QuestionIm trying to get an old b12 runnin but im not having much luck. Its got the briggs 300421 engine and i cant find a repair manual for this engine. Ive got good compression, fuel, and spark but it wont even try to start. the best it will do is backfire through the exhaust. I made sure the valves werent hung or something funny there. Set the points at .020 and lost spark. as soon as i tighten up the gap i get spark again, but obviously out of time cause it backfires out the exhaust. Am i missig something or do i simply have bad points? condensor? weak coil? im very familiar with kohler engines but this briggs is messing with me. Thanks for your help!
AnswerBriggs timing is very simple as compared to some Kohler engines. I would set the points at .018.
Did you check the valve clearance gap? Is the flywheel key sheared?
The link below is the Briggs and Stratton Check Chart with valve clearances:
http://www.perr.com/pdf/ms3992_041008.pdf
The B12 is a really neat tractor...they definitely don't build them like they used to!
Parts link:
http://www5.briggsandstratton.com/eu/en/pdf/illustrated_parts_list/100/MS5611.pd...
I agree it is a timing issue but there is only two timing sources: 1) points/ignition/flywheel key and 2) mechanical, cam, valves
Check the flywheel key.
Eric
