Originally Posted by Me and my monkee
I remembered a top speed of just shy of 70 back in the day, but this one can barely crack 55 on a flat road. Though my old one did have a Micron race pipe
I got all the intake system back to stock but felt the bike bogging in the last 10% or so of throttle. Removed the airbox silencer to let more air in and it ran like pure shit, sputtering and all. Put a piece of uni-foam in the circular intake on top of airbox, without the airbox silencer (this is how it was when I bought it) and things got better. Better throttle response, and better top end, but barely.
I just want to get it running right, and then worry about tuning etc. after that.
I have not checked jet sizes yet...I guess I need to do that first, make sure the carb is all stock. Carb needle looks very straight, hardly any taper at all.
Crankcase seals? Easy fix?
How much did you weigh "back in the day?".... If you put on 100 lbs, that poor little bike is giving you all she's got at 55....
To check crankseals, you'll need to do a leak-down test. Blocking intake and exhaust ports, making sure everything is tight (head, carb manifold, etc)... Pump in 6 lbs (hand pump..NOT A COMPRESSOR) of pressure, and if it holds for 6 minutes, you are good as far as "pressure" goes. Then use a mity-vac and put 6lbs of vacuum to it.. If it holds for 6 minutes, the crank seals are good. If it doesn't hold on either test, squirt some soapy water on "suspect" areas to see if there is a leak in a location other than the crank.
Im not sure if you can replace the AR80 crank seals without splitting cases? If you can, then yes... pretty easy fix. But if they are "ribbed" seals (where the cases hold them inplace), then you are stuck splitting cases.
Probably not a bad idea to buy the Sudco Mikuni Carb Tuning manual.. It will teach you about each carb circuit and its job in fuel/air delivery.