my 77 puch just got fresh top end,clean carb,set points015,new plug,run35mph flat land once you hit small incline wont pull the hill.my sport78 puch will pull hill good.live at 6000 ft.i had a 62 main jet in the 77 so i took 58 jet out of 78. didnt work wood not pull at all.put 62 main back in runs fine on flats. i checked plug color its tan.40 to 1 mix.i checked clutch basket tight pads ok.now it did the same thing before rebuild. just wont pull on a hill. motor wont rev up till you get going.any help?