Not a expert but your new chain will stretch some for awhile under load. You might want to mark your carrier and the swing arm to see if the carrier is turning inside the clamp. If not then I would suspect the swing arm bearings or the carrier bearing like badasskfx mentioned earlier. Jmo
Parts for sale
85 KX250 Roller with engine
KDX motor
2004 E-Ton Viper 50 Needs work
Honda 87 Fat Cat Roller
Honda 200m motor
Honda 110. 80 frame 82 motor For parts. Runs.
Honda 84 ATC 70 Roller Cheap.
XR75 complete bike
XR80 parts
Yamaha 225dx parts.
Honda 84 200es parts Good bottom end. (quad conversion front end)
Kawasaki 93 KX80 Motor (needs piston & bore)
Yamaha 88 YZ125 cases
Suzuki 85-87 LT230s 2 complete parts bikes.
Honda 83-85 200x Parts
Honda 86-87 200x Parts