Briggs and Stratton 6hp will not start when hot?

[limoman39]

I have a Briggs verical shaft 6hp intec OHV Motor that will not start when hot. The motor runs great until I need to shut it off to refuel or move something. I have to wait about 2 hours for it to completely cool before it will start again. I have already replaced the Magnetron (gap set with bus. card), spark plug, checked the valve lash. What am I missing? This thing is about to drive me completely crazy!! The valve lash is on the top of the recommended scale, I believe it is .004 to .006. I thought maybe when it got hot the valve might be sticking open. I do not notice a difference in pull starting cold or hot. Can anyone give me some clues based on experience.

Thank you,

 

[mechanic mark]

Post your model, type, & trim numbers, xxxxxx, xxxx, xx. Check air filter for replacement, also engine oil. Remove spark plug boot then top cover of engine & clean everything carefully by hand, no water or liquids, with an old toothbrush or nylon bristle brush removing all dirt & debris, you can use a shop vac after loosening everything up. Engine needs to breathe & run cooler after performing the above. Also cut fuel off and clean under deck, check blades for dressing up with file then balancing, first clean blades & inspect them for cracks etc. or for replacement. Let us know how it goes, thanks. Whenever you turn mower on its side be sure carburetor side is up.

 

[pugaltitude]

Spark plug should be set to 20 thou for this reason.

Usually a champion RC12YC would be fitted but you could try a RC14YC.

Also check spacer between carb and engine.
They can warp and cause a bad start issue.

Another thing which can be unsual but briggs went through a batch of flywheels losing their magnatism which caused a bad hot start but that was years ago.

 

[pugaltitude]

Another one is is the blade fitted to locating pins or does it use a friction washer?

If it uses friction washer then you could turn your engine to TDC and then slack blade bolt and turn blade to line up with piston .