Runs Rich with Air filter
Hello all. I recently picked up a old Generac Model 1647-0 Power Boss 8000 watt generator on Let Go. I needed another hefty genset and couldn't pass it up for $40. It had been sitting outside(for years) with no wheel kit, missing air cleaner, recoil starter etc. It was mess but I just wanted to tinker with that Twin cylinder 18 HP Briggs. Cleaned it all up and pumped the water out of it. Yes, cylinders were full. Oil looked OK but changed it and the filter anyway. Cleaned the carb, intake and head up and re installed the exhaust valve pushrod on the cyl 2. It just came off the lifter and was sitting in the engine. Adjusted the valves and cleaned up the tank and fired her up. She had a miss in both cylinders so I changed out the plugs and mags. This was with no air cleaner mind you. I loaded it up with a couple space heaters and flood lights for about a 1/4 tank and she ran strong. Now, here is the kicker. As soon as I installed the air cleaner and filter she loaded up and started missing fierce. No smoke but you could smell it. I had previously disassembled the carb and cleaned everything I knew, including removing the main jet and float/needle. I did not remove the mid range jet/nozzle. I didn't have a screwdriver that size and didn't want to damage the body.
My question is, is it possible the Mid range jet/nozzle is clogged and the engine is pulling fuel through the HS jet instead when I install the air filter and in essence, choking the engine with HS fuel metering at midrange speed? This has been a blast and that Briggs is smooth, so far. Just can't run it without the air filter. Thanks for any insight.