Small Engines (Lawn Mowers, etc.): valve adjustment, briggs and stratton, compression stroke

Question
I have a briggs engine on my Troy-bilt rider that is very hard start. I know it has too much compression so i adjusted the valves, but it made no difference. The model number on the engine is 31P777 and the type is 0293E2.  I set the intake to .004" and the exhaust to .006" with the piston 6mm past TDC.
Your help would be greatly appreciated.

Answer
Hi Barry

here is  parts web site  to help  

http://www.partstree.com/parts/?lc=briggs_and_stratton&mn=31P777-0293-E2&dn=5766

are you sure you dont have   oil  or fuel getting in   and reducing clearance volume   which increases  compression ?

being OHV single  , did you set cylinder to tdc compression stroke then run the piston down the bore on the power stroke by 1/4 inch ( 6.35mm)   then set valve clearances to 0.004 inlet  and 0.005 Exhaust   inlet is the bottom push rod and will,be  alloy  and the top push rod exhaust and  is steel

with the plug out   physically rotate the cylinder by hand  and watch the inlet valve  open and close the valve a litle as it gets very close to tdc compression stroke  
if it does not open the valve approriatly or at the right time  , it may have a camshaft decompressor problem

with plug out and the roker cover off  use stater motor and crank motor over  watch inlet valve  does it actiavte decompressor - you will see it  open and close the valve a little

does the starter turn the motor over  then seems to hang up  as if really labouring  near tdc and not get to go past tdc - starter motor gets hot  - high amp draw  

is your battery and starter motor in good condition  along  with solenoid   and wiring
if resistance  and excessive volt drops in the circuit are there  starting will be affected

check these out 1st  before  going to confirm camshaft / decompressor problem

but have seen same symptoms before


hope this helps

let me know  what you find  


cheers paul