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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 28354
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a Snapper riding mower with &S intek 12hp motor.

Customer Question

I have a Snapper riding mower with B&S intek 12hp motor. It starts and idles great. When you speed up, the governor hunts back and forth. I have checked the valve clearance, new plug, new air filter, checked the fuel cap vent, cleaned the carb. What am I missing? Bob O.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

Is there a fuel filter between tank and carburetor> Do you have good flow to the carburetor?

Customer: replied 1 year ago.
Expert:  Curtis B. replied 1 year ago.

Yes, fuel filter? Was it changed? Does engine have any power?

Customer: replied 1 year ago.
Not sure when it was changed. The engine does not seem to have much power when you speed up the RPM. It hunts back and forth.
Expert:  Curtis B. replied 1 year ago.

The hunting is sign of lack of fuel, so changing the fuel filter should be first thing to try.

Customer: replied 1 year ago.
I'll do that and get back with you tomorrow. Thanks
Expert:  Curtis B. replied 1 year ago.

OK> thanks

Customer: replied 1 year ago.
I changed fuel filter and drain the gas tank to make sure there was no obstruction. I started the engine again with the same result. It's fine at idle but the governor hunts when I accelerate. Any other suggestions?
Expert:  Curtis B. replied 1 year ago.

Is this gravity flow or is there a fuel pump between tank and carburetor. This is OHV engine, have the valves ever been adjusted? .004 to .006 inch intake and exhaust.

Customer: replied 1 year ago.
This is gravity flow. I have checked the valves twice.
Expert:  Curtis B. replied 1 year ago.

With this being gravity flow, for test, remove the fuel filter and test.

Customer: replied 1 year ago.
OK. Back to you later.
Expert:  Curtis B. replied 1 year ago.

OK>

Customer: replied 1 year ago.
Sorry it took so long. I had to make a trip to parts store for fuel line (15 miles each way). I tried it without a filter or shut off. No change. I will mention that when the engine is hunting I hear a sort of back fire thru the air intake. Ihave the air filter off while I'm working .
Expert:  Curtis B. replied 1 year ago.

?? And valves have the correct clearance. It is possible that you have a valve that is not seating! Would show on a leak down test, but not compression test.

Customer: replied 1 year ago.
What does that involve? Sounds like a lot of work.
Expert:  Curtis B. replied 1 year ago.

It takes and air compressor and adapter with gage, where you put air into cylinder, and then shut it off, to see how long it holds pressure and where any leakage shows up, as through the valves or the cylinder!

Customer: replied 1 year ago.
I don't have that equipment. Any other way?
Expert:  Curtis B. replied 1 year ago.

I doubt it will help, but try to add a small amount of tension to the springs on the carburetor linkage. Do not add much, as added tension will change maximum rpm.

Expert:  Curtis B. replied 1 year ago.

Most auto supplies would have a leak down tester to rent.

Customer: replied 1 year ago.
OK, I'll try that. I'll check with auto supply for the tester. Back to you later. Thanks
Expert:  Curtis B. replied 1 year ago.

OK>

Customer: replied 1 year ago.
I tried putting tension on the governor spring. It seemed to help some but not completely. I have not had any luck renting a leak down tester. I ordered one on Ebay. May take a week to get it. Anything else that I can try at this point?
Expert:  Curtis B. replied 1 year ago.

The governor lever can be moved on the shaft, that goes inside the crankcase. but it is very sensitive to any change. It you want to try moving the lever on the shaft, mark the two parts with a scribe before loosing so it can be put back to it's original position. The lever is loosened and the shaft has a split end , that lets you turn the shaft in tiny increments, one way or the other to change governor setting.

Customer: replied 1 year ago.
Which way do I turn it?
Expert:  Curtis B. replied 1 year ago.

Its not a certain, try one way and see it fit gets worse or better.