Oops! Forgot the idler roller

In case you're ever wondering, if you forget to install the cam chain idler roller that goes between the block and the cylinders - it is possible to raise the cylinders about 2" without exposing the piston rings (which would be another dilemma). Then you can carefully install the roller, axle, and rubber blocks, push the cylinders back down and the problem is solved.
Don't ask me how I know, haha.
Unfortunately I didn't stop to take any photos during the "operation"

happened to me on the last z1 build, but caught it before I used the block down completely. Problem is the shaft has to go under the base gasket creating a slight problem but I got it.

Yeah, I was lucky too. I noticed it before the head went back on. Noticed the new roller in a bag when looking for something else!  

Guys, you're in good company there: I once mounted the cylinder head after installing only one guide pulley at the front and one at the back! Mind you, for the rear pulley, I forgot the lower part of the chain tensioner... oops!  - Sometimes your mind is already a step ahead...As long as we noticed our errors and faults, we can fix it and it didn´t result in  a crash!
We are all only human, therefore we make mistakes, errors and nonsense. Nobody is perfect!!!