Idles great but...

[woodlandfarms]

Beyond the engine issue, I wanted to mention treadle control. Remember the more you mash the treadle the faster you will go but with less torque. You want to pull that stump or go up the steep hill the less treadle you should use. I forget this constantly, mashing the pedal to achieve great force only to realize I hid to lighten up to get moving.

 

[MossRoad]

No, when driving at full throttle she bogs down, treadle down all the way maybe going 3 mph. Something is wrong. Just can't figure what it is. A couple hours later I got on it and she acted normal for a few minutes. I thinking maybe something with the carburetor. What would cause it to repeatedly backfire while running?

I'm going to agree with Tim_in_CT and suggest you check the valve adjustment.

 

[Frank Sorbello]

I had the valves adjusted by a very reputable small engine mechanic less than two months ago. If I can make an attachment to help me lay wire with it, I think I will put a new engine in it. Somedays it runs strong, doesn't backfire, starts right up, runs smooth. The next day, the complete opposite. I've had quite a few people look at it and try to figure out what is wrong with it. It is very inconsistent. The fact that it was just rebuilt in the fall and has these issues has me wondering if it is even worth putting another nickel in the motor.

 

[BobRip]

I had the valves adjusted by a very reputable small engine mechanic less than two months ago. If I can make an attachment to help me lay wire with it, I think I will put a new engine in it. Somedays it runs strong, doesn't backfire, starts right up, runs smooth. The next day, the complete opposite. I've had quite a few people look at it and try to figure out what is wrong with it. It is very inconsistent. The fact that it was just rebuilt in the fall and has these issues has me wondering if it is even worth putting another nickel in the motor.

I may have missed it, did you check the ignition coils?

 

[Frank Sorbello]

try running some Sea foam in it before you change the plugs.

Do you think Sea foam will help? How much should I use?
Thanks

 

[MossRoad]

Do you think Sea foam will help? How much should I use?
Thanks

Sea foam is a fuel treatment. If your tank, filter, lines and carb are all clean, sea foam will not help. It will not hurt, but it probably won't help.

Backfiring is usually timing related, valves not opening and closing properly, etc...
Have the compression checked.
Have the valves adjusted again.
Have the timing checked.
Change both spark plugs, both plug wires and check the coils.
Fresh fuel, fuel filter and clean out the bowl in the carb.

 

[washita]

sparkplugs can be cantankerous, I have had plugs misfire under a load only, misfire because of oil/grease on the ceramic under the high tension wire boot, a hairline crack in the boot will cause a misfire also, abrasion on the high tension wire will short out the spark also especially under load, start your engine at night while dark and watch for a blue spark to ground or a halo effect around your high tension wires it will indicate a short to ground and the biggest mistake I have seen is trying to fix high tension wires with electrical tape it does not isolate high voltage