance indicates an iffy earth and you should clean all contacts that the white wire uses.

Set your meter on 200 volts AC and connect the red probe to the green wire on the CDI with the black probe earthed on the frame or a good earth point. Turn the ignition on and crank the bike over on the kickstarter or electric start and see if you see 80v AC or thereabouts on the multimeter when the engine is turning over. You might not see a full 80v as the starter doesn't turn the engine at full idle speed. If you do see 80v, then all wires and voltages are AOK and you can connect the new CDI unit.

 

ok thanks

 

Merlin got the cdi in the post and connected up to the bike today, but couldn't get it started, cos not getting any fuel to the carb

 

anyone awake

 

well just did same checks and bike still not working even after changing cdi

 

But are you getting a good spark from the new CDI? Test it by taking the plug out and earthing it against a good earth point and turning the engine over on the kickstart or starter motor. DON'T allow the earth contact from the plug to break as the high tension voltage not going to earth could wreck the new CDI unit!!

OK, a lot of Gilera machines have a small tank underneath the main fuel tank that feeds the fuel pump. This little tank can become airlocked and you need to force the air out of the system.

Stevep posted this in another thread and I think the same might apply to your bike.

Give that a shot.

 

took the spark plug cap off and put to the frame and kicked no spark and then put spark plug in and kicked and no spark still

 

@ SteveP

Can you help this guy with the electrical side of things from the ignition switch downwards? I'm not a Gilera expert and I need a fresh pair of eyes looking at this problem. No spark has to be either ignition wiring or immobiliser issue, unless you can think of something else that I've missed.

@ SPRunnerSP

Can you try this please? If you have a length of spare wire handy, let's test the ignition coil. Remove the spark plug and earth it as before, then disconnect the purple wire. Take a live feed from your battery live to the terminal that the purple wire connected to and briefly touch the terminal with this live wire. As you remove the wire, the spark plug should spark - this is how the low tension and high tension works on a coil, as the collapsing 12v voltage causes the high tension to dump it's voltage through the spark plug. The CDI just provides a digital 12v signal to the coil to make it spark, just as if an old set of contact breakers was working.

If you get no spark at the plug, then it's likely that the coil is defective. If the plug does spark, then we need to track down an electrical fault.

 

@ Merlin thanks for all ya help. very helpful , hopefully @ SteveP can help

 

This might help. It's for 50cc models, but it's good information.

 

i cant get the bike running so i cant do them tests. in the video

 

going to try the purple wire thing you said to do merlin , so i take a wire from the battery to the purple on the coil... and see if my sprak plug sparks....

 

Is yours a single wire or a three-wire coil? If it's a single wire coil, then my suggestion will work. If it the three-wire version, then it needs a signal from the pickup on the stator to make the coil fire. Let me know which one you have before we go any further.

 

IM CONFUSED THERES ONLY ONE PURPLE WIRE COMING FROM THE CDI TO THE COIL THE OTHER WIRES FROM THE CDI GO TO THE STATOR I THINK THATS WHAT I DID THE RESISTANCE TESTS ON