Best way to turn off lambretta...??

[S2CUF]

Hey. So I'm new to all this lambretta malarkey... What's the best way to turn off my lambretta, bloody thing doesn't seem to want to start... It's a li150 kitted to a 175. And a 22mm carb.. Once it's started it runs fine.. But when I turn it off. It doesn't seem to want to start again, I have to take the plug out, which is wet, dry it off, kick over the engine with no plug, then put back in and sometimes I have to keep doing this, I have always got a good spark, but struggle to get her to fire up. I was told to turn the fuel tap off, and let it run out of fuel and die off naturally.. Please be gentle as I know apsolutely nothing about these....

[rosscla]

First change the plug for a new one and ensure the gap is set correctly. This could lead to poor or incomplete combustion.

It's more likely it could be flooding, too much fuel getting into the cylinder.

Sometimes this can be caused by needle on the float being worn or the incorrect one. Also check, if it's a Jetex carb, that the pin and float in the carb bowl move freely. It's also, with Jetex, worth seeing if the jets themselves are genuine Dellorto parts. Are they marked at all?

Does it have a standard air box / filter arrangement?

[S2CUF]

Yes standard air box etc.. What would be the correct spark plug?. And what should the gap be? What do you mean by that? Educate me please.......

[coaster]

It is worth checking all Ross's suggestions but the problem you describe is extremely common on non standard setups when warm starting and can be caused by the port timing on the 'tuned' cylinder. What happens is that mixture gets blown back out of the carb and it collects in a piddle in the air hose. When you go to re-start after a short break the puddle gets sucked into the engine and floods it. The work around for this situation is to always remember to turn your fuel off several seconds before you kill the engine and leave it turned off when you re-start it. You must always remember to keep the throttle shut when starting as well, wringing it will make it very difficult to start. Paying attention to Ross's list and some fine tuning of oyur jetting and idle screw can reduce or even eliminate the above problem if you are lucky.

Colin

[S2CUF]

That's exactly what's happening. I'm getting fuel gather in my air hose... So how can I resolve this? Does my carb need setting up??

[mick1]

a small drain hole in the bottom of the rubber usually cures this.

another possibility is that the choke isn't fully switching off. probably worth taking it all apart (the carb'), check the size of jets (make a note), give it all a good clean, and see how it goes.

[coaster]

As I said, do all the things suggested by Ross and Mick's too, if you are lucky that might make it better but don't be surprised if the problem persists. I had this problem with a Mugello 186 kit and never did manage to cure it. It would start with 0n3 or two kicks when cold but if it had only been switched off for a few minutes it would either not start of fire and just chug. I found the only answer was as I said above, turn off petrol shortly before stopping. That is what to do if it starts the chugging thing, turn petrol off and hold throttle open until it clears then turn petrol back on. It's a work around solution but plenty of us have to use it. The other alternative is to run a carb without the rubber elbow.

[Chris in Margate]

All of the above.
The thing I notice when we have a large turnout on a ride is that there is always one that doesn't start. I have watched knowingly !
Couple of kicks and the scooter doesn't start and then panic sets on and the old throttle starts getting wrenched wide open and loads more kicks.
And then we've all smelt it...The inevitable smell of petrol. It's flooded.
Keep that throttle closed !

[Chris in Margate]

PS: I've never had that problem on a 150/175 conversion before. I know the Mugellos can be bad for this but an unturned 175 should perform as Innocenti intended. Change the float needle.
Incidentally I can leave my fuel on for weeks and it always starts without problem. As said turning the fuel off before stopping is a work around to mask another problem.

[EddieStone]

If you're not mechanically minded, I'd leave it alone and find a mechanic to find the fault, if there is one.

To start it from cold: Open the fuel tap, open the choke and kick the starter. It should start after 2 to 4 kicks. Once it's running, close the choke. You only need the choke to start a two stroke engine. Close the choke as soon as you can.

To stop it, let the thing slow down to an idle and turn it off. Don't rev it then turn it off. I've no idea why people do that. Turn the fuel tap off.

To start it when warm/hot: Turn the fuel tap back on. Make sure the choke is closed. Kick the starter with the throttle closed. This is harder than it sounds if you are used to a motorbike. Once it fires, then you can rev it.

If this routine doesn't work, then there's something wrong with it. Could be over jetted or the carb set up incorrectly. Or it could even be the timing. Either way, if you've not worked on a scooter before, then this is not the place to start. Find a mechanic or someone in the area that's willing to help. Let them ride it for a bit and see if they have problems starting it. You could check the spark plug is the right type for the riding you do.