18hp briggs twin cylinder opposed power problems. PLEASE HELP!!!

I have a 18 hp briggs and stratton 2 cylinder opposed engine. it runs and idles ok... i guess... i have to run it with about a third of the choke pulled out otherwise it dies. when ever i put it in gear and go it kicks and all power gos really low and the engine sounds like its going to die but then it keeps going but i only get half or a third power and it runs really slow. have any ideas why this is? or what i can do about it?

You could be running on one cilander, ik that those coils like to go bad, it may have a spark but could be a weak spark, or it could be fuel related issues, dirty carb, or bad air to gas ratio, soulds like its running on one cilander

ok so how do i check to see if it IS running on one cylinder? also how do i fix the spark? and hopw do i fix the bad air to gas ratio?

Well to check the sprk, its the easyest, get it running, take a plyers and pull one of the spark wires, it should keep running but rough, if its only running on one cilander it will die, do the same for both, to start out with, let me know what happens, dont use ur fingers, sparks hurt, lol

To see if its running on on cil

ok thanks ill try that today. now im gonna guess that it does have a bad gas to air ratio because i got it used and it was in pretty bad shape. how do i fix THAT?

Need to carefully and fully clean carburetor, especially if it has been sitting for a while, or take if off and have a mower shop clean/rebuild it.

Pull plugs, and lay them against side of engine so they are grounded to engine. Crank engine over like you are starting it, should have a nice blue sparks from both plugs. Don't hold on to them with you hands, they will shock you.

Put new plugs in.

ok. so the plug trick will test that and the carb rebuild will fix the air to gas ratio right?

also i have some questions about a old tecumsah rotortiller/snowblower combo. is there anywhere HERE i can ask about that?

should. If it doens't spark on both new plugs, the coil is shot. I've had 2 of the opposed coils die on me.

can i rebuild or repair a coil?? or do i have to buy a new one?

fletch6393 wrote:

can i rebuild or repair a coil?? or do i have to buy a new one?

U have to buy a new one

bummer. im flat broke. if i keep running it without replacing it will i blow the engine?

it will not hurt the engine in anyway and i can tell you its not the coil it sounds like its the carb because it wouldnt be running if it was the coil ive gone thru 2 coils but they where china coils i got a OEM briggs coil and my engine runs great aftea ton of mods done to it lol but anywho its your carb now get your self a carb rebuild kit that matchs your engine numbers those numbers are on the shroud and dothis inside your house at the table under a bright light s you can see if you drop any parts you can see where they land ive rebuilt my carb eh once and it started to act crazy again then i just bought some carb cleaner and i hanvnt had the problom again

jay it can still be the coil.....

My opposed does the same. Have to run it with choke on to idle. Runs hell good though. Turns 4000 rpms. Also the intake ports and exhaust ports of the motor could be clogged up. Never know.

xxXMowerdudeXxx wrote:

jay it can still be the coil.....

if it was the coil it wouldnt fire at all due to so much fuel goin into the engine at choke it would just stall if he has to run it with choke thas a carb problom and those coils are made where both pistons spark at the same time

yeah i dont know. im trying to do this as cheap as possible.

fletch6393 wrote:

yeah i dont know. im trying to do this as cheap as possible.

just rebuild the carb and your probloms should be cured

I'm pretty much on board with Jay Rod. Sounds like your carb is stuffed. A good cleaning should to the trick- try it before you order a rebuild kit. I have serviced a LOT of carbs, and very, very rarely do you ever actually need a kit. The first place to look (in your carb) is the main jet. Carefully poke a bit of fine wire through it to make sure there's no debris in there.

While you're at it, make sure that your fuel filter (if you have one- and you should!) isn't bunged up. Also keep in mind that there's a diaphragm-style fuel pump on the front of your carb, and it IS possible that it's time to rebuild it. For that, you WILL need a kit.

how old is this mower also check for cracks in your fuel line if you got a few dry rotted cracks then i think the inside of your fuel line might be falling apart and could of cloged the fuel pump or one of the jets

whats up?

Just a note, I've had these twin wire coil's go bad, and the engine still kinda of ran/started, just really poorly.

Stretch44875 wrote:

Just a note, I've had these twin wire coil's go bad, and the engine still kinda of ran/started, just really poorly.

ive had mine go bad on my monster opposed twin and started but i had to keep the throttle maxed out or it would die it wouldnt even idle so im pretty sure its his carb ecause he has to use choke or else it dies so that should tell you that its starving for fuel

Stretch44875 wrote:

Just a note, I've had these twin wire coil's go bad, and the engine still kinda of ran/started, just really poorly.

The carb is the first place to start. However, I have seen situations where a high tension coil wire breaks internally with no evidence on the outside. There are repair kits available for breaks mid wire, but breaks at the coil itself require more work. This is a common issue on old bikes.
I've seen vids of guys that have gouged out the epoxy from around the wire, and soldered on new leads, then re epoxied the hole.