Matty Posted June 16, 2022 Share Posted June 16, 2022 77000km on the bike. Rattle has gotten worse over the last 3000km while I waited for cam chains to arrive. While free revving, it is present between 3-4000rpm. On the road it is present from 3000rpm through the rev range with steady throttle and when backing off and cruising. I don't notice it when on WOT. The sound is more present from the rear barrel up with a stethoscope. No noise at idle. New cam chains and tensioners made no difference. I have also tried manual tensioners with no change. Guides look ok with very little wear. Any suggestions before I have another look for a possible crack in a guide I missed before or a sticking bucket? VFR Rattle.mp4 Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted June 16, 2022 Member Contributer Share Posted June 16, 2022 Are you sure that is inside? Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted June 16, 2022 Member Contributer Share Posted June 16, 2022 More troubleshoot is in order before you buy any more parts... the noise in time with the crankshaft... possible source of crankshaft speed noises are a scuffed piston and stuck piston ring... damaged rod bearings... To help pin point the exact location of the noise hold a long tip screw driver or a length of garden hose up to your ear and probe the suspected area... A skuffed piston will bind the ring from expanding in the bore resulting in low compression and a rattle noise... To pin point which cylinder might have a skuffed piston take a compression test... focus on the weak one... To check for a bad rod bearing set the engine at high idle and remove one spark plug wire at a time... if the noise stops then that's the cylinder with the bad rod... if noise continues after both spark plug wires were removed then the noise is something other than a rod knock because a rod will not produce a knock by just turning over the piston... it takes the spark of combustion to produce a sharp metallic sound... Link to comment Share on other sites More sharing options...
Matty Posted June 21, 2022 Author Share Posted June 21, 2022 No change in noise with coil sticks unplugged one at a time. With a stethoscope, I can hear the noise more from the rear cylinders but I could not notice a difference between the left and right. A compression test delivered 95-97psi across the board, which is not within spec but a close range. It might be worth taking some more parts off to have a better look. I think you might be on the right page BusyLittleShop, I might be hearing some piston slap. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted June 21, 2022 Member Contributer Share Posted June 21, 2022 Have heard worse than that. Is there any chance of excessive valve clearances on one or two valves? Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted June 21, 2022 Member Contributer Share Posted June 21, 2022 1 hour ago, Matty said: No change in noise with coil sticks unplugged one at a time. With a stethoscope, I can hear the noise more from the rear cylinders but I could not notice a difference between the left and right. A compression test delivered 95-97psi across the board, which is not within spec but a close range. It might be worth taking some more parts off to have a better look. I think you might be on the right page BusyLittleShop, I might be hearing some piston slap. I read recently that compression readings will be low if the adaptor doesn't fit fully into the spark plug hole; the extra air volume reduces the compression ration. Just a thought. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted June 21, 2022 Member Contributer Share Posted June 21, 2022 Plus you need throttle wide open when doing compression test ! Sounds like cam chain or tappet noise to me, but if you replaced the chains & tensioners not likely to be that. Have you checked the Vtec valve clearance ? Link to comment Share on other sites More sharing options...
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