roughrunningatfullthrottle

[johnmetcalf]

I have a allischalmers b that run good at idle but misses at full throttle while mowing with a l59 woods. unless the choke is closed slightly. what could be the problem.

 

[Mike(NEOhio)]

Check for a fuel flow obstruction.

 

[old]

You could have problem with the carb and the main jet is clogged up some. If I remember right the B did not have an adjustable main jet but has a sort of cap/plug over it. One can remove that plug and turn on the gas and watch fuel flow out of it. You need a good steady stream and if taking a small wire or as I do a torch tip cleaner tool and poke it out and have the flow be better then good chance you have some rust/dirt In the carb that needs to be cleaned out. Some times pulling the carb drain plug out and letting gas to flow for few minute can help as can running it with the air cleaner tube off and then put your hand over the end on the carb and pulling it back off a few times. Do you best not to let it die doing that. Also if I remember right pulling the air cleaner tube off takes removing the air cleaner which is a good time to clean and service it

 

[Dick L]

Other things that can cause it to run rough at full throttle and seem to idle fine is, point gap, spark plug, crack in the distributor cap or weak valve spring to name a few. Most of the time it will be fuel restriction somewhere. Starting with checking fuel delivery from the tank to the firing chamber is where I would start. A bad spark plug can give you fits also. I have had plugs be fine under light load and give out under heavy load.