Briggs 3.5 hp Hard Starting

#1
Well I finally got the carb cleaned and the motor running, but the only problem I have is once the motor is hot it is very hard to start. My question is should I lap the valves or put in new rings? I got this motor used and have not taken the head off or anything.
 
#6
If it starts fine cold it has plenty of compression to be a runner. Valves will tend to loose their seal when hot as things expand and move during the heating cycle. The engine will run as long as you keep it going. Then when you shut it off they can be a bugger to restart, until they cool. Also verify the exhaust valve guide is not overly loose, old engines have issues with that too. Pop out the valves and look at the face of the exhaust valve. If it is all black on the sealing area it is leaking. At minimum lap the valve (cutting the seat and face is far better) and then set the valve lash. If you work fast it takes less than an hour to do this job.
 

Doc1976

Active Member
#8
a leak down test will tell you need to know without taking anything apart. if you have a motor with the compression release lobe on the cam, you wont get an accurate compression test result.
 
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