Valve adjustment

[Mattmotors]

Hi All, I have a Sears Craftsman GT 3000. Model 917.275042 Serial 012402a00129
It has a Kohler Pro 23 HP CV675S Spec 75544.
Bought this new in 2001. It is hard to turn over till it gets past the first compression and back fires or explodes (which ever you would like to call it) thru the exhaust upon shutting it off. I have never adjusted the valves on this and I think it is time.
Can someone give me the correct measurements for the exhaust and intake valves.
I put ag tires on it and call it my brush hog. Still running strong for an old dog. Thanks , Matt.

 

[StarTech]

No adjustment. Hydraulic lifters. And no ACR on camshaft either.

 

[geelee]

this engine uses hydraulic lifters, no adjustment. also no compression release, my best guess is a weak battery or starter

 

[Mattmotors]

Thank You for the info.

 

[slydog]

Hi All, I have a Sears Craftsman GT 3000. Model 917.275042 Serial 012402a00129
It has a Kohler Pro 23 HP CV675S Spec 75544.
Bought this new in 2001. It is hard to turn over till it gets past the first compression and back fires or explodes (which ever you would like to call it) thru the exhaust upon shutting it off. I have never adjusted the valves on this and I think it is time.
Can someone give me the correct measurements for the exhaust and intake valves.
I put ag tires on it and call it my brush hog. Still running strong for an old dog. Thanks , Matt.

Try not lowering rpm's to idle B4 turning off key. Run about half throttle then turn off ignition. My Scag CH740 is the same way. Sometimes the simplest thing will resolve an issue. You're engine has hydraulic lifters and doesn't require adjustment. If you don't run at full throttle when mowing, you could have a buildup of carbon between top of piston and and head which will also cause pre ignition [ backfire when turning off key ]. These newer engines are designed to run full throttle when mowing.