klipsedeville Posted April 14, 2022 Share Posted April 14, 2022 I have just replaced the entire front top cylinder on my 6th gen 2002. This was because I had a bent valve on the intake of #2 cylinder. The whole problem started when I heard the infamous clatter from the front CCT. So I rebuilt it twice now but unfortunately, I rode out on a wet day and less than 3 miles the bike stalled out and won't turn over. Opened up the valve cover and found the bent valve, infact, the intake camshaft was dislodged, and 2 out of the 3 bearing journals were scuffed and scratched badly, so I just replaced the top with a good used one. Bike starts up and runs fine until you rev up the rpm. There is a very loud rattle/clatter coming from around the chain tensioner. The sound is consistent with engine rpm, so I installed manual tensioners since the OEM had already been rebuilt twice. Still the terrible rattle and clatter. It is constant and consistent with rpm. I have not ridden the bike since the new cylinder top was put in. After digging around, I found that the you can feel the metal clatter right off the manual tensioner. Infact, if you loosen the tensioner enough, you will see it moving up and down each time the clatter/tapping happens. So I am wondering, could the chain have been damaged or has the guide worn so bad it has developed a point where each chain link catches/hits while rotating? I will try and make an audio of the sound and probably a video. Can anyone guide me on how to remove, inspect and replace the cam chain guide and chain? I do not know where to start from? Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 14, 2022 Member Contributer Share Posted April 14, 2022 The photo below is a VTEC cutaway which might help you visualize things going on inside. A video of it running and the the movement in the tensioner you describe might be helpful. If as you say the camshaft was "dislodged", something catastrophic must have happened. A bent valve usually means that either that it was stuck and was bent by the force of the cam pushing on it, or the cam timing was or became off and the valve contacted the piston. There's a youtube video with a earlier VFR cutaway, and the clearances are very tight, demanding spot on cam timing for it to avoid catastrophe. Before replacing anything, I would want to know what caused the bent valve in the 1st place. Without knowing that you might be chasing symptoms vs solving a problem. If the valve did contact the piston, you would surely have noted that when the head was off. If that's the case, it's time for a replacement motor vs trying to rehab the one you have. You can go to the downloads section here and for free download the VTEC service manual which will provide you with the procedure to remove / replace the cam chains and guides. Link to comment Share on other sites More sharing options...
Member Contributer ShipFixer Posted April 15, 2022 Member Contributer Share Posted April 15, 2022 This thread is already 😬. Yikes! Quote The sound is consistent with engine rpm, so I installed manual tensioners since the OEM had already been rebuilt twice. If you poke around with Google and look at the really old threads here, you'll find that rewinding the tensioners is never successful. Nor were tricks like opening up the oil port. No way out of just buying a new one. If I recall correctly, the new part number is also the 8th gen part number and those are stouter. Hence why all the threads are pretty old. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted April 15, 2022 Member Contributer Share Posted April 15, 2022 Agree with ShipFixer. A CCT "rebuild" would mean a new spring fitted, not just retensioning the old plunger spring! Always best to just fit a new one. Also those manually adjusted ones are bad news. Theres a fine line between a correct, under or overtensioned cam chain. The OEM will take up any stretch or tensioner wear, not so the manual version. Can only suggest going through the service manual. The bent valve, what has this done to the valve guide, and piston? Good luck, hope you get it all sorted. Link to comment Share on other sites More sharing options...
klipsedeville Posted April 15, 2022 Author Share Posted April 15, 2022 8 hours ago, Cogswell said: The photo below is a VTEC cutaway which might help you visualize things going on inside. A video of it running and the the movement in the tensioner you describe might be helpful. If as you say the camshaft was "dislodged", something catastrophic must have happened. A bent valve usually means that either that it was stuck and was bent by the force of the cam pushing on it, or the cam timing was or became off and the valve contacted the piston. There's a youtube video with a earlier VFR cutaway, and the clearances are very tight, demanding spot on cam timing for it to avoid catastrophe. Before replacing anything, I would want to know what caused the bent valve in the 1st place. Without knowing that you might be chasing symptoms vs solving a problem. If the valve did contact the piston, you would surely have noted that when the head was off. If that's the case, it's time for a replacement motor vs trying to rehab the one you have. You can go to the downloads section here and for free download the VTEC service manual which will provide you with the procedure to remove / replace the cam chains and guides. Thanks. Well I am not sure if the valve contacted the piston but I did inspect the piston and no signs of damage. My guess on the cause of the bent valve maybe the failed cct after rewinding and the camshaft bearing journals that were worn and scratched increased free play causing the timing to skip. However, I have put in a good cylinder head and the timing is spot on now, revs up to 9K RPM without any issues. I just want to get rid of the clatter coming from the chain tensioner. See more pictures. Link to comment Share on other sites More sharing options...
klipsedeville Posted April 15, 2022 Author Share Posted April 15, 2022 44 minutes ago, Grum said: Agree with ShipFixer. A CCT "rebuild" would mean a new spring fitted, not just retensioning the old plunger spring! Always best to just fit a new one. Also those manually adjusted ones are bad news. Theres a fine line between a correct, under or overtensioned cam chain. The OEM will take up any stretch or tensioner wear, not so the manual version. Can only suggest going through the service manual. The bent valve, what has this done to the valve guide, and piston? Good luck, hope you get it all sorted. I agree with both of you. I already have the OEM parts ordered. Waiting. I only put in the manual ones so I could complete the job of replacing the cylinder head. Will take a closer look at the manual. But if anyone has done this job, pointers would be of help please. Looking at it, I may have to remove the starter clutch assembly and that can mess with the timing and I don't want to mess with the rear cylinders at all. There a way to retain the timing? Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted April 15, 2022 Member Contributer Share Posted April 15, 2022 Those cam bearings were really roached. That's very unusual - even high mileage engines don't see that. Could it have been lack of lubrication? Agreed with new CCTs. "Rebuilding" them is just over stretching an already fatigued spring - new ones are the way to go. Hence why many of us live our gear driven cam motors! Best with it. Link to comment Share on other sites More sharing options...
klipsedeville Posted June 22, 2022 Author Share Posted June 22, 2022 Sorry, been caught up with other life challenges. Here's an update so far. I have swapped three more cylinders even got a friend to agree to pull his from his running bike and still the noise persists. Things I've done: swap cylinder heads, new timing chain, new ccts, flushed oil, changed chain guides. Still no luck. Could this be from the crankshaft? Maybe worn bearings? Or am I not getting the timing spot on and the valve is touching the pistons? I've attached audio recording of the sound.Vfr-2.aacVfr-1.aac Link to comment Share on other sites More sharing options...
klipsedeville Posted July 25, 2022 Author Share Posted July 25, 2022 Just an update so far. After so many hair pulling attempts to fix the tapping sound. With the help of a mechanical stethoscope, I was able to trace the noise. It was coming from #4 piston! Removed the top cylinder and ah ha! The piston has a lot of up/down play. At TDC and BDC, if you tap the piston head, it falls lower with a thud sound. Piston pin worn so bad. Explains why the noise was coming from the top right side of the engine. All bearings look ok, but I'd be replacing them all. Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted July 25, 2022 Member Contributer Share Posted July 25, 2022 THAT is some dedication! Nice work. Link to comment Share on other sites More sharing options...
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