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[Starquest]

You can see the video on YouTube under Yamaha fj 1200 clunk noise. I can't downloaded here, sorry.

[Paul.1478]

this is the link if anyone wants to listen.

https://www.youtube.com/watch?v=2zJaJFVvim0

[Starquest]

Thanks,Paul. I'm not very good with this staff.

[RPM - Robert]

That sounds like it popping through the carbs. Do you still have the airbox installed?

That would explain the muffled sound of the popping/backfire

That can be a result of the cam timing being off and/or the carbs are lean at that held throttle position without any load on the engine.

[Starquest]

No. Dual uni pods. It's a metallic sound coming from the Franck. May be starter chain?

[Old Rider]

I have some wild guessings: if the carbs not syncronized the clutch can make a clunking sound  or  it can be the starterchain hitting the oiljetnozzle
or it can be the jackshaft hitting into  side of crankcase  or  it can be the rear camchain rail jumping up and down because of a veak spring  on the bolt holding it in place  or it can be as simple as a lose exhaustbend .

[Old Rider]

After hearing the sound again I'm thinking maybe the cam chain tensioner has gone bad or maybe it sits upside down.
Try to use a long screwdriver and hold it to into your ear and listen.

[Starquest]

Sorry. I was busy this week. When I checked the valve lash last time, the timing chain looked ok, despite the cam timing being off. I checked the carbs sync this week. Robert did it a good job bench sync the carbs. May be I try 42.5 pilots first. If that’s not solving the problem, I will mess with the cam timing.