bike down on power and sound like a v twin (running rough)

[m-lynch07]

Hi. I have a 2003 honda cbr 600 rr. I recently overfilled the oil and it backpressured into the airbox. After having someone clean it, clean the spark plugs and run throttle body cleaner through it, it now runs. Problem is it feels like it's a 250. Really down on power and sound like a v twin instead of a v4. Runs rough.......any ideas. I've been told possible head gasket or something

[Rik398]

Head gasket would probably mean smoking, and milky looking oil.

If it sounds like a twin, it could be running on 3 instead of 4 cylinders or something. After its been running for a while, see if all the down pipes are of similar temperature. Spray water on or something. If one of them is cold, it aint working. Check all the spark plugs are functioning and that the leads are secure on top of them. Thats what I would start with.

[m-lynch07]

Yes I figured out it was runners on 3 cylinders after it was running again. I believe dirty spark plug is making it not fire.

[nikolees]

some years ago I was driving my dad's Alfa Romeo 75 and at some point the engine sound like a helicopter...

turned out that one of the spark plugs had been out of place, I put it back on and everything was ok..