Heya pplz, wierdness exteme happening in my motor of late. Here's the scenario, engine cold sounds perfect, no noises knock bumps at all. Once the motor gets slightly below half temp suddenly i start hearing a knock from the motor. I took the valve cover off to mave sure i'm not beating the **** out of the lobes on the vavles however visually there's no signs of hard wear on them @ all. Replaced the CCT last summer and just for comparisson sake i took off the cover where u can see the cam chain on the botton and compared the extension of the old to the new CCT and it appears i have about 1/4 inch left for how far out the CCT shaft extends on the new one so i don't think it's that. I've tried already running the highest octane i can find @ the pump through a full tank and can't figure this out. The problem continues to haunt me. Changed out the oil last week and topped it up with 10w40 but that didn't seem to do a thing. I'm near wits end here and ready to goto a shop but don't wanna get taken to the cleaners on her (ie. i need to walk in and basically ask to have them check & do the following...). The only oddity i saw was while checking the spark plugs, cylinder number 3's plug appears a little bit more black arround the ceramic then the rest. Any idead / comments / suggestion?

 

I think you on the right track with it being a detonation knock, sometimes the coils can be at fault (once they get hot) or it could be the lead itself to no: 3 cylinder. a big end noise is a big end noise (& its usually pretty obvious) or it could just be a ****ty plug. good luck

 

heidegger, have you tried having the carbs balanced. When Honda first brought these bikes out they used to knock a lot and new customers were taking them back to the dealers but it was found to be a characteristic of the bike, however as i say on revs and once warm the CBR can knock a little. Usually around the 3grand mark then it calms down. This is mainly due to the carbs needing balancing. Also have you checked the fuel pump? Start the bike without the fuel tap turned on, is the knocking sound the same? If so could be the fuel pump on its way out. I have obviously hever started the bike without first turning the fuel tap on. hahahahaha

Other than that no suggestions.