Lawnmower Problems

Lean fuel conditions certainly can cause a surge.

Before I change jetting, I would check the Governor. If this mower has a mechanical governor like my push mower, when they get worn or even dirty they can cause the engine to surge. It's like the throttle position gets "out of sink" with the RPM.

Many industrial engines have governors but I was surprised to find one on my push mower.

When it comes to drilling jets, I did this to a dirt bike that was very lean from the factory and achieved cleaner throttle response. Start with a very small increase in size. Remember, you are dealing with an increase in the cross sectional area so a small diameter increase will have a large affect.

Very likely the Govenor tension spring needs to be attended to. Check attachment tab for bending or loose mount or interference by dirt or matter. Probably need to increase spring tension. Small amounts at a time when you establish if + / - tension is needed.

Well, if he is 96 hi's not a boy anymore, so try to be easy on him.

To avoid surges keep him busy.

I don't understand the last part of your post, if it was boring the first time, why do it again?

I'd try tiny increments on the drill bits, 'till desired performance is achieved.

Yahlasit

"if it was boring the first time, why do it again?"

-Guest

lol

i did somthing similar to this when i converted my propane BBQ to natural gas.

Bore the jet one drill size at a time. (ex. if a #12 bit barely fits in there just step it up to a #11). over boring it will obvesouly cause it to run rich and may cause loss of power and maby stalling all together.

good luck

I don't reccomend jet drilling. I have found that the govenor spring is usually the cause, from loose, dirt, bending or weak. On a mower I have, I intentionally caused this recover from really deep weeds and grass, allowing it to run wide open a bit longer.

Thank you all for the tips. I'll start with the least intrusive and give the carb a good cleaning with attention to the governor. If that fails, I'll move on to the pun-laden activity of boring the jets (my banjo playing usually does the trick).