When you balance a set of carbs on a running engine you're adjusting the airflow through the carbs which can be affected by VERY slight differences in valve clearance, cylinder wear, valve condition, and just about anything else in the engine. Synchronising after rebuilding them is a good start but they need to have the flow balanced once they are reinstalled and running. Out of balance carbs are most noticeable at small throttle openings where slight differences in flow will make the most difference to the running. Properly balanced, they will reduce noises from the engine and clutch at idle as the two cylinders will be doing an equal amount of work. They will not be noticeable at wide throttle openings as such small differences will be a very small percentages of the total airflow through the carbs.
There are more variables to sync than just butterfly opening. Bench sync is a good idea after a rebuild if you took off your linkages and need to start over. This should allow the motor to run good enough to then throw the sync gauges on and get it right.
It was the middle springs. They get gunked up over time. Best to squirt WD40 on them, let it soak for a few mins, then you can toothbrush it right out. Wipe it with a rag, repeat if necessary, then a final lubricating squirt. Give it a few twists and it should have a new lease of life. Also put a little bit on the ends of that shaft, on the outside edges of the carb. Just rebuilt mine 😊
The throttle linkage was seized right shut on my shadow that sat for 3 years. I kept spraying wd40 in all the spots where the linkage moves and kept working it. Took like half a bottle of wd40 and my fingers were pretty sore but I got it nice and snappy after about an hour of flipping it back and forth.
hi .great video. just recently bought one of these bikes as a project. drove the bike 50 miles never missed a beat.however struggled to get over 60mph🤔ive also found the vacum pipe from the tank has been disconnected. a pipe where it should connect runs from one carb to the other.the previous owner said he has fitted larger jets .🤔cone race filters also installed. but the other day i kickstarted the engine and one of the carbs blew off on the left hand side that powerfull it took the fuel pipe off the tank tap.has this got anything to do with the vacuum pipe not being connected 🤔thanks
My last comment- I ment to say throttle valves and shaft. For some reason I said choke and shaft. ( It is important that both chokes are in sync. Just as the throttles are). I would like to send you a pitcher of a 1979 Kawasaki K Z 650, restoration I did in 1995. Also a pitcher of my 2009 Yamaha Touring deluxe I'm driving. I have not been successful sending them. Is there a P O box? Thank you. God Bless you.
