Modern Vespa

Hello All,

I've got a very strange, and aggravating problem. Today I went to start my MP3 500 and the starter wouldn't even engage. I know the brake lever switches are working just fine. I could see my brake flashers firing, so that's not the issue. I had to try pushing the starter button at least a dozen times before the motor finally started turning the engine. When the engine started it ran for about 1.5 seconds and then died. I tried the starter again and once more the starter motor wouldn't turn. Another dozen attempts later I was able to get the engine to start and this time it ran for two seconds before dying. After five minutes or so I managed to get the engine going and ride for about 400 feet before the engine cut out, and this was not at idle. About ten minutes later I got the bike started again and revved the snot out of the engine to keep it from dying. I managed to get the bike two miles down the road to get it home. Along the way it would hesitate every now and then as if it was missing a power cycle every few rotations. When I reached my driveway it died once again just in front of my garage. I tried restarting it one more time and the motor once again would not engage. A half dozen more attempts and the engine was running at idle with seemingly not problems.

Now I'm at a loss for what single issue could be causing the starter to not engage, the engine to die after starting, and the engine to misfire randomly. Any ideas are greatly appreciated as I would have to ride quite a distance to get the scoot looked at, and I don't want to risk breaking down halfway there.

The first place I would look is at the "Kill" switch. They do some strange things and will keep it from starting or kill the motor if running. Try exercising the switch several times. You can take the switch apart and clean the contacts. you can also try bypassing the switch to troubleshoot the issue. Just don't leave the bypass in place. If you do get it to run right and it is the switch, I would buy one to have for replacement. Either way put some dielectric grease in it to help keep road grime out.

That's an excellent idea. Why didn't I think of that? Must be this heat wave. Or maybe I was still flustered from that tail strike my student did an hour earlier. I'll test it out a little later and let you know.

Alright. I pulled the kill switch and cleaned the contacts. They were a little corroded, but not bad. Probably just enough to get intermittent contact. I started the bike twice to check and I got 2/2 starts. I think I'm good. I just have to remember that darn kill switch in the future.

pack those full of dielectric grease to prevent any future issues.

You might also consider Bypassing the kill switch, so as to disable it... I do this on all my bikes, because I see a lot of Risk from having a faulty kill switch... I just don't like the idea of having my bike shut off at random times in traffic (much less having a starting problem as you did).

That's two different electrical contact failures you've had in a week, both with switches on the handlebars. And both fixed by cleaning contacts and using dielectric grease.

Might be time to get preventive and clean and grease all the remaining switches and connectors before another event. There's some good tutorials on the site here.

You can't very well bypass all your contact switches. Wouldn't it be better to clean them and use dielectric grease as part of your regular maintenance? - as Bravo and OAD suggested. (dielectric grease is really the bike riders friend in my experience)

That's an excellent idea. Why didn't I think of that? Must be this heat wave. Or maybe I was still flustered from that tail strike my student did an hour earlier. I'll test it out a little later and let you know.[/quote]


What student and what is a "tail Strike"?

The problem is that I can't garage the bike all the time. It sat out in the rain for the past few weeks. Part of that time it was under a deck, but it didn't stop the rain from coming through. Tough roads and weather in the Pacific Northwest.

What student and what is a "tail Strike"?[/quote]

One of my instrument students in the Chinese flight training program, and he smacked the tail of the aircraft into the runway. Last flight of the day and I had to stick around for paperwork and a call to the chief instructor after that. Then the scoot wouldn't start. Not a great start to the week.

http://www.walmart.com/ip/Classic-Accessories-Moto-Gear-Deluxe-Motorcycle-Cover/11208786

I recommend one of these. It is vented in certain areas, and the hooks keep the wind from ripping it off. It's water repellent, and the only problem I've had with it is that the color has faded over time from the sun. But no big deal, it still has held up and I just spray it with Scotchguard water repellent once a year at the most.

This brand was the cheapest I have seen for a heavy duty cover so far.

All the more reason to grease up! That's what keeps the moisture out and significantly helps prevent corrosion, whilst also providing a little lubricity to switch function. The only downside is the grease can help dirt to collect.

Tough weather indeed, been in the 90's in Portland for days - not good for the webbed toes and mossy-eared Northwesterner.