Modern Vespa

OK took the wife's lxv for its MOT yesterday.all was well untill about half a mile from the test station and it just died. Totaly geared up, proper jacket kevlar trousers helmet and gloves had to push it.
Who would believe in Scotland a hot and sunny day in may? (and at the weekend)

Anyway
the scoot works well when cold, as soon as it gets up to temp as soon as you start to rev it, it cuts out.

its not fuel starvation.
its a 125 carb modle the last of the line.

I cleaned the carb about a month ago, I had to replace the fuel lines as they were perished. The jets were perfect. the only thing I have changed since then was alter the idle as its new belt was slapping against the case.

so the symptoms are when warm as soon as you rev the engine dies. It starts easy and idles.as soon as you blip the throttle dead.

Any ideas?

On the bright side it only failed on a front wheel baring and head light alignment. so at least it will have an MOT when I pick it up. (In the UK not riding is not a fail, I suppose how safe can a non rider be?)

feckin vespas!!

How long has it been since the valve clearances were checked?

What model year?

Its a 2009 2 valve LXv 125

it's not the i.e. model.

the valves were set about 2000km ago

Fuel, Air, Spark, Compression. When it dies can you confirm spark? On the vintage scoots old failing CDI's will work cold and then once you get moving they can die. Wait 20 minutes and itll fire back up on you.

Sunny weather in Glasgow, the poor wee things in shock!!!

even when warm it will sit at idle.
Its when you give it throttle is splutters out.

If I raise the throttle gently and slowly the revs increase until a point then its starts to splutter and die.

If I give it a quick blip it dies immediately.
if I then press the starter it idles away quite happily.

Are there different jets for idle on the modern vespas?

How about checking for an air leak between the carb and engine or possibly a loose ignition line/wire on either the low or high side.

When you did the carb work, did you take off the carb? What else did you touch?

Sounds like riding (vibration) finally let loose something you forgot to tighten.

2009 lxv 125 carb problem (another one)

this is what I did
but it seemed fine after.

since then I have done about 60 miles.

I'm not sure about the MV setup, but I had a VW issue where the timing was not advancing properly. Timing?

I learned a long time ago (thank you VW Bus) to never assume the problem was something I did, but also to never assume that the problem WASN'T something I did. I know that sounds a little silly, but many moments of clarity have occurred for me with the removal of the natural inclination to make any assumptions.

The rest of this post is purely anecdotal and has no bearing on your issue whatsoever, so feel free to skip it.

VW valve adjustment was every 3000 miles, and I was familiar with it. I spent an hour under the Bus doing what I do and when I was done I had the hardest time starting it. I had to give it all sorts of gas to keep it running and moving it resulted in the mos horrible backfiring and popping ... obviously I had done something wrong. So I went back through the whole procedure using different gaps listening for change and there was no noticeable effect, no matter what I did. I was working second shift at the time, so I drove my other car to work and over the course of the next few days I spent hours with my manual and tools trying to figure out what had happened. Long story short, I had accidentally bumped the wire leading to the electromagnetic cutoff valve on the carburetor and that was the entire problem. I plugged the wire back in after crimping the connector a little to eliminate the looseness, readjusted the valves and everything was hunky-dory. I had made the assumption that it was a valve problem because that's what I had been working on.

Another time - same Bus - I left work (still second shift) and when I turned on the headlights they both flashed and went out. It was dark, so rather than work on it then I put my flashers on and drove home by the most well lit route. I checked fuses, replaced the switch checked wiring, and the last thing I did (which should have been the first thing) was to check for 12 volts at the headlights. Sure enough, 12v. One of the bulbs had blown and the current spike had taken out the other bulb. Both had burned out simultaneously. I had made the assumption that the bulbs were good and something else must have gone wrong, because what were the odds of both bulbs burning out at the same time, right? Pretty high, I learned later.

So, yeah. No help there at all. Best of luck with your issue. Hopefully it's something simple.

I cleaned the carb about a month ago, I had to replace the fuel lines as they were perished. The jets were perfect. the only thing I have changed since then was alter the idle as its new belt was slapping against the case.

Fuel line crimped, routed wrong or collapsing when fuel demand is increased?

I was thinking the same thing. Had a similar issue (vapor lock) because of the breather hole in the gas cap. Same symptoms...

Can you smell fuel coming from under the seat? What state are the plugs in?

Sounds like your CDI is going. Good call MJ. Mine did that. My '07 LX 150 would fire right up when cold, then once it would warm up, it wouldn't start. I'd have to let it cool down for about 20min before it would start again. We changed out the fuel tap, redid the lines and some other things. Finally the only thing we didn't do was change out the CDI. I had one in my LT 150 so we took it out of the LT and put it in the LX. Started right up and has worked fine since we did that in 2014. You can get a new CDI much cheaper than what i would of had to pay 4yrs ago if i hadn't had one on the LT. Give George at Scooterpartsco.com and he can hook you up with a new CDI He's got some new ones for cheap. Good luck. When you get it fixed tell us what the fix was.

"Ya worked on the feckin thin, no wonder she no works, Captain!"

Yeah, I figured it would have been safer than working on the PX!

ashbrook - that was the reason for the fuel pipe replacement

cballweg - I was careful with the pipes (even replaced the fasteners)

but certainly worth a second look.

Its bloody typical though, this is the 4th day on the trot with no rain. To those who are not familiar with Glasgow that's about 25% of the sunny days we get in Summer.

Give that and the bowl a once over. If it's all good check the rubber diaphragm. Rubber might be getting old.

I would change the CDI, it's easy to swap out.

If it has a choke it sounds like it is stuck closed. Had a lawnmower that did exactly the same thing