I just picked me up a 94 900RR and I have a buddy that has a 93. I went to his house to compare bikes.

When he starts up his bike, there sounds like there is a knock in the top portion of the engine. When the bike warms up and the idle smooths out it seems to completely go away. He said its the first time he heard it. He said the carbs need some work. . would that have something to do with it?

 

somebody on another forum suggested the 'anti rattle spring'

sounds like its a common problem. Should he get a compression test done?

 

I think you mean the automatic cam chain tensioner. That will give the noise you described with a cold start. The sound will diminish as the engine warms up and oil pressure builds.

 

simple! you need a valve adjustment. fairly easy to do, but if you haven't done it before let your dealer do it.