LCGB Forums

I'm still alive, no longer in Europe and now living in very hot and sunny Southern California.

Air leak ?

Welcome back GP Kevo. Was wondering where on planet earth you are now wandering

Might as well tell us ya set up so the digital CSI can begin

Any number of factors will have caused that & I would have thought there would have been indicators prior to the catastrophe.

Sparkplug readings should have shown something that may have enabled a fix, but if, say, an engine is running very well, sounds 'fit', the tendency is to leave it alone. Truth is, there needs to be that extra safety margin. In this instance, I suspect jetting, which might easily be caused by altitude changes....

It'd be interesting if you add information to see the sparkplug, underside of the piston & the first internal part of the exhaust. As well as ignition, carburation, fuel, oil etc

If you achieved as good a seal between cylinder & exhaust as you did with head to barrel, I will be impressed Even more so if a head gasket was used....not that will ever get me to use one again in the conventional 'sandwich' context

Mostly I think it was two causes: not knowing what timing my friend had set for the ignition: 18 BTDC, and not raising the needle after riding at 6,000 ft elevation. Luckily I had a spare piston, and a spare reed block and gaskets etc so I spent the night before the USA Lambretta Jamboree rebuilding the top end. We trailered our scooters to the rally in Northern California, and my scooter ran really well. But I haven't had time to retard the timing to 17 BTDC which is where I've always run it since I learned how to set the timing. So no LA freeway use, for now. Those freeways suck anyhow, with cars regularly driving above 80 mph and a fair few well exceeding 100 mph, weaving in and out of slower moving traffic. I've even seen people street racing on the freeways, easily doubling what the fastest traffic was doing.

Since July I have had zero time to work in the garage as I've been working nearly non-stop to make up for a week long "vacation" without pay. I have barely caught up and I'm just about at the end of 21 consecutive days of work. On Sunday, when a lot of ye will be at the IOW, I'll hopefully have time to clean up my garage and reset the timing on my scooter and check the carb jetting which is currently 370 main, 58 jet needle on leanest setting, 25 pilot jet. If I raise the jet needle then the engine loads up / is over rich at 1/4 throttle. I'll go back to 22.5 pilot jet and see if that clears up.

Are you running an Amal carb Kev?

sounds like a Mikuni with those jets bud

Yeah possibly. Would normally expect that size of jet with a 57 needle. Yankee gas might change this tho?

Update: I ended up raising the jet needle by one groove and that's all I've had time to do. It's been reliable, though. The California gasoline is pretty poor quality. The highest octane available that is not racing gas is 91 Octane (about 95 RON). There are additives that aren't in European petrol. It is possible my carburettor is worn. I'm going to Sudco next week to buy a new TMX 35 and I'll try that with new jets and needles.

I'm doing a rideout the HIVE scooter club is hosting next weekend, and then a ride to Joshua Tree national park for camping on November 12, so I'll see how it does on a long ride.