Rider Mower Issues - Briggs & Stratton Engine

[Slow Joe]

Alright, I'm not the man when it comes to lawn mower engine issues. I have a late 90s (99, maybe 2000) Craftsman rider with a Briggs & Stratton 20.5 Twin Cylinder Engine. It starts fine and runs good... Until you put a load on it. At that point it either dies off (if it's in higher rpms) or if it's in lower rpms it runs, but runs shitty.

My guess is that it needs some carb tuning? Maybe a rebuild?

I just bought it in spring, and when I bought it I put in two new plugs, a new fuel filter, fuel line, and I've been running premium gas in it.

Any ideas??

[nismodave]

Hire Mexicans.

[Russ Jerome]

Under load but runs fine I would agree its basic, plugs/ fuel/ carb. Do the stupid stuff, even air filters even tho they look good effect little 4stokes far more than our cars. With good fuel, plug and air filter let us know, carb cleaning is easy repair for minor beer charges.

[michelle]

Bring it over.

[Slow Joe]

Hire Mexicans.

Uh, no.

Under load but runs fine I would agree its basic, plugs/ fuel/ carb. Do the stupid stuff, even air filters even tho they look good effect little 4stokes far more than our cars. With good fuel, plug and air filter let us know, carb cleaning is easy repair for minor beer charges.

That's kinda what I thought...

Bring it over.

I'd have to steal my dad's trailer, but when do you think? I'm pretty busy for the next week or so though

[BAD LS1]

Opposed twin... Well judging by your symptoms you listed, you guessed it, the carb needs some attention. If it all of a sudden started doing this then fuel deposits are probably at fault. Doesn't take long in this heat for fuel to go cowshit. Why premium in something with a 8.0:1 compression ratio?

Typically if it runs like shit under load, your high speed circuit is at fault... But you say it's also garbage too at idle, so sound like double whammy, reinforcing the fuel deposits theory. These engines actually spend almost all their time on the idle circuit even at full speed until sufficient load is placed on the engine allow the governor to move the throttle plate off near idle and over to fuel delivery from the main nozzle.

[michelle]

I'd have to steal my dad's trailer, but when do you think? I'm pretty busy for the next week or so though

Whenever. How wide is the deck? I can always grab it with my little trailer. I rather not haul around my car trailer if I don't have to.

[Slow Joe]

Opposed twin... Well judging by your symptoms you listed, you guessed it, the carb needs some attention. If it all of a sudden started doing this then fuel deposits are probably at fault. Doesn't take long in this heat for fuel to go cowshit. Why premium in something with a 8.0:1 compression ratio?

Typically if it runs like shit under load, your high speed circuit is at fault... But you say it's also garbage too at idle, so sound like double whammy, reinforcing the fuel deposits theory. These engines actually spend almost all their time on the idle circuit even at full speed until sufficient load is placed on the engine allow the governor to move the throttle plate off near idle and over to fuel delivery from the main nozzle.

I use premium since I keep it in the gas can just in case one of the cars runs out, plus I've always figured it's "better" for it since it's running at high RPMs. Oh and thanks for the heads up Tom. I figured I'd run into some issues looking at the last owner of it

Whenever. How wide is the deck? I can always grab it with my little trailer. I rather not haul around my car trailer if I don't have to.

42" Deck. I'll have no problem stealing my dad's trailer, and I know it fits in there since that's the way it got here. Plus I can use my "truck" to get it there..

[michelle]

Haha, your truck. I saw that.

[stenchmiester]

possible valve clearance issues otherwise

[BAD LS1]

^^^ or the valve seats are hanging out of it!! It is an opposed twin after all!

[Slow Joe]

Well, that doesn't make me feel good about it... I'd rather hear that it's the carb... I'm going to start there...