rear Cylinders not firing

Hi Guys big problem here, I left my bike sitting for two month and now it start badly and run rough. I just found the engine rear cylinder are not working as i put an hand on the rear headers and both are cold. Before this I had change the coolant, but i don't think this is the problem...I found somewhere the FPR fuel pressure regulator can be involved and this morning I remove the airbox to check it but it seems OK no leaks. I also check before for the sparks and both are working. Is this related to the ECU maybe? I'm a little frustrated as the bike run flawless before I store it two month ago...any ideas?
best regards

 

What is the state of your Battery? Was it charged while in storage? Low battery voltage and poor battery capacity can cause strange issues!
- FPR leakage will only effect cylinders 3 and 4 not cylinder 1.
What do the Spark Plugs for 1 and 3 look like? Are they wet, meaning the injectors are working? Check if the injectors are firing.
Perhaps the Spark Plugs may be fouled or just need replacing? Try Iridiums - NGK CR9EHIX-9's
Do you have any Fi Fault codes displayed with the Sidestand Down?
What is your Fuel quality like? Could you have bad fuel, condensation maybe?

Good Luck.

 

Hi thanks for the reply, I checked the spark plugs and the one in cylinder 1 is clean while cylinder 3 is black and fouled, I also check if they work and they do sparks. I wouldn't want to have damaged the control unit when I reattached the battery as I know the ECU is divided from rear and front engine cylinders. I don't have any FI fault codes, does a damaged ecu can throw this?

 

If you replaced the battery with your Ignition Switch to OFF then you can't damage the ECM because power to it is isolated by the Engine Stop Relay..
" ECU is divided from rear and front engine cylinders" ! I haven't heard that before, what do you mean by this?