When I prime my mount field lawn mower which has a rs100 motor, I press the prime button a couple of times, the lawn mower starts briefly then cuts out. This happens every time. I have replaced the air filter, and the gasket seals.
Someone mentioned the diaphragm might need replacing but I'm not sure where this is?
It is a mount field hp414.

Andy w 4303, April 2015

The person who suggested a DIAPHRAM is a bar room KNOW ALL-KNOW NOTHING MORON !...... only the Briggs & Stratton engines have those......the RS 100 engine is a chinese lump with a FLOAT type carb....NEVER FITTED WITH A DIAPHRAM !
Remove carb bowl ( nut underneath ) & insert a fine fuse wire in the exposed jet. Also check if the type of carb has a jet access screw in the top ( some varients of this carb do ), if so, remove screw & clean top jet also. The top jet is best cleaned by blowing with high pressure air.

Gyno genius, April 2015

new spark plug/ empty the tank. put new fule in, make sure the fule is turned on,, try to start it with the air filter off, till you get it it running for a wile, if there is a choke on it turn it off after it kicks and make sure its off when running, its very easy to flood it when trying to start it , if things are not right, and is you do flood it, keep pulling the cord with the mower off, to dry out out the spark plug, then turn it on and try it again,

h, April 2015