Replaced head gaskets due to leaking oil and now the governor won't regulate the speed of the engine. All linkages to the propane carb are connected; however it does not move the arm which is connected to the governor to control the speed.

It sounds like you've already done a lot of troubleshooting, but here are a few more things to check:

1. Spark Plug: Check the spark plug for any visible damage or deposits, replace if needed. Make sure it is tightened properly and there is a strong spark when cranking the engine.
2. Fuel Filter: Check the fuel filter for any clogs or debris, replace if needed.
3. Air Filter: Check the air filter for any damage or clogs, replace if needed. A dirty air filter can restrict air flow to the engine and cause it to stall.
4. Vacuum Leaks: Check for any vacuum leaks in the fuel system, this can cause the engine to run poorly and stall.
5. Governor System: The governor system regulates the speed of the engine. If it's not functioning properly, the engine may stall. Check the governor arm, linkages, and springs for any damage or looseness.
6. Ignition System: Check the ignition system, including the ignition coil and ignition module, for any signs of damage or wear. Replace if necessary.
7. Fuel Pump: Check the fuel pump for proper operation, the fuel pump may be failing and not delivering enough fuel to the engine.

These are just a few possibilities, and it's best to consult the owner's manual or a professional mechanic to diagnose and repair the issue.

The maximum rpm is regulated by the governor - most small machines powered by petrol engines where high rpm would be a problem have a governor that usually fall into one of two types. Machines at the budget end of the market tend to use a movable vane inside the air cowling and as the engine speed is increased so is the air pressure against the vane increased causing the vane to move against it's return spring and in doing so tends to pull the throttle towards the closed position slowing the engine until the spring pressure is in equilibrium with the throttle pull spring.

Leaves, grass and other stuff can find a way into the air cowling and jam the air vane operation and is commonly the cause of overspeed as is general wear, incorrect assembly or maladjustment.

Engines at the more premium end of the market tend to use a centrifugal governor where the gubbins is inside the engine crankcase though the operating principle is similar - the throttle butterfly is pulled open by a spring connected to the hand control and the governor arm will move as the speed increases tending to pull the throttle closed until again and equilibrium exists between the two springs. This type of governor is reliable but the connections to the throttle are just as prone to wear, damage or maladjustment.

Sounds like your governor linkage and or governor control fan arm " most small engines have them to control over speed" is binding or maybe has dirt and grass built up.. Or the return spring is disconnected. Once it starts to race manually move the governor linkage back an let go see it it stops racing.. Then release if it races again..check the spring if connected...you must check the governor fan it is located under the top housing..it uses the engine fan calling air to slow the engine when over speed occurs by pushing the governor linkage back to slower speed.. Check it out...good luck..

It still sounds like a carburation issue. Are you sure all jets, vents and ports in carb are open? Another possibility is that the governor setting is off. The governor is the rod that comes out of side of engine and connects to throttle linkage on carb. To set governor to factory setting, push governor linkage in direction that opens throttle valve, loosen screw on governor arm and turn rod in same direction until it stops, while holding in this position tighten screw on governor arm. This is called a static setting. If this doesn't work I would disassemble carb, remove all plastic and rubber parts and soak in carb dip overnight. Picture may be different from your unit but it shows governor linkage to carb. Good luck and happy wrenching!

I’m happy to assist further over the phone at https://www.6ya.com/expert/layne_0fccff498c319c32

the cable hooks to a lever that is connected to the governor, the gov. is the shaft comes out of the side of the block, rather than the carb. in turn the governor has a linkage that goes back to the carb. to regulate the engine RPM.

First thing to check would be the base governor setting.This should be done by someone with small engine expertise.Can be fatal to engine and do bodily harm if not done right.Other things to check would be air leaks where carb manifold attaches to heads.Remove air cleaner assembly to gain access to carb linkage and manifold.You will need a can of carb cleaner to perform this check.Start engine and hold throttle at just above idle speed and carefully spray area where manifold attaches to head,do this on both ends of manfold and at carb base,area where carb mounts to manifold,if leak is present the engine will either die or their will be a change in rpm,s.If no leaks are found in these areas have carb cleaned,it is very likely there is dirt in the carb.You can do the same as above,start engine and hold throttle just above idle and spray carb cleaner into carb,engine will try to stall when doing this,only spray carb cleaner in carb while engine is running.If this doesn't help have carb cleaned and adjusted.Info from small engine tech with forty plus years experience.

This problem may SEEM carb related, but it is probably a result of bad linkage to the governor (controls engine speed) and may mean the governor needs adjusting (easy) or the linkage to the governor is stretched or not connected properly.

sounds like air leaking into the intake.replace the gasket that is in between the carb and the block

Make sure that the throttle linkage is all there and not damaged/misadjusted, then get a manometer and check your inlet gas pressure. Gas pressure should be 8 inches of water column and stay there running or not.

Carl

I've never been a big fan of the 180 OH family of engines in these things, but here goes.
1 - If the engine will stay running while it surges, close the choke a little at a time and see if it settles down. If it does, there is something amiss in the carb. The carbs on these engines are very picky about tiny bits of dirt. The good news is that they are fairly simple to take apart and clean, the bad news is that lots of the parts are plastic and break easily. At least they aren't too expensive.

2 - I've seen 2 ways to adjust the governed speed on these engines; a spring that connects to the governor arm at one end and a tab bent up from the sheet metal that mounts on top of the engine at the other - bend the tab so the spring is tighter to speed the engine up, and (b) a jam nut and screw mechanism that presses against a lever that pulls on a spring that connects to the governor arm - screw the screw in tighter to raise the engine speed.
Note that in either case the mechanism adjusts the tension in a spring that pulls against the governor arm, this is helpful in finding out where to make the adjustment.
Here in the US we want our 2 pole generators like this to run at 3750 rpm at no load so that we get very close to 3600 rpm at load. If you're using a DMM to measure the output of the generator in Hz, you want 61.5 at no load.

If nothing you can do with the choke makes the surge go away, you might have a misadjusted governor. The Tecumseh service manual has a great procedure for making this adjustment, essentially what you do is loosen the retaining nut on the governor arm, twist the governor shaft to its minimum speed position, then hold the throttle assembly at the idle stop and tighten the governor arm jam nut. Always keep a finger near the kill switch when running the engine the first time after this procedure, it's easy to mess up and have a runaway engine.

Please rank me if this was helpful,
Carl