ive got a 66cc grubee Skyhawk kit. its got 400 miles on it. its been running great. it started losing power gradually and I found the air filter was getting clogged with oil. I sprayed it with some brake cleaner and compressed air and it worked fine. the other day I took it on a long ride and it ran fine but noticed a small power drop,(usually goes about 22-23 mph) but was struggling to get to 18 mph. so I figured the air filter clogged again so I took it off and still same problem. I did a test run after it cooled off and the thing wouldn't go past 14 mph. it runs decent with the clutch disengaged but its a dog engaged and will hardly move at all. 1. I replaced the spark plug 2. I checked and adjusted the clutch 3. adjusted the clutch arm (pulled the cable about 1/4" tighter) 4. checked the magneto 5. checked the wiring to the cdi 6. took the head off and checked the piston and cylinder 7. drained the fuel and replaced with new oil gas mix about 25:1 8. checked vacuum on carb (seems to be pulling a good deal of air) there was a small nick and some thin scratches at the top of the cylinder (about 1/8" from the top) the head gasket didn't seem to be leaking. piston moved up and down freely and smooth. I took the carb bowl off and looked inside everything seemed ok and clean. I checked the choke and throttle operation and they both seemed ok. my exhaust baffle had fell off so I made a new one out of sheet metal, I thought it might have been clogged so I took it off, and still same issue. I thought the choke cable might have been sticking so I checked it and that was ok. could the cdi be going out? I figured since it runs good with clutch out it was ok could it be the carb? also thought it was ok since it runs good with the clutch out. clutch problem? it engages and disengages fine too. I cant seem to figure out why I have no power. any info would be appreciated, got to get this dog back on the road again .