Nevermind.

Nevermind.

Well, it's all pretty much done now.

My neighbor gave me a early 90's riding mower which needed work. I changed the oil, replaced the battery, the starter solenoid, the spark plug, the fuel line, the valve stem cores, and the blade, but it still would not run right. I was stuck, because I didn't know how to rebuild a carb, but my father was able to help me. Then a neighbor helped me adjust it, and it runs and mows well now, but won't quite run right if it's WOT, hot, and not moving or turning the blade. I think the govener may be out of adjustment, but that doesn't really bother me since it works.

if the timing is off just a little they run funky too.

I thought these small engines had fixed timing?

Most problems today are caused by fuel left in the tank or carburetor bowl. The 10% ethanol gas is wreaking havoc with small engine fuel systems...especially with machines that are only used periodically. Very recent engines are having issues with dumping gas into the crankcase as a result of needle and seat failures.

There's a good chance it will even out over time as you run new fuel through the system. Consider a shutoff valve if you don't have one already.

If it is an older machine you might have points and condenser to deal with as well. If you do have a points and condenser ignition, you can easily convert to solid state for very little money. The hardest part is usually getting the flywheel off.

I've noticed that my 2 stroke machines are not affected like the 4 stroke. I assume the oil mix fuel holds the active ingredients in fuel together longer than non-mix fuel effectively acting like a StaBil product.

Good luck,

Jay in MA

I thought these small engines had fixed timing?

Most problems today are caused by fuel left in the tank or carburetor bowl. The 10% ethanol gas is wreaking havoc with small engine fuel systems...especially with machines that are only used periodically. Very recent engines are having issues with dumping gas into the crankcase as a result of needle and seat failures.

There's a good chance it will even out over time as you run new fuel through the system. What you might be experiencing is "surging". In an otherwise healthy engine it is usually caused by some sort of restriction inside the carb. The jets sometimes have very small holes on the side that can easily get plugged. Consider a shutoff valve if you don't have one already and run a carb cleaner product in your fuel supply for a while. Governor adjustment is a very simple process but you need to know what you're doing or you'll blow the engine in short order. You need to know if you have the correct springs and/or rods in your carb linkage first.

If it is an older machine you might have points and condenser to deal with as well. If you do have a points and condenser ignition, you can easily convert to solid state for very little money. The hardest part is usually getting the flywheel off.

I've noticed that my 2 stroke machines are not affected like the 4 stroke. I assume the oil mix fuel holds the active ingredients in fuel together longer than non-mix fuel effectively acting like a StaBil product.

Good luck,

Jay in MA

I thought these small engines had fixed timing?

they mostly do have fixed timing, but the key can get sheered a little if someone hit something, that'll toss timing off just a hair and make it run a little funky.

i agree with the above about old gas. drop the bowl, clean the carb out with some deep creep spray (make sure and clean the main jet well), and run a tank of gas through with some seafoam and make sure it has fresh clean oil.

How would someone "sea foam" a lawn-mower engine? For example, the 4.5 HP B&S engine on my Craftsman push mower. How is the sea foam delivered to the engine? How much is needed? Where do you get it, and how much does it cost? What does the sea foam do? Please address all these questions.

My Corolla has no need for any such thing. My lawn mower is a different story.

you would insert a tube into the can, take the airfilter off, and put the other end of the tube in the carb throat and then manually open the throttle some holding the can about level or slightly above the carb. it'll suck some in and smoke a good deal, have someone let go of the bale bar as you raise the can higher and it starts to stumble. let it soak over night or for a few hours then start it back up.

it'll clean out carbon buildups, but only needs to be done if your engine is having problems like pinging or dieseling. if you're not getting those then it won't help to use it in that way.

the OTHER way to use it which may help you is to mix it in with the gasoline and run it through like that. that'll clean some carbon but mostly clean the carb and intake valve.

you would insert a tube into the can, take the airfilter off, and put the other end of the tube in the carb throat and then manually open the throttle some holding the can about level or slightly above the carb. it'll suck some in and smoke a good deal, have someone let go of the bale bar as you raise the can higher and it starts to stumble. let it soak over night or for a few hours then start it back up.

it'll clean out carbon buildups, but only needs to be done if your engine is having problems like pinging or dieseling. if you're not getting those then it won't help to use it in that way.

the OTHER way to use it which may help you is to mix it in with the gasoline and run it through like that. that'll clean some carbon but mostly clean the carb and intake valve.

My engine isn't pinging or dieseling, but it does occasionally run in surges, particularly when the mower is changing direction, as at the end of a cut row. When going straight down the row, it steadies out. It was a lot worse late last mowing season, even after replacing the spark plug. This year, before starting, I replaced the air filter, and it started on the first pull and ran a lot better, yet still surges somewhat.

I agree that the direct spray into the carb throat probably isn't necessary, but adding to the fuel might be beneficial. How much? How many ounces per gallon? How often should I run it thru?

run through a few ounces with each tank i guess, i just pour some in depending how bad it needs it.

as for the surging, replace the governor spring(s) may take care of that problem. the engine runs at speed which is a balance of the internal governor trying to close the throttle, the spring resisting, and then the stop being set to the minimum rpm you select with the lever. it'll open more under heavy load but not increase in rpm as the engine speed falls slightly and the spring opens it more. as the load goes away engine speed picks back up and the governor overtakes the spring tension and pushes it back against the stop.

more or less thats how it works, so you can see how if the spring gets weak it'll surge as the governor is able to pull the spring till the spring catches up and pulls it back, then relaxes, etc and so on. its worse if you suddenly jam the throttle lever up or down?

The following is from the SeaFoam website.

Seafoam can be found at most automotive parts stores like Advance Auto Parts for about $8 per 16 oz can.

It was basically developed for decarbonizing combustion chambers....probably for 2 stroke engines like Yamaha's Ring Free product.

How to Use SEA FOAM

In Tune-Up of Small 4 Cycle Carbureted Engine Lawn Mowers, Tillers, Edgers, Snowblowers, etc.

1. Start engine. If engine will not start, check spark and compression. If engine has spark and compression, pour a small amount up to 1/2 ounce into the carburetor throat. SEA FOAM will act as starting fulid and will start the engine unless there is a mechanical or electrical problem. With engine warm, keep on high idle and slowly pour one ounce through carburetor throat. Make sure exhaust is well ventilated when using in the carburetor as fumes will be extreme for a short time.

2. Pour 1/2 ounce to one ounce into small fuel tank and oil crackcase.

3. Immediate Results: Same as for large 4 cycle Autos, Trucks, Tractors, etc.

NOTE: One pint treats 8-25 gallons of gas (average one ounce per gallon) or 6-12 gallons of gas oil mix (average 2 ounces per gallon.) Does not replace oil. Use frequently.

For Small 2-Cycle Engines

1. Use procedure 1 of tune-up of small 4 cycle carbureted engines.

2. Pour 1/2 to 1 ounce into small fuel tank.

3. See label on can for exact detailed results for use in each area Fuel Tank-Carburetor.

NOTE: SEA FOAM does not replace 2 cycle oil.

http://www.seafoamsales.com/motorTuneUpTech.htm

How would someone "sea foam" a lawn-mower engine? For example, the 4.5 HP B&S engine on my Craftsman push mower. How is the sea foam delivered to the engine? How much is needed? Where do you get it, and how much does it cost? What does the sea foam do? Please address all these questions.

 

My Corolla has no need for any such thing. My lawn mower is a different story.

run through a few ounces with each tank i guess, i just pour some in depending how bad it needs it.

as for the surging, replace the governor spring(s) may take care of that problem. the engine runs at speed which is a balance of the internal governor trying to close the throttle, the spring resisting, and then the stop being set to the minimum rpm you select with the lever. it'll open more under heavy load but not increase in rpm as the engine speed falls slightly and the spring opens it more. as the load goes away engine speed picks back up and the governor overtakes the spring tension and pushes it back against the stop.

more or less thats how it works, so you can see how if the spring gets weak it'll surge as the governor is able to pull the spring till the spring catches up and pulls it back, then relaxes, etc and so on. its worse if you suddenly jam the throttle lever up or down?

My lawn mower does not have a throttle lever. There is no way to control the engine RPM; it is apparently governed to run at an optimum speed. I'll have to examine the carburetor to see just how the speed governing mechanism works. If there is some spring involved, I'd probably have to check the Briggs & Stratton web site to see if they have a service manual with a parts list. However, I cannot imagine anything having worn out already, this is only the fourth season on this mower. The engine probably doesn't have more than 60 or 70 hours on it, if that. I have a very small yard, with only around 4500 sq. ft. of grass to mow. The job usually takes about a half-hour. It is not unusual to be able to go for two weeks between mowings, since our summers tend to be dry.

theres a linkage and a throttle plate than you can maniulate, just because they don't give a control for you to do so does not mean that you cannot do it manually.

New gas....it doesn't cause varnish like the old days which is easily removed with a Gumout like spray product. The 10% ethanol mix causes corrosion of the aluminum / white metal / pot metal parts and it's sometimes not able to be cleaned enough to bring the engine back to its original running condition.

I doubt you have a governor problem unless you or someone else has been playing with the mechanisms. I've never seen those springs stretch unless they were misrouted and got tangled up in the linkages etc at which point they will also be disfigured.

If you do replace the springs you must get the correct springs from the manufacturer...close enough won't do in this situation.

Jay in MA

run through a few ounces with each tank i guess, i just pour some in depending how bad it needs it.

as for the surging, replace the governor spring(s) may take care of that problem. the engine runs at speed which is a balance of the internal governor trying to close the throttle, the spring resisting, and then the stop being set to the minimum rpm you select with the lever. it'll open more under heavy load but not increase in rpm as the engine speed falls slightly and the spring opens it more. as the load goes away engine speed picks back up and the governor overtakes the spring tension and pushes it back against the stop.

more or less thats how it works, so you can see how if the spring gets weak it'll surge as the governor is able to pull the spring till the spring catches up and pulls it back, then relaxes, etc and so on. its worse if you suddenly jam the throttle lever up or down?

My lawn mower does not have a throttle lever. There is no way to control the engine RPM; it is apparently governed to run at an optimum speed. I'll have to examine the carburetor to see just how the speed governing mechanism works. If there is some spring involved, I'd probably have to check the Briggs & Stratton web site to see if they have a service manual with a parts list. However, I cannot imagine anything having worn out already, this is only the fourth season on this mower. The engine probably doesn't have more than 60 or 70 hours on it, if that. I have a very small yard, with only around 4500 sq. ft. of grass to mow. The job usually takes about a half-hour. It is not unusual to be able to go for two weeks between mowings, since our summers tend to be dry.

i see those springs worn out often enough, but the machines are usually 10-20 years old and used pretty often. yes, they do need to be the exact spring though, as the tension works with the gov to keep the correct engine speed.

I had the same problem with my old craftsman. Seafoamed the crap out of it, replaced the gas tank fuel lines and fuel filter, cleaned the carb out yet still had problems. Got rid of it and now Im enjoying a new ride that works hassle free. Good riddance to the craftsman.