Motorcycle Repair: 1987 Honda VT250F, honda vt250f, jumper cables

Question
Hi Rich

Hoping you may have a few ideas about an electrical problem I'm having with a newly inherited Honda VT250F "Wing Special Edition".  It's a 7/87/88, chassis number MC08 4100406.

By way of brief background - the bike has been stored in a shed for the last five years and not been running.  I inherited it about five weeks ago and since then have spent some serious shed time cleaning it up, getting things like brakes, clutch, cooling system etc running again.  It starts up easily (when attached to my car battery by jumper cables to the bike battery terminals) and sounds pretty sweet despite not having cleaned out the carbs yet.

The problem is this.  The bike just doesn't want to generate its own power.  It runs well when hooked up to the car battery however as soon as the jumper cables are disconnected from the bike battery terminal it splutters and stops.  It's not generating its own power once running.  

In terms of relevant parts and testing - the rectifier is new and testing with a multimeter indicate it's working.  I've taken off the altenator cover and the altenator also tests as working.  The voltage regulator tests as working also.  I've gone over the entire bike and re-earthed it all to ensure that's all as it should be.  The battery is pretty old and dodgy but I would have thought that once running it would still sustain enough juice to keep the bike going under its own steam for a little while as running the engine should by rights charge the battery.  When the bike runs when connected to the car battery the lights, indicators and all other electrics work perfectly - no twitching or flickering.  One thing worth noting is that someone has cut the three yellow wires which come out of the altenator at some stage (obviously not realising that you can remove the plastic plug on the end) and has re-soldered them.  The work isn't pretty but the solders offer enough contact to allow the altenator to work.  What I'm wondering is whether the wires could possibly have been soldered back incorrectly thereby mixing up the flow of energy out of the altenator and into the rectifier/regulator.  

If you have any ideas I'd be really grateful.  My manual doesn't offer much info past electrically testing each component and they're all testing sound.  I'm at a loss!

Thank you very much for your time!
Sarah

Answer
Sarah, it sounds like you have already checked the electrical system. The charging system needs a charged battery to be able to check the voltage output.  If there's any charge in the battery, I'd expect the bike to continue to run once it's started.  If the battery is dead or shorted internally, it could cause the symptoms you describe.

Regards
Rich