Mustang 310 Poor performance

[Gatorsfan]

I recently purchased a 1979 Owatonna Mustang 310 w/ a 14 HP Kohler 321-S motor. The 2nd owner bored engine out .030 prior to 2006. The 3rd owner replaced the ignition coil, breaker, condenser & Hi-Tension kit (Whatever that is??) in 2007. The filters & hydraulic fluid were changed in 2015 w/ new hoses. (I'm the 4th). I put a new carburetor & spark plug on it within the past week. Symptoms: The compression at the cylinder is 90 PSI (Should have checked that prior to spending $'s on it). Machine will start (a little hard) & run fine. I do 10 minutes or so of work with it & it conks out. Restarting is very hard if at all w/ bucket relieved of all pressure & drive clutch disengaged or until motor has cooled down (70 degrees was the minimum temperature outside). Is it time for a new motor? My thinking is motor should have at least 100 PSI minimum to keep this running. If this is the case I would like to upgrade my power. (19 HP minimum) Do I need to find a specific shaft size? Is it horizontal or vertical that I need? Any recommendations are welcome. Thank you.

 

[Hotrod1830]

Does the motor have good power until it gets hot? Keep in mind 14hp isnt alot to begin with.
90psi of cranking pressure isnt bad. If the spark plug looks good and isnt oil fouled, it is probably OK.
When the engine dies and wont start, start checking the basics. Squirt a little gas or carb cleaner down the carb(reinstall the air cleaner before) and try to start it. If it starts and dies, you have a fuel delivery problem. If it does not, check for good spark. (p) Dont forget, just because parts where replaced, doesnt mean they cant be bad again, or installed incorrectly. Check point gap, and check for burned contacts. Ohm the ignition coil cold and hot.
Aslo dont forget to check valve clearance. rarely is that ever checked.

 

[Gatorsfan]

Does the motor have good power until it gets hot? Keep in mind 14hp isnt alot to begin with.
90psi of cranking pressure isnt bad. If the spark plug looks good and isnt oil fouled, it is probably OK.
When the engine dies and wont start, start checking the basics. Squirt a little gas or carb cleaner down the carb(reinstall the air cleaner before) and try to start it. If it starts and dies, you have a fuel delivery problem. If it does not, check for good spark. (p) Dont forget, just because parts where replaced, doesnt mean they cant be bad again, or installed incorrectly. Check point gap, and check for burned contacts. Ohm the ignition coil cold and hot.
Aslo dont forget to check valve clearance. rarely is that ever checked.

When you are talking "Valve Clarence" what kind of tool do I need> I have a basic measurement tool for inside & a better for outside. when it comes to thousandth's probably not going to get an an accurate account & really a rebuilt engine bored out .030 is not worth rebuilding again. valves or otherwise. Not to be combative...just realistic.

 

[SkidRoe]

When you are talking "Valve Clarence" what kind of tool do I need> I have a basic measurement tool for inside & a better for outside. when it comes to thousandth's probably not going to get an an accurate account & really a rebuilt engine bored out .030 is not worth rebuilding again. valves or otherwise. Not to be combative...just realistic.

You need a set of feeler gauges to check the valve clearance. There is a cover on the side of the block that you will have to remove to access the valve springs. It is likely behind the carburetor. The clearances should be checked cold.
The intake valve clearance should be 0.008-0.010" and exhaust should be 0.017-0.019".
Adjusting the clearance typically involves removing the valve and grinding material off of the end of the stem.
As far as repowering goes, here is a resource that could give you some ideas/advice:
http://www.smallenginewarehouse.com/
HTH - SR

 

[Tazza]

You need a set of feeler gauges to check the valve clearance. There is a cover on the side of the block that you will have to remove to access the valve springs. It is likely behind the carburetor. The clearances should be checked cold.
The intake valve clearance should be 0.008-0.010" and exhaust should be 0.017-0.019".
Adjusting the clearance typically involves removing the valve and grinding material off of the end of the stem.
As far as repowering goes, here is a resource that could give you some ideas/advice:
http://www.smallenginewarehouse.com/
HTH - SR

Good advise to try some fuel in the carb to see if it kicks.
That compression seems ok to me too.
I also believe it's not a wear issue, for it to just die, it has to be loss of spark or fuel. If it was worn, it would be hard to start and potentially blow smoke.
The ignition module is one thing that can stop working when the motor gets hot.

 

[Hotrod1830]

Good advise to try some fuel in the carb to see if it kicks.
That compression seems ok to me too.
I also believe it's not a wear issue, for it to just die, it has to be loss of spark or fuel. If it was worn, it would be hard to start and potentially blow smoke.
The ignition module is one thing that can stop working when the motor gets hot.

On my old Kohler K341, the valve tappet had an adjuster on it, you just used a wrench to adjust valve clearance. The K321S is the same engine family if I am reading correctly.
Diagnose the stalling first. More than likely it is a loss of fuel or spark. In a extreme case, valve clearance can do that, but they usually get loose with use, not tighter. Unless someone got them too tight when trying to adjust them.
If you checked compression when it stalls/ wouldnt start, valve clearance is not the root cause.