Excessive vibration 1981 KZ440

Hi allI

I’ve recently acquired a friends project bike a 1982 KZ440 Ltd in a “scrambler” configuration, after a new battery, a carb clean, new carb boots and oil change she starts up great, problem is the bike had an excessive vibration at all rpms; I can’t see what’s in the mirror and can’t feel my hands after a short ride. Previous owner suspected worn big end bearing and main engine bearings. 

 Any insight as to what the cause of this vibration may be?

Video:
youtube.com/shorts/FlK00hCLk40

Do you know if the motor has been apart ? the 440 has counter rotating crank balancers but these have to be "timed" to the crank same as a camshaft, if assembled incorrectly they will throw the crank out of balance !!

Thank you for the insight, I'm not sure if the engine has been opened up. do you know how  one goes about setting the timing for the crank balancer?

jaguar_shark wrote:

Thank you for the insight, I'm not sure if the engine has been opened up. do you know how  one goes about setting the timing for the crank balancer?

Sorry, never been inside one. You would need to refer to a factory service manual

Your vibrating mirror is normal, no need to dive into the engine for no reason.
You can buy/use rubber mirror damper to eleminate this effect.

 
 

You can also try to balance the carbs and check timing & compression

This could not fully solve his problem, it´s a parallel twin engine.
Both pistons are always in the same cranking posision @ TDC and BDC.
It´s a "Good vibration" engine.........

Scirocco wrote:

Your vibrating mirror is normal, no need to dive into the engine for no reason.
You can buy/use rubber mirror damper to eleminate this effect.


 

Whilst I don't disagree I think loosing the feeling in your hands after a short ride would appear excessive - over to the 440 guys, is this normal ?

That is excessive vibration. Something is wrong. These engines are fairly smooth, they are balanced at TDC/BDC by the crank counterweights and secondary imbalance is dealt with via the counterbalance assembly.
 
Bad bearings shouldn’t make it vibrate like that. Bad bearings would manifest as a knocking sound. 

the countershaft balance timing is set when assembling the case halves, similar to setting timing on the cam shafts. You’ll have to get a manual  to check, but if I recall correctly there is a sight window under the oil pan that when the engine is  at TDC a mark will be visible. You should be able to check that the balancer is timed correctly without splitting the cases.  Do you know if your friend had the bottom end open? It’s also possible the balancer chain slider wore down and it jumped a tooth or something but I’ve never heard of that happening 
 

I've heard of guys building customs where they ditch the balancer system and electric start parts.  Something about making the bike lightweight...

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? 

What a beautiful machine, thanks for this advice, the mirrors I purchased came with rubber dampners but alas I cannot see anything.