If you have a VOM multimeter , the best way to determine a loose connection is to check the cranking voltage. With the negative lead grounded at the atarter and the positive on the output of the solenoid crank the beast over. Anything less than 10.5 volts is too low,indicating either low battery voltage or high series resistance. The next steps will narrow it down.
If the reading is low do the same test with the meter across the battery. If the voltage is close to the low reading at the starter it is most likely a battery problem. Either low state of charge or high internal resistance. If the voltage is a volt or two higher at the battery than the starter, there is a high resistance connection between the battery and the starter.
Sequentially work your way down to the starter leaving the negative probe on the battery negative ,check the voltage at the input side of the solenoid ,the output side of the solenoid (yes again) and with the POSITIVE probe check the voltage TO GROUND AT THE STARTER. If you find the voltage drop at any point the problem is now isolated between that point and the battery. A reading of over 1.3 volts between the battery negative and the ground at the starter indicates a poor gound on the negative side . Since you are now reding the voltage DROP across two points in the circuit.
A little work with the meter shoul quickly isolate the problem.
I take mine anywhere without worrying WITHOUT disc brakes ! But then again I never worried on ANY bike ,even the BRIT bikes with LUCAS electrics !And they NEVER let me down.At least since 1966 !
1969 V700 Euro 1972 Eldo LAPD 1993 Cal III Fuel Injection 2003 EV NEXT YEAR !!