Modern Vespa

OK, so when I was trying to get my P200E, 1980, running reasonably I found that the green wire from the CDI to the front was deteriorated. This is the ground wire that the ignition switch and the kill switch use to stop the motor. I replaced the wire by running a wire parallel to the harness and changing the connections. So today the ignition switch would not stop the engine. So I hit the kill switch, and that would not kill the engine either. So I know what the problem is, I can fix it, no problemo.

But there is another problem. My new battery loses its charge over a number of days.

My question is are the two things related?

The ground wire seems burned up. Does it carry a heavy current load at shut down?

How much hassle is it to change the wiring harness? Do I have to disassemble the whole thing or is it pretty much just a connection issue?

The gas tank removal is trivial, and I have pull cords through the chassis to pull wiring, so should I attack the whole harness or just the ground wire?

First I couldn't keep it running, now I can't make it stop.

I had a similar problem in a car at one point. My '82 Pontiac Grand Prix (land barge) ate through two ground wires that simply went from the battery to the frame. We never figured out why it was doing that though. Dad just got a super thick piece of wire from something else he was working on and hooked that to the battery, there was no way that was going to get fried up. The thing ran like a tank from there on out. Sorry I can't be more help with what you should do, but sometimes it helps to know you're not the only one in the world that's had to deal with it.

I sort of sounds like you are grounding out somewhere. Electrical issues are a pain. Get a voltmeter and start checking.

If you have the time and inclination to run a harness, do so. you could spend hours and hours trying to track down wiring gremlins and never get it correct.

Your battery could be losing charge due to faulty wiring, or it could just be an old battery. Once they are past their prime they don't charge fully and gradually won't charge at all.

Easiest way to run the harness is to start in the tank - throw the wires to the back to the back, and then throw the wires to the front up to the horn casting opening and stop there.

THEN run from the horn/fork opening up into the headset. Trying to pull all the way from the tank area to the headset is asinine.

Leave the wires in the headset connected to the old harness, once the new on is in place you can then connect them without screwing up which wire goes where.

Good advice, Mike. Sorry, I had to give you a thumbs up on that one, even though I know you prefer it the other way.

Damnit!


Can you give me negative karma because I forgot to mention that the wires to the stator can also be going bad and he should pull the stator and check/rewire it when he does the harness?

Though really some muppet will come in and give me bad karma simply because they don't like me hanging around being mean.

ATTGATT!

I think you just found Airborne's MV avatar...

AWESOME!

Mike, you totally have to use that pic as your Avatar. Be careful though...you are slowly becoming a part of the community here.

Before you know it, Mickey will be back here.

put the front wheel against a wall pop it in 1st and drop the clutch ...... simples

Thanks for the tips, I'm past most of that. When I was trying to get it to run reliably I had the stator checked out twice by the guru at Motorsports (Robot?) I ran a new ground wire from the screw on the engine and rear junction box to the box in the horn cast. The ground/kill wire is still the original from that junction box to the switches in the headset. The battery is new.

Failure to stop is a *failure* to ground; if it was grounding it would stop the engine. This feels like a broken or intermittant wire. The wire I was bypassing was badly damaged, brittle and melted looking insulation. When you turn the bike off, does the ground wire take a great surge of current? Maybe I should just put a huge honking wire in there, about 10AWG.

How hard is it to run the harness from the tank to the horn cast? I guess I'll just grab the multimeter and start tracing.