stuttering fzs 600

[red98]

at last back on my 600 fazer problem.....CRH has helped me out with a long list of possible solutions after quizing a mechanic friend....so my thanks go to both of you  ......top of the list....BENT VALVE.....so ive done another compression test

                                                            cylinder 1...................140 psi
                                                            cylinder 2.....................85 psi
                                                            cylinder 3.....................61 psi
                                                            cylinder 4...................143 psi


these are average figures as i did the test four times,should be about 160/170 psi ,with 40,000 miles on the clock i was not expecting top pressure, within 10% and i would of been happy,the low readings on cyl 2 + 3 has got me thinking  :eek


i then disconnected the plug caps in turn to see what these figures mead in real terms....


                                disconnect plug lead no 1...............little bit flat but idles
                                disconnect plug lead no 2...............flat but wont idle
                                disconnect plug lead no 3...............little bit flat but idles
                                disconnect plug lead no 4...............little bit flat but idles
                                disconnect plug leads 2 + 3............flat but just about idles
                                disconnect plug leads 1 +4.............wont start


so iam now thinking HEAD GASKET blown between cylinders 2 and 3    the bike runs fine between 4/8000rpm so parhaps the pressure of the 2 cylinders is masking the damaged gasket at mid range but at higher rpm the pressure is too great and the stutter returns  ......sounds a bit mad...but could be 
[size=78%]  i might take the head off and have a look,i can check the valves at the same time and regrind the seats to make it worth while [/size]