DuraForce Exhaust Question

You might have a leaking inlet valve in your carb that is leaking fuel mix into the engine and then down into the exhaust cleanout chamber. Do you have a fuel line shutoff valve and if so do you use it? I let my DF run out of fuel if I intend to quit mowing for the day by shuting off the fuel valve and letting it run out of fuel. Does it smoke alot when it is surging? If so it may have a rich surge condtion instead of a lean surge. They sound the same the only difference is the rich surge smokes a lot. If the DF has a bad surge then I open up the main one size and give it a try, if it still has a bad surge then I go the next size drill. If the first drill size makes a big difference then maybe you can open up the low speed one size to finish it off. Be sure to let it fully warm up before increasing the jett size as it can take up to 15 minutes to get fully warmed up. If you just open up the low speed jett then you run the risk of being too rich on the low throttle settings, which can cause it to "Load Up" if you let it idle for a bit. Make sure there are not gasket or seal leaks that can cause the surging conditon due to sucking air past the gasket/seal. Good luck! Your efforts will be rewarded!