bogging out

[lawngnome]

24hp extended life briggs. Rebuilt carb,new plugs, adjusted valves and govoner, good compression on both cylinders, Seloniod on carb is working.

New spark plugs are black from unburnt gas after little running time.

When i throw the throttle from the lowest to the highest the engine boggs out than starts spit black smoke,thus flooding out. Can bring it back to lowest position and it will smooth out. Now if i move slowly to the highest it will run at full throttle. While at full throttle turn blades on, will bog out spitting black smoke. If i put at half throttle turn blades on, than slowly move to 3/4 throttle it will run like that for 10 or so mins than start to bog out. Or until i try and go up a hill.

Whenever it bogs out i can return it to lowest throttle and it will always smooth out.

I am completely lost, and at my ropes end. Any help would be great. I am considering taking it to somebody which really bothers me.

 

[Rivets]

I would go back to the carb. I think that the symptoms point to something wrong with the float. Check to see that the float level is set properly. Turn it upside down and make sure that it is level with the carb body.

 

[lawngnome]

Its a plastic float. So it cant be adjusted i think. Guess it would be a replace a part deal. And thank you

 

[DaveTN]

Its a plastic float. So it cant be adjusted i think. Guess it would be a replace a part deal. And thank you

Other than the float making the engine run rich, just wondering if you have checked for a choking problem? "If" the carb float is set properly , the richness could be leaned out with adjustment screw. Some sort of intake restriction could also be acting like a choke on full or 3/4 etc. Hope this helps. Dave

 

[lawngnome]

Choke is operating correctly. The rebuild kit offers a restrictor, i didnt install it. Gonna locate mixture and try that. The only way to fix float, if problem, is bending plastic . When start bogging sometimes i can let it keep spitting and it will smooth out. Almost like there is an accelator pump,like in vehical carbs, and it dumping to much

 

[Little John]

You've got too much gas at full power - If it was my motorcycle, I'd say you need to drop the needle down one click or get a smaller main jet. I don't know much about carbs on these guys, though.

 

[Rivets]

Back to step one. Spitting out fuel at full throttle is not all bad, most carbs will do this, but the black smoke concerns me. At this point I am assuming that the flow is set so when you invert the carb it is level with the base or tipped up slightly going away from the float pin. Do you have a single handle throttle lever? One where you push it all the way forward and you choke the engine, once started you pull it back about 1/2" to the top speed. If so check that adjustment to make sure that it is coming off choke. Also, please post the model numbers of both the engine and unit.

 

[lawngnome]

Engine # 44m777 type 1091b1

Mower model 917.288700

The choke is a seperate pull handle. Yes the float is set correctly(as far as i can tell without machinist rulers)
It a platic float and so out of adjustment, would have to happen manually(plastic getting bent). And float maintain boauncy(floats) in water a cup of water. I let it float in water for an hr than shook it and passed.