Modern Vespa

Dear ET4 Guru

First off I'll describe what happened on each occasian

Surrey Lanes rideout
Nice Hot day, I've scooted to work. After work it's a scoot down to the meet up place. About an hour and half into the ride we stop for fuel. After fueling up I try to start Liz, but there's no life in the engine. After a chat and the immortal words "roadside recovery" Liz starts up, and we continue on.

Arrive at the meet up point turn off engine, a bit of blah blah and we're off, start up no probs.

I think after about an hour of riding. At the first pit stop, the engine has been off for about 10mins, go to start her up and the same problem again on this occasion kick starting was tried but no go, so I got a jump start and she springs to life and we're off again. No more probs for the rest of the ride. This prob did have some of the other riders stumped.


Duxford ride out.
No start up probs, off to meet up with the other 125er's. Meet up, about a five min chat and then we're off. We've been riding for less then 10mins, I need to stop for petrol and stop at a station which is closed. Less than five mins off the bike and there's the start up problem again. Eventually she gets started of the kick start (wohoo broke my kick start virginity). No more problems, even after finding an operational petrol station and filling up.


My lack of knowledge and fustrating the in house vespa padawan has got me posting in the hope a guru can shine some light on the situation. We've got a ride out planned in August and I want to get any problems sorted before then as it would be a bummer to have her breakdown during the roadtrip. Could it be the start of a major problem?

Spark plug looks fine, I'm planning on checking the fuel line (think that's the right rubbery tube) tonight. But she started fine today and I can't smell any fuel, although during the hot weather I could smell fuel (didn't see any evidence of liquid leakage), but I thought it was coming from the neighbors scoot fresh from a ride.

Does it help that on each of the rideout Liz was pretty much topped out in terms of speed so the engine would have been running hot (or very hot).

I hope this all makes sense. Liz is a pre-leader engine by the way.

Any help greatly appriciated.

so the basic problem is that she often won't start when the engine is hot, but starts up just fine when the engine is cold.

I spent hours on that essay for it to be condensed into 2 lines

I've taken the liberty of editing the title, hopefully to catch more clueful eyes.

My thoughts are that if it was a vapour lock in a fuel line, the bike should still start as there'd be fuel in the carb. However when we jump-started it there was no smell of unburnt fuel from the previous attempts. I'd be looking at a fuelling issue to start with.

The battery certainly didn't have much urge in it after such a brisk ride, but the ignition isn't dependent on the battery. The bike was just fine once started, so not something electrically intermittent.

pull the evap hose

It doesn't have one - no UK bikes have them.

i i had the same problem with my et4 pre leader, i changed the ignition switch,and battery that solved the problem,,also decided to replace the start relay later just for peace of mind. had,no probs for two years now

For the avoidance of doubt, the starter turned the engine over just fine, it just wouldn't actually start running.

But it could do with a new battery, true.

As with any piaggio engine, even the bigger stuff... its worth doing the obvious valve clearance check to make sure the gaps not far off...

Then its worth checking the autochoke unit, mainly to ensure it is actually working and fully extending and retracting. When cold it should stick out about 13mm and when hot 19mm...

It might also be worth doing putting a voltmeter on the battery and try cranking it over, as ive known the starter to get gummed up and pull so much energy from the battery theres not been enough to make a good enough spark... (leader engine only)

If its got an immobilizer as well... theres another whole host of things it could be

Thanks for all the advice so far.

I got a voltmeter to the battery a few weeks ago, although I can't remember what the numbers were they were confirmed as being ok. It might be worth getting a new one in there anyway, I'm not too sure when her battery was last changed.

Valve clearences etc, I was thinking about this some time ago before the problems were happening as I was checking out some other threads. I don't think she's had the once over on this. On the issue of taking things apart would it be worth getting the carb looked at?

Damn, it looks like the only thing I can do is change the battery. Gonna have to get in touch with the trusty local mechanic on the valve issue, or is this something I can do myself? Any recomended tools if it looks like I can? as buying the tools and doing the job would be a saving in the long run or is it best to leave it to a professional?

leave the valves to kelvin - it's not a first-time DIY job. a carb clean wouldn't come amiss while he's in there although it's simple enough to do at home. I can't remember when the battery was replaced - about two years ago i think, after i drained the original one by leaving my grip heaters on overnight

the engine's a pre-leader and it's not got an immobilizer so we can rule those out

same symptoms happened on my et. turns out i forgot to fully tighten the battery terminals. battery was not charging. after a few miles of riding, it won't start-up right away, had to kick start her. i related this to engine being hot = wont start.

8)

Terminals were tight - but good thinking, it could easily have been that!

I've had it confirmed by my mechanic and Doug that it's more than likely to do with the valves, something about them sticking or being tight, (not too sure what the right techy phrase is). She's booked in with the mechanic on Thursday for a carb clean and a look at the valves, so I'll know for sure then. Plus she needs the check up anyway.

Thanks for all the suggested problems and solutions

Tight valves are usually only a problem for cold starting - but if that proves to be the case on yours then great.

fuel filter?? plug wire cap??

plug and all relevant connections checked - all good. the plug looked about perfect as well.

the ET4 doesn't have a fuel filter that i'm aware of other than the one that's in the fuel tap - which i don't think has ever been checked.

Doubt it - once started it ran like a champ without faltering once.

on older scoots with coils that are on there way out they tended not to start when hot, left for awhile they would go but the ET has an elecronic ignition but could be that is on the way out or a loose connection or corroded at main fuse.

Could be electrical - but my bet is still on a fuelling issue. A valve check and carb clean won't hurt anyway.

Today I got the valves checked. The top one didn't need adjusting, but the clearance on the bottom one was over the recommended measurement. Also the carb got a good clean, a few of the jets were nearly blocked. Liz is now purring like a lioness who is close to being pissed off. She seems to be starting up a lot better too.

We did look at and test the auto-choke and it seems to be functioning fine, although it did get a bit warm, but it was said this was normal. So the true test will come when I go for a long ride and get her really hot, but I think she'll be fine (touch wood, fingers crossed)

I now know how to check valves and clean a carb, I'm really pleased

Excellent.