Mysterious tap/knock/rattle from 99 SV650S

Hi all,

After much neglect of this forum despite being a member for yonks, I'd love some help with an engine issue or suggestions on what it could be.

So the bike is a completely standard 99 SV650S, was my commuter for a little while and sorta stopped using it a bit, although its always had regular runs (at least twice a week) Cosmetically the bike is rough but I've always looked after the mechanicals! 37 thou on the clock. Having said all that I'm partial to a wheelie every now and then if that could be causing the issue! (on a private road, etc, etc)

So during a ride home from work last week the bike developed a tap/knock from what sounded like the front of the engine, between 3k RPM and maybe 5.5k. However I can only really hear it with earplugs in, and whilst the bike is being ridden, so very hard to demonstrate to a mechanic!

the sound is almost like an exhaust blow, although I've already checked that its sealed by placing my hand over the end of the exhaust and the bike dutifully cuts out under the back pressure. The tapping increases in frequency the faster the engine revs between 3 and 5 thou, before disapearing around 6.

The bike has done about two thousand miles since the last oil change, so hopefully that's not the issue. Currently the ideas from the local garages are terminal, one saying the cam chains have failed, the other suggesting that the bottom end bearings are shot. I personally would have thought the mysterious noises would be much louder if it was the case that either of those was going (Bearing in mind you can't hear this tapping to the naked ear!)

Any ideas on what this could possibly be other than being terminal?

TL;DR SV650S tapping noise between 3k and 5k RPM, any ideas

Appreciate the help, in advance!

[Fen Tiger]

Loose ear plug?

[DJ123]

Does it make the noise when the bike is accelerating or decelerating Or only on a constant throttle?

[Craig380]

Camchain tensioner? My understanding is the CCTs on the early bikes was a bit dodgy and prone to sticking, allowing the chain to rattle. How does the bike sound at tickover?

[maviczap]

cct or failing tensioner blade?

[Fen Tiger]

Are you sure the noise is coming from the motor? Maybe something rattling in the faring or under the tank. Even a loose front mudguard can produce motor speed dependant noises.

Thanks for the input guys.

The bike has always had a bit of cam chain rattle at idle, although this hadn't really changed over the past 11k miles.

It's only happening on a constant or accelerating throttle.

Maybe CCT's should be the first port of call?

[maviczap]

Yes, worth investigating before assuming its the bottom end.

Sv engines are generally good, unless abused.

How long are these wheelies? If anymore than 3 seconds or so on a regular basis, i'd suspect oil starvation. If you only do little bunny hops, straight up and down, I doubt thats the cause.