Tecumseh 8hp, hmsk80, surges

[sgkent]

I think he said that when he put the same carb from another unit on it the problem went away so he is replacing the carb and being done with it. Guessing he checked the intake runner for cracks.

Looking at it last night I got the idea that my snow blower has the same engine, just older
Swapped the carbs and intake runner
It ran perfectly

Ya replacing the carb is where I landed on this to.
Thanks

 

[t.ca]

Yes I reset the governor
Also I used both intake runners, mine and my buddies on both carbs
No matter which runner I used with his carb it surged
Both runners and my carb ran fine

 

[VegetiveSteam]

Is there a tension spring on the low speed circuit screw?

 

[Rivets]

I’ve reread this thread and see you’ve only adjusted the high speed mixture. Try this carb adjusting procedure, which I’ve used for years And still use it anytime I come across a carb with both idle and high speed adjustments. Once completed reset the governed top speed at 3250 RPMs. Just might work for you.
Adjusting a carb

This is the procedure I always taught my students to adjust a carb with two fuel controlling needles.

1. Start the engine and move the throttle control to top speed.
2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts to bog down.
3. Back the needle out 1/8 turn, the engine should now run smoothly.
4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn, restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed screw slowly out until the engine seem to want to die and then in 1/8 turn.
5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an RPM you like.
6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point and go to step 7. If it speeds up, repeat step 5 again.
7. Turn idle needle in until the engine bogs down and then out 1/8 turn.
8. Now the engine should run smoothly at all speeds.
9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not
come to speed, open the idle needle 1/8 turn and repeat.
10. Set to go.

There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure