I have had my 48cc Grubee Starfire engine for 3 years now, and it has 2000+ miles on it. It ran very well, only ever having carburetor issues until today: I was driving down the road and I felt the engine grab a little bit, loosing power for an instant at speed. My bike hadn't been staying in idle. It would stop suddenly after idling for a little while, even though it didn't sound like it was idling rich or lean. On my way back, and 50 feet from my house, the engine stopped, and I felt a heavy drag on the rear wheel, nearly locking it up. I pulled in the clutch and coasted to a stop in my driveway. I parked the bike and came back to it an hour later (after the engine cooled off). I pulled the head off of the engine to see if there was anything caught in the cylinder because I heard a scraping sound when the engine died. The sparkplug was a healthy dry brown color. I looked into the cylinder, and it was immaculate the sides shined like new and there were no scratches or any other signs of wear. I then engaged the cluch and gently rolled the bike back and forth with the head still off. Going forward, the piston went for half a cycle before I felt a snag and heard a quiet scraping sound, upon feeling the drag I reversed direction, this time the piston went for 3/4 of a cycle before I experienced the same snag and scraping sound. Since the cylinder is immaculate, and the drive/clutch gears are working perfectly, I believe that the problem stems from a seized/thrown bearing inside the bottom end. That said, I can't be sure until I've pulled apart the bottom end and seen for myself. If you think that it could be something else, please let me know.
Now for the crux of my post. If indeed this problem boils down to the innards of the bottom end, I need to know if a 48cc Skyhawk's innards are compatible with those of a 48cc Starfire engine. If the answer is no, where can I find parts for a 48cc Starfire? Since everything else on this engine is in full working order, I would much appreciate it if you could direct me the best way to go about fixing my Starfire rather than replacing the engine entirely. I will do everything in my power to fix the Starfire, as it was the first engine I ever installed on a bicycle.
Thanks for the info and advice,
Rambler
Now for the crux of my post. If indeed this problem boils down to the innards of the bottom end, I need to know if a 48cc Skyhawk's innards are compatible with those of a 48cc Starfire engine. If the answer is no, where can I find parts for a 48cc Starfire? Since everything else on this engine is in full working order, I would much appreciate it if you could direct me the best way to go about fixing my Starfire rather than replacing the engine entirely. I will do everything in my power to fix the Starfire, as it was the first engine I ever installed on a bicycle.
Thanks for the info and advice,
Rambler