Fråga: Hello. I have a Monark M77 with a JB 150cc engine from 1952. Its in original patina condition, starts after a few kicks and runs well while riding.
However, when I leave the bike to idle it just shuts off after a few seconds. In basic terms, it just won’t idle. Do you know why this may be? I am new to motorbikes and trying to learn with this one.
Many thanks
Douglas
Svar: There could be many reasons for this. Wrong abriss (wrong contact breaker gap) can give a weak spark at low revolutions like idling. Maybe there is a low fuel level in the carburator.
The contact breaker gap on a JB 150 should be 0,35 – 0,45 mm and then the abriss gap should be 7 – 10 mm at the same time. If not – the contact breakers are probaly worn and should be replaced.
Jim Lundberg
