"Steve Sampson" wrote in message
...

Hi,

I have a Mountfield M1 rotorvator with a Briggs and Stratton engine,
model 111902. The problem is it runns for 10-15 minutes and the conks
out. It will then not start for about 10 minutes.

First check fuel is getting to the carb. Does the fuel run freely from the
supply pipe, if its an under carb tank is the diaphragm/gasket between carb
and tank in good nick/fitted correctly. Check the choke is it clearing the
carb opening okay. check the air filter, try running the engine without an
air filter. The filter or choke may be restricting air flow which the engine
won't mind whilst its cold but will object to once hot. If this is all ok
look to the main jet in the carb is it getting blocked by crap from a rusty
tank.

Then check the spark. Are you getting a spark when its hot? This may be
caused by a dodgy HT lead/cap. If the engine has points ignition have you
replaced them and the condenser. Both located inside the flywheel and can be
a bugger to get to. Have you dead stalled the engine by hitting something
solid? More common with direct drive rotary mowers I know but a bad stall
can slightly shear the woodruff key keeping the flywheel in position thus
altering the timing. Again a cold engine may not mind the timing being a bit
out but a hot one will.

If fuel and spark are okay, then the problem may be that the engine is
simply worn out, in which case Charlie had the best advise.

Mike
www.farend.org.uk