I just performed a valve clearance adjustment on a 2002 CBR 600 F4i. They weren't that bad out of spec...had to replace 5 shims. After adjustment, with the cams in and torqued to spec, the clearances are all within spec (.008"+-.001" for intake and .011"+-.001" for exhaust). I checked the timing many times and in addition to that, I marked the chain and cam sprockets before taking them out to make sure I got them back in the same way they came out.

After starting up the bike, it warmed up normally, but after the rpm fell back down to normal idle speed, when you blip or rev the engine, I hear a loud knocking or hammering sound. This bike has already had the CCT replaced once and besides that it doesn't sound like rattling or "bb's rolling around", it is a consistent knocking that speeds up and gets louder with engine rpm.

I know that I took great care to make sure the timing is correct; I didn't feel any abnormal resistance when turning the crank by hand before cranking it; and compression seems good (didn't measure, just seems good); and again, it didn't make the noise until after the choke/enricher turned off....so I really don't think it is a piston hitting a valve.

Could it be a valve sticking? Carbon buildup? Debris stuck in a valve? Engine oil not getting up in the head? Any other ideas before I tear it all back down again?

Thanks!

 

I hate to say it but you might want to get back in there and double check the torque of the cam shaft retainers.

Even beyond that, I'd go back in and loosen everything and retighten using the specified "star pattern"....starting in the center...and using two torque values. One to snug everything then one to set recommended torque values.

Just my .02

 

thanks bergs

I just found that the manual says to put oil on the cam holder bolts...but I didn't do that...I did torque them to 9ftlbs in the pattern specified in the manual...perhaps since I didn't put oil on them first, they didn't get torqued enough...and that is causing the cams to knock around.

I guess I'm going back in...

 

so I decided to try pouring some ATF down the throttlebodies first to eliminate it being a sticky valve before I pulled the cams again....and it fixed it...I guess I could have knocked loose some carbon buildup or something when removing and reinstalling the throttlebodies. In any case...it's fixed.