Bike shop just diagnosed new piston rings required. I put it in because it is still misfiring on cylinder 3 intermittently. Chap suggested that it may not be economically viable to repair. It is a 2001 FZS Fazer, They seem to be going back up in value. Is this guy trying to rip me off?


I had previously dropped the bike off at the same place about three weeks ago but it was running fine then and they tried it through the day and it was fine when I rode it home.


Next time I tried it it was lumpy as shit, stalling at junctions or lights, with a terrible smell of petrol.


Thought it might be sticking carb piston. What would be the symptoms of that? If I started without any throttle either with or without choke it had run fine. Might a start with throttle lift the carb piston before it had chance to lubricate with some fuel. ( or how are these pistons supposed to be lubricated?


Previously I have had the carbs off three times to clean but using carb cleaner and air. Perhaps a clean in an ultrasonic bath is required.


I had done a compression test from cold which gave 14,5 barg for 1,2 and 4 but 12 for 3 but that might have been due to unburnt fuel washing lubrication from the piston rings.


I have swapped over coils and leads to eliminate electrical problems. Spark is healthy.


I have been very busy with work so not had time to sort this out. Also I think I am a bit prone to a reaction from petrol vapours which make me feel ill. Hence I tried the bike shop.




Any one got any ideas/comments?

Hi everyone. I am a new member. I have a cylinder misfire at low revs. Exhaust is stone cold on 3 on tick over. After cleaning the carbs seemed to be the same on starting. I reved up a bit and then went for a run, seemed ok till stopped at lights and when pulling away down to 3 cylinders again.


[size=78%]Spark is good, new plugs, swapped 1 and 2 and 3 and 4 HT leads and swapped the LT connections to the coils, still same so I don't think it is electrical problem. Compression is down 17% on 3 but still 12 Barg. 1,2&4 are 14.5 Barg. I can't remember if I did compression test after warming up by idling so may do a retest after a run. I thought that 12 Barg should still get ignition. All 4 exhausts are hot after a blast on the road. I have had the carbs off twice and cleaned them out with carb cleaner and air. Floats and needle valves al look good but I need to check the fuel levels. I thought it might be the choke plunger so swapped  1 and 3, but no. I also swapped 2 and 3 diaphragms and 3 and 4 pilot jets and pilot screws. I haven't replaced any of the bits.[/size]



I thought that the compression being down might be due to that piston / cylinder being cooler. Put some oil in 3 and rechecked compression but I think I out too much in as it went way up to 18 Barg and oil came out the pressure release valve on the tester. Not checked the valve clearances yet.


No 3 plug does appear to be fouled up a but.


Anyone got any ideas about what this could be?