k75 running rich

I did not have any experience with the K series until a friend of mine asked me to sort out his K75 that was running very rich. When you blip the throttle thick black smoke comes out of the exhaust, and if you open the throttle very fast it tends to stall. I have done some reading on the matter and checked the following

injector resistance OK
cleaned injectors and checked injector spray and flow
ground connection if injectors OK
communication between injectors and jetronic OK
TPS OK
comm TPS-Jetronic OK
balanced the throttle bodies bypass screws
fuel pressure OK
crankcase breather tube fixed (was torn)
cleaned the air flow meter potentiometer and its ''door'' it seems to move freely
Changed battery
air filter OK

Nothing worked, i am back at the beginning. The thing is that as i have read the air flow meter and the Jetronic are considered to be bulletproof. So if they are not the source of the problem what else could it be? Unfortunately i dont have a second bike handy to check its Jetronic and MAF meter.

i would very much appreciate any help on this

forgot to mention it...

checked that too

by the way that sensor could cause problem only when the motor is hot. In my case the bike runs rich when cold or hot also

Hi.
Check for intake air leaks between flow sensor and engine intake ports.
Is it possible to see aif flow meter "door" while engine running? Does it move when throttle operated?

I'm afraid that you need another healthy bike to swap parts (Jetronic, MAF, etc)

Klaus, you are right

Zitat

Air leaks between flow sonsor and motor block will not enrich mixture. Due to underpressure leaks will allow air to enter the system, making the mixture lean.

But anyway it can lead to misfiring or abnormal fuel preparation. I think that this must be checked also, just in case