Modern Vespa

The Rally has been sitting for most of the last 2 years, and has not run at all in more than 12 months now. With my new garage finally finished (it was outside under a tarp that whole time) I've moved everything in there and went to work getting the scoot going again. I changed the gear oil just because I have no idea when the last time was that I did that. Looked in the gas tank - it was 90% full and I don't see any signs of corrosion. The gas looks normal - red-orange color, and no signs of sediment or anything. That said, I did not put any kind of fuel stabilizer in it, and it could be as much as 2 years old, so it will be quite stale. I can't say for sure if I ran it with the fuel tap off until it died, last time I parked it. I might have thought I was going to ride it again soon enough.

So as of now, it won't start. I put in a fresh plug, so that should be OK. One thing I notice is that the kill switch doesn't feel quite right when I flip it. What do I check to make sure that's working right? IIRC it grounds the coil when you kill it. If it's not that, I guess maybe the carb is fouled and it might need a clean. Any other suggestions?

I guess it's like a baby really, has it got air? Almost certainly. Has it got life (spark)? You can test for that. Has it got food (fuel)? Again, you can check for that by removing the fuel line from the carb and opening the fuel tap. If it's yes to all three then I guess the quality of the fuel is the next place to start. Two year old fuel is usually a bit dodgy.

If the fuel tap was closed, the fuel into the carb went dry. I would check the jets, dry fuel leaves some gunk that could clog them.

I would check 1st the basic which takes you less time - the spark plug
Pull it out and kick to see if it sparks, as you said, the kill switch may be the reason

Yep, will check it for spark tomorrow. I forgot I can just ground the plug to the case, I've actually never had to do that If it looks good, I'll try just cleaning the jets, not the whole carb?

Of course you can clean the whole carb, cleaning the jets was just a quick process to check, but cleaning the carb is the perfect way to go

Clean the whole carb. Im sure theres residue in the float chamber and passage.

While you have the carb off, check that you have fuel flow. There's a low spot in the fuel line just before it exits the frame. Ive seen that clog up from sitting.

Surely 2 year old petrol will be dead by now? I'd drain every drop of fuel out of the tank and into a container to be used for washing parts.

I don't seem to have any spark. I grounded the plug to the motor and spun the engine. Nothing.

If I understand the wiring diagram correctly, the red wire into the CDI is for the cutoff. When the key is off, that wire is grounded. When on, it's not. However it doesn't seem to matter if the kill switch is on or off, and that always used to work. But anyway, if red isn't grounded when the key and kill switch are on, that seems to suggest the wiring and switch are ok (which makes sense as it's a new loom and it worked fine for months after I replaced it) and I should have a spark. So maybe the CDI is dead? I have the CEAB drop-in replacement for the Femsa. Is there a way I can test this?

Have you tried disconnecting red wire at junction box to eliminate any switch issues?

Good call. I just tried that - no change. I checked the resistance across the coil, I have about 1.8 ohms, so the coil isn't shorted. What else can I check?

Still need some help with this, if anyone has other ideas. I cleaned the carb jets today (didn't have time yet to pull the whole carb) but still couldn't get it going. I still don't seem to have any spark with the plug grounded to the case.

I rewired the stator a few years ago, so between that and the new wiring loom in the rest of the bike, I wouldn't expect this to be an issue with rotted wiring. Maybe the coil or CDI is dead - I've seen other posts where Rob Hodge and Voodoo mentioned you can replace just the coil on these CEAB CDIs and usually that gets them going. Maybe that's what I need to try next.

Here's a pleasant video to watch....and it's very informative!
www.youtube.com/watch?v=8VwRCAHT_XY&list=PLobZTXT9sfxPpWSukb3u0xFKS-myviVbp&index=105&t=7s

If the scoot ran when you parked it a year ago, I'd suspect you just have some corrosion at one of the connections.

The only way to reliably chase down no spark is to get out the meter and methodically test each component in the chain. Either start at the plug and work back to the coils, or vice versa.

I'm embarrassed to say I've run two year old fuel before (before I knew better). Started up after a couple of kicks, ran a bit rough for a few seconds (should have shut it down) then smoothed out. Rode around for a half hour or so, parked it back in my garage (turned off the fuel, leaned it to the right, waited for it to shut down). Everything copecetic. Next day, nothing, nada. Drained the tank, cleaned the petcock, the jets and the filter. Not doing that again. Good luck.

Yeah, I will go ahead and replace the gas before I try to start it again. But I still need to get the spark working.

I had to learn the hard way about bad gas. I dumped some old gas in my '71 Ford Highboy 4x4 flatbed. It automatically caused 4 out of 8 cylinders to go dead. Luckily new pushrods for a FE410 Merc were less than $2 each and commonly stocked at an auto parts store. Old gas is best used for washing dirty scooter parts!

How can bad gas bend push rods ?

Good question. I've been told that the octane added to gas breaks down over time. Maybe that happened here, and led to a huge amount of detonation.

Having said that, a 2 stroke scooter engine is a lot different from a 4 stroke v8. I doubt old gas would do that kind of damage to a scooter. I think for the Vespa it's more likely that it will run like shit or not at all.

Somehow jam up all the intake valves ?

Yes, is was caused by sticky valves. Apparently old gas doesn't lubricate an engine as well as fresh gas.

Of course an old v8 is way different than an old 2T engine, so there wouldn't be any sort of damage like what happened in my truck's engine. And like you said, a scooter will likely run bad or not at all...but, i'm betting that there's a better chance that it could cause a piston to seize up with bad gas. Reason being is that old fuel isn't going to lubricate as well as fresh fuel. So it would be best to adjust timing and jetting to match whatever fuel grade your using. It's simple enough to drain the fuel from a scooter's fuel tank, so why take the risk?

Swapped in a Ducati CDI and now I have spark! I still need to add the RC circuit to get the timing right, and modify the old mounting bracket to hold the new CDI. But it's progress 😃

lets see some pics!

Congrats and I think you will have it running again soon. I think there are a couple of different ways to wire in a Ducati CDI, what circuit did you use and please tell me more about the RC circuit? Thanks.

Based on my reading of http://www.vespa-klub.dk/Rally_CDI.HTM and http://www.scooterrescue.com/femsatronic-to-ducati-cdi.html I understood that with the Ducati CDI wired up without any modification, you should get a spark, but the timing will probably be wrong. So my first test was just to hook it up and check that I got a spark with the new CDI. That would confirm that the old one (or the coil) was the culprit. So as per those pages, I just hooked up the green wire to the red terminal, red wire to the green terminal, and the yellow ground lead on the Ducati CDI grounded to the chassis ground lug where the black ground lead from the stator also attaches. That's all I needed to get a spark.

Now I will add a 1k resistor and a 1uf capacitor in parallel per the circuit (this is the RC circuit I referred to) to make sure the timing is correct. I have leaded parts for those on hand, so I will just wire them into the circuit, not create a board like Jan did.

All good! I wired up the RC circuit, and then after draining the two year old gas and putting in a fresh tank, it fired right up! Like I just parked it yesterday! I put in new gear oil, aired up the tires, adjusted the brakes, and then took it for a ride around the neighborhood. It ran great. So nice to finally have it back on the road.

Still want pictures.

I had a sprint Veloce sitting on my shed with an almost new LML engine for 3 years. The first thing that I had issues with was the clutch/clutch basket. What I found also problematic is the fuel lines/carburators making the premixed fuel like syrup after a while.

Basically what you have is originally the fuel and 2 stroke oil properly mixed but as you don't use the scooter the fuel sort of start evaporating and the oil turns into a syrup like, too thick and it starts getting clogged. If you don't use it for a long time eventually it solidifyies clogging even more passages.

I highly recommend buying a 1 gallon chemical dip. They sell it on autocrats stores and it is basically a big 1 gallon metal can with a strong chemical and you just pout the carburator inside for a while and it dissolves all the hard deposits.

Other things that suffer are the rubber seals. I start all my scooters either daily or every week, I ride them around the neighborhood. One of the worst things that happens is when I leave my fuel valve open. Typically it floats the carburator and it takes 30-40 kicks to start it so definitely close your fuel line EVERYTIME!!

Obligatory photo...

You can't get those 1 gallon parts dip buckets in Australia, I had one when I lived in SF.

Luckily the Rally is automix so I don't have to worry about the fuel/oil evap problem. I'll go over the gaskets and things if needed but it seems to be running great now.

You might wanna check your float valve, it seems like it's probably leaking at least sometimes. Shouldn't be like that.

Swimming against the tide here:
I know this is recommended as the right thing to do, but I won't do it unless I'm leaving the scooter for long while over a week or so. My reasoning is this: the float valve when operating properly will shut off the gas and no flooding or leakage will occur. If it's flooded when I go to start or any drips next time I use it, I KNOW it's time to service the float valve, likely replace the needle(be sure it's RED and preferably the spring loaded type) and possibly burnish the brass valve seat.

I recently found a small puddle under my AllState which had been running a bit rough, starting hard. New needle fixed it & I burnished the seat for good measure. A leaky float valve will affect your fuel/air ratio and throw off your tune. If I closed it every time I'm not sure how soon I'd even know I had a bad float valve.

I've only ridden a couple of times with the new CDI, but yesterday I noticed that the insulation on the ground lead has split right at the box. Maybe this connection to the chassis is too short for the movement it sees. Thoughts?

That ground wire on P200s is typically ground under the fan shroud bolt next to the CDI. That looks like a long stretch where you currently have it ground.

Thanks, that's exactly where I was thinking about moving it to. Just wasn't familiar with the mounting and wiring on a P, since this is a Rally conversion. I'll give this a try. Glad I noticed before the wire completely broke, that would have been a pain to repair.

Good catch before it snapped!