LCGB Forums

I have a 1957 Ser3 150cc Ld. Recently replaced plug, points and condensor. Also had the tank professionly cleaned and resealed. Engine starts, runs and ticks over fine. After about 20 minutes riding under steady throttle, the engine just dies. Leave it for 10 minutes and it will start and drive for a while then cut out again. Almost sounds like overheating. Any suggestions please. (legal ,achievable only please!).

When it dies check the plug, is it wet ? if dry could be fuel issue.

With plug out have you got a spark ? no spark/electrical.

Obviously not going to be as simple as that but the plug may give an indication of whether it's fuel or electrical.

Checked the petrol cap breather hole?

Breather hole? That reminds me - almost all LDs have the usual breather hole in the filler cap, but some of the late Mk3s have a separate metal vent tube that runs down inside the tank and exits underneath. Those have a filler cap with no vent hole - just make sure your tank is the type with the separate breather if you have no vent hole in the filler cap!

If that's not the problem, it might be worth checking the HT coil, these can give an intermittent fault when they get hot, but seem to work OK once they've cooled down. Similar problem can occur with the condenser - just because it's new doesn't mean it's not faulty!

Thank you all. Lots of backing for some of my own theories. Busy weekend me thinks.

Classic sign of a failing condenser as well.

Hi pg42, did you sort it out as I've posted a very similar problem?