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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 18559
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have Toro LX500 Tractor with a Kohler Courage SV720 Engine.

Customer Question

I have Toro LX500 Tractor with a Kohler Courage SV720 Engine. It is very hard to start - the engine has too much compression at the start so the starter can't turn it. If you assist by turning the engine by hand while turning the key it will start. We adjusted the valves to .006 and tried a new starter but neither worked.
Any suggestions?
Submitted: 2 years ago.
Category: Small Engine
Expert:  James W replied 2 years ago.

James W :

Greetings, My name isXXXXX and I am here to help the best I can. My goal is 100% satisfaction. Let's get started.

James W :

I believe I do know what you problem is and how to fix it


Your engine is equipped with a compression release


This is because it is a High compression engine


The compression release is not activating


This is why it will not turn past the compression stroke, but spins fine with no plug in it


This would indicate that the valves are out of adjustment


If the gap is too wide, then the compression release is never activated because the valve never is lifted partially up at lower RPMs like is should allowing some compression to bleed off..


 


Most likely the problem is that the valves need to be re-adjusted. There should be between .004" and .005" clearance between the valve stems and the rocker arms when the valves are completely closed. If this is not correct, then the compression release will not work and the engine will be hard to turn over.


 


Also make sure that you have the proper amount of oil in the engine.

James W :

you are so close to solving the problem

James W :

but you need to reset the valves again

James W :

Set the valves with the spark plug out

James W :

and keep rocking the engine back and forth or tunring it

James W :

until you are 100% sure that you are setting each valve at its absolute widest opening or gap

James W :

I will locating a service manual which will help you

Customer:

Are you sure there is compression release on this engine? Other technicians have told us that there is NOT a compression release on this model engine.

James W :

99.9 % sure but I will double check

James W :

Usually the instructions are in chapter 9 or 10

James W :

And here also is the newest version of the owners manual

James W :

You should adjust the valves every 12 to 18 months

Customer:

Wow - thanks! Will check this out and let you know what happens!

James W :

page 19

James W :

of the manual reads

James W :

These engines are equipped with an automatic compression release (ACR) mechanism. It is difficult to obtain an
accurate compression reading because of ACR mechanism. As an alternative, use cylinder leakdown test described
below.

James W :

I guess that settles that...as in the discusison with the other techs

James W :

also the valves shoul dbe set at .004 and .006

James W :

let me know if you need more help

Expert:  James W replied 2 years ago.
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Customer: replied 2 years ago.
Good Morning! We adjusted the valves correctly and still the engine would not start, or would start very hard. We ordered a camshaft and diaseembled the engine. The camshaft does not have a compression release valve. What should we try now?
Customer: replied 2 years ago.
Relist: Incomplete answer.
We have a Kohler Courage SV720-0011 engine. Very hard starting, seems to come up against compression. Was told by other technicians this engine does not have a compression release, we need to adjust the valves - which we did. Still did not work, got onto this website, James W said to adjust the valves - we checked them again - still did not work. James said there was a compression release on the camshaft, so we ordered a camshaft and disassembled the engine, only to find there is not a compression release on the camshaft. Now what do we do?
Customer: replied 2 years ago.
Relist: Inaccurate answer.
Expert:  Curtis B. replied 2 years ago.
Welcome to JUST ANSWER small engines, let me try to help you !! Will the engine spin if you just pull the plug wires off? If it does, the spark advance is firing too soon before piston is at tdc.?? Does this engine have Smart Spark on it??
Customer: replied 2 years ago.
No. It is a compression problem. Once it reaches the compression stroke the engine stops turning on either cylinder. It is not an ignition problem. The engine will not turn if you just remove the wires. If you remove the plugs it will turn.
Customer: replied 2 years ago.
Relist: Other.
Kohler Courage SV-720-0011 Engine - hard starting, comes up against compression
Expert:  Curtis B. replied 2 years ago.
What are the voltage reading on the battery before start and while in the start position? Battery should have 12.5 or more and not drop below 8 volts in the cranking position. If it drops below 8 volts, the battery is dead or bad.??
Customer: replied 2 years ago.
Voltage is fine - 12.5 and around 10 at the cranking position. What else can we try?
Expert:  Curtis B. replied 2 years ago.
Voltage sure isn't dropping when starter is engaged. Check the starting voltage at the starter. You could have a bad cable, not letting full voltage get to the starter.?? With engine hard to turn, starter should pull voltage down more than 10 volts.??
Customer: replied 2 years ago.
We will check it again - but even if we jump start it, it comes up against the compression and is hard to turn over.
Expert:  Curtis B. replied 2 years ago.
Unless you are jumping at the starter, the cables are the same.

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