I was riding my brand new 1980 KZ 440 home today, I got it to blast up to 50-55 relatively easily for a smaller cc bike. Once I got it all the way up there it started to loose power, leveling off at about 40-45. I assumed it was because it was running out of gas, it has a small fuel leak from the petcock, that I will be replacing soon, I swayed the bike, and bounced on the front shocks to slosh the fuel around, and it felt like it gained some power again, just temporaraly, then back to the average. I was a little low on oil, so, that might be it. I may need a carb clean/tune. I dont know, please make some sugestions about what it might be and/or how to fix.....thanks!