Gx345 high idle

[Heinlein0311]

Just got my gx345 with the 20hp liquid cooled kawi out of the shop. They replaced a lot of parts including the governor. The tractor idles higher than normal no matter where the throttle is at, but once the pto is engaged it's a little better. Is it the governor or the carb that needs to be adjusted? And how do I go about doing it? Also, once I've been using the mower for a while I idle it down for a minute before shutting it off, buy then it gives off a big backfire. Anyone know what causes that?

 

[beenthere]

How about a list of what things the shop did? Help to know the history that led up to your problem(s).

I didn't quite follow the "tractor idles higher than normal no matter where the throttle is at" statement. Are you saying the throttle has no effect on engine rpm speed? or ??

Does it also backfire if just turning the ignition off without "idle down for a minute before shutting off" ??

 

[Heinlein0311]

I bought it from a Deere mechanic. It started smoking like a freight train. So he took it and replaced the crankcase cover, new rings, gaskets, 1 new rod and piston, governor....there may have been more but that's what I remember. It was kind of a weird situation on who should pay for what but we worked it out.

I meant it idles higher than what it should wether the throttle is all the way down or up. There is a difference in rpm when the throttle is moved, although it's the same rpm from the low throttle to half throttle position.

I have not tried just shutting the machine down without idling it down first. I was taught it was bad on the valves and rings and with it having new rings and valves I didn't want to screw it up.

 

[Eric Barney]

The governor's job is to maintain a set RPM at full throttle only. It will still have an effect at other throttle settings, but not so much at idle. The idle speed is set with a stop screw on the carburetor. When the throttle lever is set to idle, the governor lever should be forcing the butterfly (On the carb) to the closed position. A screw stops the butterfly valve from closing too far, and causing a stall. This screw sets the idle speed.

The throttle lever on the tractor controls should be able to adjust the engine speed anywhere between idle and the full throttle governor limits. If it does not, it is not set up properly.

 

[beenthere]

A good explanation Eric.

 

[Heinlein0311]

So by adjusting the idle screw on the carb, it will help the tractor idle better in the idle position but not at full throttle?

 

[beenthere]

The following from the manual. What are you following for a guide to which screws are available to adjust? A pic of the carb and parts exposed may help give you some thoughts to help you.

NOTE: Carburetor is calibrated by the engine manufacturer and is not adjustable.

If engine is operated at altitudes above 1829 m (6,000 ft), some carburetors may require a special high altitude main jet. See your authorized dealer.

If engine is hard to start or runs rough, check the TROUBLESHOOTING section of this manual.

Possible engine surging will occur at high throttle with transmission in "N" neutral and mower engagement lever disengaged. This is a normal condition due to the emission control system.

After performing the checks in the troubleshooting section and your engine is still not performing correctly, contact your authorized dealer.

 

[Eric Barney]

So by adjusting the idle screw on the carb, it will help the tractor idle better in the idle position but not at full throttle?

The idle screw setting has nothing to do with full throttle. So I understand your questions better, here is how I view throttle positions:

Idle: The slowest RPM the engine will run. The throttle is all the way down, and the engine is running at a slow speed. Loads of any kind are rarely imposed on the engine while it is idling. Like when you are off the tractor, and do not want to shut it down. Generally, the PTO is off, and the tractor is in park/neutral while idling.

Full Throttle: In most cases this is the working throttle position. The governor keeps the engine speed constant no matter how much load is imposed. Unless the work load excedes the rated horsepower of the engine, the engine should always stay at the RPM set by the governor. Always cut grass at the full throttle position.

Part throttle: Any setting between "Idle" or "Full" The engine runs at a slower speed than full, but produces enough power for slow driving, or maybe pulling a tow behind attachment. Part throttle is also good for faster warmup on the water cooled engines.

A sure sign of a properly tuned engine is when it runs smooth at any throttle position, maintains a constant RPM, And has a nice smooth idle! When carburetor issues are present, (Such as plugged idle jets.) the engine will surge up and down constantly. It may surge less under load because of the governor opening the carburetor throttle to compensate.

An engine that is idling too fast is an indication that if it were set to idle nice and slow, it would stall or surge badly. Or the throttle control is not properly set up.

 

[Heinlein0311]

Your last paragraph is what has been my concern. You would think any good mechanic would realize that it was idling higher than normal. Im thinking the same as you and that if it was tuned down a little it would stall....

Now I'll try to put my symptoms into how you worded it: First, the engine does not surge at any throttle setting. Constant rpm is maintained. It's that the rpm is higher than what it use to be.....there is not much rpm difference between idle and half throttle, after that it's a noticeable increase

 

[Eric Barney]

Sounds like the governor setting has been changed to a higher RPM.

That certainly could effect all throttle settings. (including idle speed) If it has been set to a higher speed, that will have a negative effect on engine life and fuel consumption. Restoring the proper setting should be a high priority.

Hopefully, the tech did not raise the RPM's to cover another problem. You will need a tech manual for the proper governor setup. Since there is no surging, adjusting the governor should be all it needs.