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. I have rebuilt the carburetor and replaced most of it. That has helped slightly as it only used to run for about 5 minutes before. I have also replaced the head gasket. The are under the head was rather black but I have cleaned this off. The inlet valve was a funny pink/coral colour. What can I do to make it run longer? Why does it keep stopping?

Thanks