749 engine removal

So my spray from RS paints turned up yesterday, its a realy good match to the original, going to leave it harden up for a couple of days,then start the rebuild over the xmas holidays
 

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Hiya folks,so if anybodys interested ive finally got round to putting it back together! Ive hit a bit of a stumbling block lol, everythings connected up bar the petrol tank, switch it on and the only things working are the parking light/ rear light hmm, checked for good earth and i have continuity between my battery neg and everwere ive checked, the only thing ive stumbled on is i have 12v into the ignition switch and 7v out when turned on! Any ideas/pointers? Thanks
 
Resistance in the ignition switch/barrel will cause a voltage drop.

I don’t have a wiring diagram to hand at present but from memory is there an earth lead which has to be connected to the ECU in order the ECU can find a ground?
 
bucko1963 said:
Bit more info, the petrol pump primes when i switch the ignition on, also if i bridge the starter solanoid the engine cranks over
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Then it’s the voltage drop at the ignition switch that’s the problem, 7V won’t be enough to switch the starter solenoid into its contact position.

When you say the ‘ignition switch’ do you mean the RHS switch gear or the key barrel? Hopefully the former as you can’t get inside the key barrel to clean it up.
 
Its the key switch mate its strange as ive tested the switch as per the manual and everything checks out ok! I bridged the connector going into the ignition using the 12v in socket and my speedo/cluster lit up! Im leaving it alone tonight as its hurting my head thinking about it lol
 
bucko1963 said:
Its the key switch mate its strange as ive tested the switch as per the manual and everything checks out ok! I bridged the connector going into the ignition using the 12v in socket and my speedo/cluster lit up! Im leaving it alone tonight as its hurting my head thinking about it lol
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That’s a bugger 😕.

I had a bike here once with a similar issue, admittedly an old 1980s Moto Guzzi with a fairly simple key/ignition barrel set up which made life easier. There was only 1-2v being passed. In this instance the key barrel was easy to access and disassemble (although even with this you weren’t supposed to disassemble it). Yes, it passed a continuity test but as soon as I managed to open it it was obvious why only 1-2V was being passed.

Unfortunately, after cleaning off all the corrosion the contacts inside the device had eroded to the degree they didn’t always make sufficient enough contact so a new key barrel had to be sourced.

The cause in this instance was due to water ingress over the years via the key entry point because a) the bike had at some stage lived outside in all weathers and b) the small flap which is supposed to spring closed when the key is taken out was broken and didn’t close hence rain could easily get in.

Hopefully this odd Not the situation with yours as the key unit on your is much newer and consequently much more secure but in a situation where there’s 12V into a switch/connector and less than 12V out it’s usually due to corrosion causing resistance which causes the voltage drop.

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Thanks for the reply mate, i might have a go at opening up the barrell, i mean what could possibly go wrong lol, theres two security screws underneath,il drill them out and see what falls out
 
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