Can anyone offer some advice to me regarding the wiring of a Sunbeam twin scooter, I believe that I have it wired up correctly although when I try to start it after a few minutes with the ignition on, the temporary earth lead I have fitted heats up and if left runs the battery down, I do have a solid state rectifier and was wondering if this may be faulty, causing the problem, or whether I have it wired up wrong.
Any sensible suggestions heeded to, its a challenge.:-)
TTJohn
The wiring on the Sunbeam scooter is fairly standard for a BSA twin, except for the starter motor if you have one fitted. Does the temporary earth lead heat up with the ignition on but without the engine started - or does it only happen with the engine running? When you say a temporary earth lead, is this between the battery and frame and is it 1.5 mm sq cable or 2 mm sq cable? If the lead is getting hot it would be interesting to know what the current is flowing through it if this can be measured.?
First thing to rule out are the connections. Are they tight? If not a loose connection can draw significant current draining the battery quickly. I had the problem a few weeks ago on my Royal Star and the earth lead from the battery was loose and got fried.
Just had the Avometer on the + side of the battery and it was drawing 6v 3amps when the ignition is switched on, so it seems like I've really got a problem there, not sure it may be the solid state rectifier up the creek, I'll have to try another one tomorrow now. I am using he original harness and I've just put two new 6v coils on it.
The 6V ignition coils should each have a resistance of 1.5 - 1.8 Ohms and draw just over 3A with the contact breaker points closed which seems to be the case here - this is perfectly normal. However, if this is the current flowing through the temporary earth lead then it should not get hot.
Thanks all for he replies on this issue, I have now sussed it, put on a new earth lead and as you say Spaceman the 6v 3amp is normal, so I did manage to get it started yesterday although the carb is not so good and could do with replacement, it has a 17mm Zenith carb which is the correct one for this bike and the size is critical, as there's not a lot of room in there for anything different (unless you know better) any suggestions welcome.
TTJohn
As said previously, the 17 mm Zenith MX carb was also used on some Tiger Cub models which alternatively used a 17 mm AMAL 332 carb. Although you can't seem to get any new Zenith spares from Burlen, you can get some from the main Tiger Cub spares provider:
https://triumphtigercubspares.co.uk/product-category/zenith-carburettor/