CB250NB electrics

Welcome to the forum!

Are you sure you have the right bike? There are no fuses in the area of the solenoid- the fusebox is on the LHS on the regulator/electrics plate. With different colours in and out to those.....

There is a 30 amp fuse on the side of the solenoid on some models with a four pin connector block but the corresponding connector on the wiring loom I have was all rotted and in bits. It is or was what looks like a red connector block with four wires coming out of it that joins onto the main loom. The solenoid itself is OK.

normalbillet seems to be referring to the other side graham- where the solenoid is connected to the battery? Must admit I have never seen a fuse in this area on any model of SD- but who knows and a photo of this fuse/solenoid would be interesting?

could be an aftermarket solenoid with a fuse something like this

www.ebay.co.uk/itm/NEW-12V-STARTER-SOLENOID-RELAY-SWITCH-HONDA-FUSED-FUSE-30A-35850-MCG-00-235594-/181265629028?hash=item2a3445ff64:g:I7oAAOxy1NxSGInl

Sorry normanbillet but what mess?

To say you are conFUSING us could be and understatement.
Bung a picture up mate - it will paint a thousand words and help us to help you.  

Picture showing - excellent!!!

You should have what you need to work it out from grahams photos and diagram. But your wiring and bike look very non standard (no airbox?) so we can only tell you how it originally worked!

Assuming you have the main supply to the starter motor coming from the battery +ve terminal to one lug, then the other big black lead from the other lug down to the starter motor.

From your photo you seem to still have the original twin white connector that you can also see on grahams photo. These are a red and red/white in a short wiring tail connected to the permanent live lug of the solenoid and are the main feed across to the fusebox on the other side- the 10A fuse which are the reds in and out on the right of the large red connector at the base of the rectifier plate. This fuse in turn supplies everything else on the bike through the ignition switch and the other fuses. On some bikes the red/white goes straight to the rectifier and changes back to red and it seems to change randomly as to how the reds and red/white are connected through to the fusebox and/or regulator.

The only other connections to the solenoid are then the +ve and -ve to operate the solenoid coil, close the main contacts and spin the starter. Originally these were flying leads off the Honda coil with the yellow/red (+ve) ending in a male bullet connector and the green/red (-ve) a sleeved female bullet connector. These then connect into their respective connectors in the main harness. You seem to still have these 2 coloured wires into that red connector in your photo- which I assume is meant to plug into your pattern coil? The red and green wires you have are extra- maybe someone has used that 30A fuse you have to supply the rest of the bike. I mean- do you still have the original fusebox on the other side?

The yellow/red is easiest to figure out- as I said it is the +ve feed to the solenoid coil and goes back to the starter pushbutton in the RH switchgear.

Green/red you may have to spend some time on though- depending on the state of the diode, neutral switch and clutch switch system? You might not have these any more, but I put up a guide on how it all works a while back if you can find it. Originally the starter circuit was completed- when the pushbutton was pressed- by the green/red (-ve) from the starter solenoid coil splitting and going to the starter diode (on the rectifier plate and visible in grahams photo as the white connector/black component) AND the clutch switch on the LH switchgear. Still as green/red and if the clutch is pulled in the circuit is allowed to earth and complete through it. Alternatively- from the other side of the starter diode- in the forward driven direction for the diode- a light green/red cable goes to the neutral switch so the circuit can complete if the engine is in neutral. The light green/red also goes to the neutral light in the console, which is why we need the diode..... If you don't have all this stuff then maybe your green is just a simple earth for the pattern solenoid?