Modern Vespa

I have a 2005 PX150. Last week on my way home from work it sputtered to a stop, loss of power. Fortunately I was a block a way so I pushed home. I thought that I was out of gas, but when I checked the tank was half full. I checked for spark no spark, so I replaced the plug, no spark, I checked the spark plug wire and it has continuity. The scooter has been running kinda hot lately so I thought that I might have burnt out the CDI, so I replaced it, no spark. I then replaced the stator, no spark. What should I be looking at next?
Any suggestions? Thanks

What about the dreaded short of the green wire (engine cutoff)?

I broke mine last year, but had the opposite problem, I couldn't shut off my scooter.

Is that the green wire that goes to the CDI with the little white clip on it? How would I test it?

The green wire goes to the kill switch. If it's grounded to the frame somewhere you cannot see it, you'll get no spark.

Check if it has continuity to ground.

Or remove it and see if you get spark.

Common problem with Older P series and Stella

Thanks I'll try that

you might also need to check your stator if the Green wire is good. You could have a broken coil or wire that will kill your spark

Or a new, low km LML

What order did you put the stator wires into the CD? It should go white, red, green and then green with the square, white plastic insulator around it. If you follow it up, it goes through your junction box and up into your harness.

If you get a multimeter you can test the stator coils. Scroll down to where it says PX150

Stator Values Wiki

If everything checks out and you still get no spark, please add some pics showing your stator insulation and harness wires. CDI's you can't troubleshoot since they're all internal. Last thing I could think of would be a weak flywheel.

Ok here is the latest on my no spark issue. I decided to start at square 1, so I disconnected all my wires and took off the flywheel cover and started to remove the flywheel nut. That's when I noticed something really wrong, the flywheel nut turns separately than the flywheel, before when I took off the flywheel I had to put a long screwdriver in an area to stop the flywheel from turning so I could get the nut off. Now when I turn the nut the flywheel doesn't turn but the nut does. I think that I sheared the shear pin. So how do I remove the flywheel? Please help I'm about ready to push this PX over a cliff!

On a PX the nut comes all the way off and then you need an extractor that screws into the flywheel. Do you have the M28x1 extractor?

The good news is that if you're really spinning the flywheel on the crank, you can get it off without an extractor.

When you re-installed it, did you torque it to spec (45 ft-lbs, iirc) before kicking it over?

If you've sheared the woodruff key, you'll need to replace that. I ordered 10 of them one time because I have had some bad past experiences in that department, so of course I haven't sheared one since.

if the keyway is chewed up, that'll make getting the timing set exactly more difficult, but loss of spark is usually either the CDI or one of the ignition wires rubbing and grounding out on the motor.

Hey guys thanks for the replies. I do have an extractor, and used it last week to take the flywheel off and replaced the strator. The problem I'm having now is when I go to take the nut off the spindle the spindle and flywheel turn separate. So I think I might have seared the woodruff key.

Ok I think I'm getting it now. Got any impact tools? Got a neighbor with some? It'll buzz right off with the right tool.

Otherwise, you need to lock the crankshaft so it doesn't keep spinning. Try jamming some rope down the spark plug hole in the head and then unscrewing the flywheel nut again.

And PSA for everyone, please upload pics anytime you have problems. It eliminates any terminology/language barriers and let's us solve and help much faster.

Thanks for the reply. Do you think putting it in gear would work? If not Ill try the rope, but then again I wouldn't mine getting a compressor and some power tools.

Nah don't put it in gear. Just jam the rope down the spark plug hole and let the piston compress against it as you unscrew the flywheel securing nut.

If you put it in gear everything locks, but the weak link are the clutch plates. They'll eventually give depending on the torque you'll be applying. It's better to eliminate everything and just keep the crankshaft locked without engaging anything else.

I use an impact driver to get the nut off and it works great.

To re-install, I use a big flatblade screwdriver. I stand it on the floor, braced against a flywheel blade and the kickstart entry into the engine casing. Hold it aginst my boot and torque away.

For some reason, every time I've ever ordered a flywheel holder, it was on backorder and now my technique is good enough, I don't even miss it.

You heathen!

Hah!

What's funny is that I have all the seriously specialty tools, like crank pullers & presses, bearing pullers, etc., but don't have a flywheel holder, which is probably the most common specialty tool out there other than maybe the flywheel remover itself.

Getting back on topic...

The woodruff key on the crank is for locating the flywheel on the crank for proper timing alignment. The pressure of the flywheel onto the taper of the crank is what holds it in place.

They're cheap enough that you might as well order a batch of 'em so you'll have spares if you do it again.

Also, I noticed that Home Depot had a drawer of woodruff keys in the specialty fasteners rack, so I may see if they have one that's a match for future reference.

Is the keyway still in good shape, at least?

[quote="MJRally"] I wedge a screwdriver (or whatever is close by & fits) between the flywheel & the casing, tighten flywheel l itts, tighten the nut further, then hope I can get the screwdriver out without undoing the nut! But I'm a butcher! However, even using 2 (or 3) big screwdrivers as a flywheel puller I've NEVER SNAPPED A FIN, as always put them under the strongest point. Hmmmmmmm... I wonder what caused the problem?
ALWAYS ensure the woodruff/halfmoon key is in the correct position. I wondered if it's sheared off?

I really honed the Big Ass Screwdriver method when I had the flytech, which has plastic fins, and never broke one of those.

With an electric starter ring, you can just jam a screwdriver into the starter gear teeth and brace that against the engine case. That's the easiest one of all if it's an option.

Now, we should let OP get back to his original problem.

Any update on the woodruff key? Sheared? Missing? Smeared around the crank?

If it's missing, check that it's not stuck to one of the magnets or just hanging around stuck to a stator coil.

Thanks for all the help. The woodruff key did shear.so lm in the process of trying to get a replacement. The rope in the cylinder idea worked great 👍🏻 The threads on the spindle were damaged,but I have a tap and die set and cleaned the threads up.Once I get the woodruff key installed I should be fine.

For clarification, does anyone have an idea how people are shearing these keys? I've never had this issue (knock on wood) but then again I always use a torque wrench, which is where I'm guessing the issues come in...

My personal technique is to hand-tighten the flywheel nut, get distracted by something bright & shiny, then kick the bike over at the same time as I remember that I didn't torque the flyheel down.

If the woodruff key has been sheared, there's a good chance that the slot in the crankshaft has been damaged as well. Do you have any pics that you can post up?

Here is the latest on my PX 150. In answer to the last question about the grove in the crankshaft being damaged from the woodruff key shearing, there was no damage. I put everything back together and the scooter started right up! So I took it out for a spin. I got about a mile down the road and the scooter lost power, but since I was still coasting I popped the clutch and it came back to life, but died again about a 100 feet later. So again popped clutch, start, die.i managed to get it back home by doing this and working the throttle so it wouldn't die. Once I got home I tried to start it , but it acted like it was out of gas. So I let it sit for about an hour and then tried to start it again, it started just fine but died after a minute. It has spark and gas, what am I missing?

How much gas was in the tank when it died? Were you down to the dregs? One possibility could be a dirty carb. A speck of gunk could have been sucked in from the bottom of the tank. Use this tutorial to guide you on cleaning.
http://vespamaintenance.com/fuel/carbrebuild/index.html

One other thing to check is that all electrical conections are clean and secure. Insulation crumbles, plastic holders fail, wire breaks etc. so go through every once in a while and make sure things havent loosened up.

Let us know what you find.

Try running it with the fuel cap loosened. That's also the symptoms of a clogged or almost-clogged breather. Negative pressure forms amazingly quickly, preventing fuel flow.

I tried the loosened gas cap, it didn't seem to make a difference. The scooter starts right up, but only runs for about 15 to 20 secs then shuts down like it ran out of gas.when I took the carburetor top off I noticed a lot of fuel in the bottom of the carburetor, I sucked the fuel out and tightened the oil feed nut, it was loose and looked like it was leaking.

Have you cleaned all the carb jets yet?

I went back and was re-reading your original post. What do you mean by, "The scooter has been running a little hot lately?"

how much fuel line is there between the carb and the frame ?
when it cuts out loosen the "chinese hat" on the carb top see if fuel is flowing
if its not flowing try pushing or pulling the fuel line where it goes through the frame you dont need to go mad just move a little each way to see if it makes a difference
the tubing piaggio uses as fuel line is garbage it can kink and over time goes hard