MrStubb
XS400 Addict
Wonderful!!! I really can't explain why this would help your issue yet. I know that the original intake system on mine (1980) looks to be kind of restrictive. I'm thinking pod filters when I can get to it. Speaking from experience with my 71 Chevy. Carbureted engines need to breathe really well both intake and exhaust to reach their potential. Any restriction on that engine either way would cause lost performance and poor fuel economy. After I rebuilt that engine it had a tendency to draw oil vapor from the crank case with the stock air filter. It had to do with the mid range cam we installed. We installed a small filter on the crank case vent. It all seems to come down to breathing. I have also seen where a small rodent (mouse) took up house keeping in in the air horn of one car's air cleaner. That little bugger made it seem the choke was closed causing a rich condition and really poor fuel mileage. I've got to get some sleep for my 3 am wakeup. But before I go Be proud I am. You're not some dumb college student. You've gotten further than I did (college? me? barely got thru high school). And thru the process of elimination and good advise from many others not so much mine. You have narrowed down the problem. Watch your oil. Never run with out some kind of filters on all 3 (2 carbs and crank case vent). And Drive Carefully.