B&S 12hp Trying to Break My Arm

[RoysAtco]

Hi to everybody.
I'm new here and I wonder if anyone can help with this problem, please?
My 1990 Atco ride on (Briggs&stratton 12hp 281707 side valve) was given to me as a non starter. The ignition module was faulty and replaced. So far so good. It was starting but when I activate the cutter deck it would stall. This was because the revs were not high enough on max. Main jet on carb was badly scored and the throttle plate had a ton of play so the carb was replaced with a new one. This was after I noticed that on every compression stroke fuel and air was being pushed out of the carb. The engine inlet valve was not closing properly at a quarter inch passed tdc. Unfortunately I took too much off the valve stem and the minimum gap I've got is 15 thou. Both valves lapped in, by the way.
Due to what I think is pre ignition the damn thing now backfires very loudly and snatches back the rope big style; I'm using the rope now because the starter plastic cog has stripped because of the problem.
So, I was confident that the flywheel key had broken, but it's in perfect shape.
I now haven't got a clue what to do. I don't want to give up but I'm getting close.

Thanks in anticipation

Roy

 

[Romore]

'Unfortunately I took too much off the valve stem and the minimum gap I've got is 15 thou.'
There is your problem. The compression release is not working, replace the valve.

 

[bertsmobile1]

Or fit a lash cap or cut .010" off the seat.

 

[RoysAtco]

Many thanks guys for your help. I think a new inlet valve is the way to go for me. That'll teach me to be too heavy handed with the file. That's a mistake that won't happen again.

 

[bertsmobile1]

Generally you use an oil stone to avoid this happening