Ok, so I've got this bike all put together and it had been running great. Would start first pull pretty well every time. Well, lately it has been quite difficult to start, so I checked some of the usual things. Pulled the plug and it was quite black, seems to be running overly rich. It seems to run fine--when it's running! I don't know if anyone else has done this before, but I am running a Tec carb on this 3 horse briggs. It fit pretty well against the head, but I'm just wondering if I've got a carb/engine setup that is not compatible? I've tried leaning things out but I just can't get it to run quite right if I set it too lean. I've got the high side and idle side out 1 1/2 turns approx. I attached some pics to try to give a better idea of what carb I've got--if needed I can get better/more detailed pics of the carb...these were previously posted pics! Thanks for any help.
My 'hybrid' briggs
- Thread starter matstang
- Start date
Don't know the sizes involved, between stock carb bore and the Tec carb, however it is possible that you have too much carb for low end [and possible mid range] performance. A carb works its magic of mixing air and fuel in the proper ratio at all throttle openings by getting a "signal" from the intake tract created by the piston producing negative pressure....vacuum. If the intake track through the venturi of the carb is too large [air speed too low] the signal will be weak. Not enough vacuum to tell the carb what to do. Fuel metering gets fuzzy. Maybe by putting the stock carb back on and cleaning the plug will improve the drivability and confirm if the Tec is too big. Good luck.
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When I rebuilt the carb, I made sure the float wasn't full of gas, then adjusted it level (turned carb upside-down made sure the tang was bent so that the float stayed level). Would a high float level happen if that tang was bent too far down (with it upside down)? Man, how confusing is that...? Does that mean it would be allowing too much fuel into the bowl?
The float being level [when up-side-down] does not mean that is the correct adjustment for that carb and/or for its intended application. If the fuel level in the bowl is not, more or less, at the correct heigth you will often have trouble adjusting a big flat spot out of the mid-range or too rich on the upper end.
It is possible that you are really fat at mid range. Try lowering the fuel level in the bowl [bend tab on float] and then see if the high speed adjustment can be richened? That's what I'd try at this time. I'd also put a new plug in it. Not so long ago I fought a 5 HP all day trying to get it to run right. Put a different coil on it then a different carb. Still the same problem. Then I changed the plug and all the problems went away.