Honda-SOHC

Is that Noel Edmonds on the front cover 

http://blacksquaremotorcycle.com/electrical-system/

http://motorcyclemd.com/how-to-fully-troubleshoot-your-motorcycles-charging-system/

To check the stator measure any 2 yellow wires resistance, should be fairly low ohms (bike not running)
Any yellow wire to ground should measure open circuit.

Bike running, any 2 yellow wires, AC volts around 20v upwards depending on engine speed.
If the meter reads a few milli volts AC on any 2 yellow wires the stator is working, the exciter coil is not, check the voltage (DC this time) to the exciter coil, between white and green wires or white to ground. (this was on my 550 so colours may be different)

I was convinced for ages my stator was faulty on mine, turned out to be a break in the wiring to the exciter coil.

There is a tank on eBay at the moment.

My head gasket is weeping oil and getting worse although the bike still pulls like a train.

Where is the best place to get from, any makes to avoid?

Could i get away with just changing head gasket or will removing the head disturb the base gasket?

Thanks.

I just replaced the fork oil in mine, made a huge difference.

Sent you a PM

From the following website:
https://www.check-mot.service.gov.uk/


 UJE312S HONDA CB750


Colour Red
Fuel type Petrol
Date registered 31 December 1978
MOT expired on 15 April 2014

Get an MOT reminderwhen the vehicle's MOT is near its time for renewal. (Opens in a new Window) by email or text.
If you think the MOT expiry date or any of the vehicle details are wrong, contact DVSA.

Check mileage recorded at test, MOT expiry date, defects and advisories
The MOT test changed on 20 May 2018

Defects are now categorised according to their severity – dangerous, major, and minor. Find out more
Date tested 16 April 2013
Pass
Mileage 15,738 miles
MOT test number 5883 0620 3108
Test location unavailable until further notice
Expiry date 15 April 2014
Advisory notice item(s)

    Front Roller brake test indicates a slightly grabbing brake (3.3.A1b)

What are advisories?
Date tested 5 March 2010
Pass
Mileage 15,677 miles
MOT test number 8801 9466 0095
Test location unavailable until further notice
Expiry date 4 March 2011
Advisory notice item(s)

    Steering movement slightly 'notchy' (2.2.1b)

What are advisories?
Date tested 16 June 2007
Pass
Mileage 14,060 miles
MOT test number 6740 8766 7199
Test location unavailable until further notice
Expiry date 15 June 2008
Advisory notice item(s)

    Steering movement slightly 'notchy' (2.2.1b)
    Rear Brake lining(s) close to minimum limit (3.2.A1f(i))
    Front Brake hose slightly deteriorated (3.2.B3b)

What are advisories?
Date tested 16 June 2007
Fail
Mileage 14,060 miles
MOT test number 1810 4736 7188
Test location unavailable until further notice
Reason(s) for failure

    Nearside Handlebar handgrip not secure to handlebars. (2.1.1c)
    Headlamp aim beam image kick up to the offside (1.6)

Advisory notice item(s)

    Steering movement slightly 'notchy' (2.2.1b)
    Rear Brake lining(s) close to minimum limit (3.2.A1f(i))
    Front Brake hose slightly deteriorated (3.2.B3b)

What are failures and advisories?
Date tested 4 May 2006
Pass
Mileage 13,613 miles
MOT test number 6243 5432 6102
Test location unavailable until further notice
Expiry date 3 May 2007
Date tested 4 May 2006
Fail
Mileage 13,613 miles
MOT test number 2245 1432 6478
Test location unavailable until further notice
Reason(s) for failure

    Steering headbearing has excessive free play (2.2.2)