thanks for this insight. I have a service manual on the way, so will do some reading on the balancer timing process.
In the meantime I see there's a used motor at a junkyard across country along with an airbox. I'm thinking of purchasing both for spares and to rectify the pod filter installation. Any advice on purchasing a motor sight unseen?
If it was stored without sparkplugs, carbs, or exhaust, chances are you will have rust on the valves or in the cylinders and may need top end work. Buying whole engines is always a gamble.
I recently went through 4 engines for a GSX-R project until I got one that seemed OK until I got it on the road and realized it needed a new transmission. Sometimes the devil you know is better than the devil you don't. I think its possible to split the cases without removing the top end if it comes to that.
While the counter-balancer system is heavy and overly complicated on the KZ twins - it is effective. The same basic concept is in use today on KTM singles and twins - main difference is its gear driven. Properly setup the KZ twins have a similar amount of vibration when compared to their larger counterparts. In theory they are achieving the same balance as an inline 4 - where an inline 4 offsets the center two cylinders 180 degrees to for secondary imbalance the twins use a mechanical balancer to do the same thing.
What is cool about these twins is the engines spin the opposite direction of the wheels, counteracting the gyro - same as Moto GP. Jack-up the rear end to decrease trail, tune the suspension a bit, and these bikes can be surprisingly nimble despite their age and weight.
There could be other things making the vibrations seem worse. Take a look at the rubber bushings holding the handlebar clamps. if these have degraded that could be contributing to the vibrations in the bars. Make sure the engine mount bolts are all tight.
In my experience rubber mounted mirrors, and particularly the foam mounted mirrors, are the biggest culprits in shakey mirrors. I have solid mounted mirrors on a few bikes of various makes and models and they are clear as day, any RPM and any speed.
