Does the new carb have an adjustable main jet on the bottom? If so, is it 1 1/2 turns out from seated? Is the carb brand new from a factory?

Yes it dose have a main jet on the bottom. I got that 1 1/2 out. I try to ajust that too. Its a H30 tecumseh. 3 hp. Like i said,,,, it idles great,,,and ribbs up good,,,,But when u engage the tillers it dies. Very strange. It might till 3 feet then the engine bogs down and cut off. The gear box is full of oil. Yes the carburetor is new.

Does the drive belt get hot as you try to work the tiller or any other indications it may be a tiller issue? Is the governor holding the throttle shaft ccw as this is happening or do you notice that you can help the speed out by moving the shaft?

No the belt dont get hot.The thottle moves good. I adjust the governor and spring and it still do the same thing. I was thinking if the cylinder is wore. It idles good and ribbs up good without hearing any miss in it. But when i begin to till with it,,,,,,,it cuts off like it ran out of gas. I even check the coil to see if it was getting spark,,,,,after it cuts off,,,,,,,and its still getting spark. I even lose the gas top and try it,,,,,and it still cut off. It cranks up every time. I dont understand,,,Thanks

Try turning the screw out 1/4 turn more and see if it makes any difference.

Is the fuel line obstructed?

I have did that too. Still no luck. I got a new tygon fuel line on it. Already try 2 new plugs in it too. Thanks

Tiller engines don't have an easy life. Sounds like it's time for a Predator engine...

Maybe you are trying to do too much ground at one time. It doesn't appear to be a carb issue at this point. Did you mess with the governor? Is it running at 3000 rpm?

Yes i ajust the governor aleast 3 times. It dosnet take much to just a adjust the governor, just a little bit. I would say the rpm is around 3200 to 3400. I also put a new head gasket on it too. Thanks

While this is a long shot you seem to have tried everything else but When u lapped the valves, did u gap them ? its like .03 for intake .05 for exhaust. Anyone please correct me...

Also, if it is old enough, maybe the points are opening too late/early?!?!?

It dose not have points. I think this tiller 21 years old. Yes i gap the valves. 04 for intake,,,06 exhust.,, I just cant figure it out,,,,,It a H30 3hp tuffy troy built . With a tecumseh engine on it,,,,Thanks,,,,greg

IMO you going to figure why the compression is so low. IMO should be around 100 at least. At 60 PSI (it you sure that's it? or it has compression release) IMO about enough to keep it running but not enough to power anything.

Looks like you going to have to measure the bore, measure the piston, see if clearances are within limits. I would also measure ring gap in the bore, and ring side clearance on the piston. Other than leak down test to try and figure out where it leaking (intake out the carb. Exhaust out the muffler, piston to bore clearance problems out the oil filler hole) if you can determine what's normal leakage or abnormal leakage?

Take the cylinder head off again and look if there are signs of anything leaking out past the head gasket. (My H60 tested fine when cold but warped when it got hot) Mine did what yours does - runs fine until u put a load.

Another possibility - the cam might be off a tooth? but i assume you looked turning the crank with the head off to see if the timing looks right.

When u hook up a air hose into the plug socket and it will sound like it is leaking like crazy from the air passing the piston rings. While that is normal, at least you can hear if the valves are really seating or the cyl head is leaking. If you do this, turn so that the piston is at BDC so it doesn't jump when u give it air - dont want it to jump when u do.

You could measure the piston diam vs cyl but if u dont hear major piston slap when it runs, i would put this low on my list of possibilities.

Good luck.

Yes the timing marks is right. Outsider will that just be a air hose with 80 lbs blowing in the cylinder.???? You could be right. I know when i got this tiller off a guy,,,,That thing was running wide open. He told me it has been sounding like this for 3 years.,,,RPM should be around 3200 to 3400.,,Thanks

I dont have a leak down tester. For got to mention,,,greg