Modern Vespa

Morning All,

Currently working on the LX50 and runs good for 5 / 6 miles, but then the idle seems to get a bit low and cuts out. I can catch it and just increase the revs a bit. I have had the carb off 4 / 5 times and it is clean, and the fact it runs for 5 / 6 miles with stopping at junctions etc suggests it should be ok. However it needs a new float bowl gasket as it is leaking a bit, as is the drain tube underneath slightly which i have now plugged to stop that happening. My question is should i persevere with this carb, or simply swap it out for something like for like as follows:

https://www.pedparts.co.uk/product/5372/dmp-175mm-phva--piaggio-carb

If the autochoke is the issue (i did turn the idle screw down a fair bit when i first got the bike, and wondering if maybe i did it too much and after 5 / 6 miles the autochoke is disabling perhaps). the above carb wouldn't come with a choke, but there are some that do for around £35 - £40. Not sure whether to just replace the gasket first, and increase the idle and see if that stops this sporadic stalling. Or just buy a new carb.

I would think the autochoke would come off before 5-6 miles? Mine starts coming down after 2 or 3 minutes and I can hear an obvious drop in engine speed. Do you hear this if you start the bike and just leave it for a few minutes?

How many miles are in the bike, and when were valves last checked? Or is this a 2 stroke?

It would seem odd to me for the carb to be main issue, if it runs fine for several miles. I'd think it's more the things that change as the engine gets hot (like valves, or air leaks in manifolds, etc)

Also rule out electrical connectivity glitches between the coil and spark plug, and a failing coil (which starts to happen when it gets hot after a few miles).

Thanks, I've since done a 40 x mile round trip to another town and back. Didn't cut out on the journey. You can actually make it cut out if you throttle hard, then throttle off and stop quickly. It doesn't cut out if coasting to a stop. At least that has been how it has presented itself previously. It is a 2 stroke. I haven't adjusted the idle mixture, maybe I should try that. Sometimes it will idle totally fine, other times if it is just sat idling it will increase a bit and then decrease.