random issue

[dann]

Hi all,

Bought a nc 30 off a friend, its a great bike but has a random problem...

starts fine, rides ok for maybe a few miles, then looses all electrical power, lights dont work, wont start,... leave for a few hours and it'll start first time again!

sorry to be vague, but looking for ideas,

thanks

dan

[gonzothegreat]

I would remove the seat and check all electrical connections, had a similar (ish) issue and it was just a loose connector.

[CMSMJ1]

Sounds to me like classic reg/rec failure.

The battery will ont be taking a proper charge and so you'll need to find out if it is the reg/rec or the stator not working right.

An easy enough fix and a common enough problem.

Check the battery voltage with the bike off, on and also at 5k revs.

Let us know.

Howdo too...whereabouts in |Derbyshire are you? I'm on the southside of Sheffield...literally half a mile from Derbyshire

[dann]

tried a rec off my friends other nc and still got problem? im starting to think maybe coils or stator breaking down expanding when hot, creating a short, then contracting when cold and no problems,

does this sound feasable??

dan

[uber pikey]

I did have a simular problem with an old DT175MX(check me out) the coil and lead were old and broken and as they got hot they would arc across the engine, leave it for 15 mins and fine again. Dont know if this is the same issue but hope it helps.

[Neosophist]

Have you tested the electrical system?

It is possible for it to break down under load whilst hot.

It is best to check it first generally..

Measure:

(Following in DC volts, 20 if your meter has ranges)

Battery voltage with ignition off

voltage at the battery at idle with lights on
voltage at the battery at idle with lights off

voltage at the battery at 5000 rpm with lights on
voltage at the battery at 5000 rpm with lights off

(Following in AC volts 200 if your meter has ranges)

Disconnect the plug that goes from the generator to the reg-rec that has the three yellow wires on it.

Call them A, B and C

Meaure voltage between two of the 3 wires at 5000rpm in the following order.

A & B
A & C
B & C

Turn the bike off and measure the resistance between the above wires with the multimeter set to Ohms (if it hsa a scale make sure its at the smalest)

Before you measure connect the red and black leads of the multimeter together and note the value, if it isn't 0 you need to take this number away from your reading.

Then finally measure between the A,B,C wires and earth on the same setting, these 3 combinations shouldn't have a reading.

[Man_Named_Dave]

When this happened to me I had a frazzled generator and burnt-out reg/rec.

[viper61]

I had a similar problem and thought it might be the coils but in the end I found the connections on the ignition leads between the caps were all a bit suspect, so got some HT lead from Rick Oliver and re-did them all my self. Since then bike's been perfect.

Perhaps check the resistance of the coils and leads and see what that turns up as well as the other tests.