from Asheville, nc
Second, it sounds like your clutch is slipping under load. First make sure the clutch cable isn't to tight, and second try a good dose of seafoam in the oil and run it for a few miles and then change the oil and filter. If you still get the slippage, then its probably time for a new clutch spring. There are several different choices out there.
If you do a search for clutch spring here on the forum you will get all sorts of info since this is a very common issue.