Lambrettas everywhere

A Friday off work and it's a beautiful September day, so it was high time I took the scoot for a fast run up the Long Ashton bypass to check that everything is working as it should be. I had to fill her up with fuel first and here's where I made a mistake. I expected to be putting in 6 litres of fuel so I dropped in 250ml of oil prior to filling. Unfortunately the tank was full after 5 litres, so I'd miscalculated, and now had an incorrect fuel/oil mix of nearly 5%. I figured this shouldn't matter too much so carried on with my ride.

I sped along the bypass and it ran really well, keeping up with the traffic probably at around 55 or 60mph, although with my kph speedo and non-standard tyres it's difficult to tell.

But then, pulling off at the first junction the engine died while coasting, so I bailed out to the central reservation and started poking around. Compression was ok, and everything sounded ok, but it wouldn't start. The only tools I'd bought with me were some pliers, crimpers, meter and screwdriver - I was planning only to tweak the erratic rear light!

I'd been there 3 mins max when out of the blue a chap called Geoff pulled up on his S3 to lend a hand.

He had a spark plug spanner, so we removed the plug, gave it a wipe, cranked the engine a few times with no plug, and then refitted it. Geoff had the honour of trying to restart it - and start it did, with Geoff's 'full throttle' technique. Although I did have to increase the idle speed to keep it going, and my theory is that my problems were down to the fuel mix. Thanks to Geoff who turned up at just the right time!

Geoff went on his way and just as I was about leave, another Lambretta rider turns up. This time it's a chap called Ian:

It turns out he lives just down the road from Geoff, but they don't know each other. Ian was tentatively running in his GP and had only a few weeks ago suffered a seizure on this same stretch of road.

So if you want to meet other Lambretta riders, break down on the Long Ashton bypass on a sunny Friday morning. From now on I'll be carrying 200ml of oil for a 4.8 litre fill-up, giving me my target 4% ratio.

Jetex carb air mixture screw

The setting for the Jetex air mixture screw is different to that of a Dell'orto, so don't blindly follow advice for the wrong carb. For a Dellorto SH carb we are told to start off about 1 ½ turns and go from there. For a Jetex however, there's a label on the side that clearly states we shouldn't be going more than ¾ turns out.

To set the mixture properly, first warm up your engine. Then set the throttle idle screw (no. 26 in the diagram above) so that it holds the throttle open with the engine slightly fast. Now we need to set the mixture screw (no. 13) so that the engine is smooth and regular. Turning the screw in will make the mixture leaner, and out will richen it. When you have the smoothest tickover try opening the throttle. If the engine splutters or stops then a little more adjustment, probably to make it richer, is needed to eliminate this.

You'll probably end up somewhere between ½ and ¾ turns out.