New Member and Knocking Question

Hi to all,

I have been a member of the Forum for a few months now, but haven't posted until now. I have been riding my SV650 K3 since the end of august when I passed my DAS, ive covered about 1300 miles already (two trips from London to York and several weekend voyages down to the beach making the most of the weather as well as commuting to work and back daily)

While riding I have noticed what I can only describe as a knock as the bike revs between 3000 and 4000 RPM, it does it along the rev range in both directions, when reving through the range during acceleration and when rolling off/clutch in. It is only a single brief knock, only just noticeable above the standard engine noise with a standard exhaust at slow rates of acceleration.

Is this a common noise? If it isn't could someone please help me with the diagnosis? My engine isn't about to spit a piston out of the head is it

Thanks

Chris

[rictus01]

Greetings, the use of the word "knock" is normally in reference to bottom end, but doesn't run consistent with what you discribe, so it's probably a terminology thing, have you tried to replicate the noise statically ? where on the bike does it sound like it's coming from? left/right side? back/front? drivetrain/engine?

odd noises are difficult to acccurately diagnose without actually hearing them (although that doesn't stop some using the "wild guess" method), if you're not to sure, get someone local to have a listen.

Cheers Mark.

[Biker Biggles]

Probably nothing to do with it but check your oil-------frequently.

Thats just a general comment.Is your chain well adjusted?

I would make sure the chain is well lubed, and adjusted as previously mentioned. At least you can kind of rule this out for not a lot of money. Mine makes not-nice noises unless I look after it. Also what milage is it ? Have the valve shims been checked lately?

I've spent both commutes to work and back trying to locate the noise. I have narrowed it down to the engine, but i'm not sure which cylinder, also the noise is more predominant from the right had side of the bike. The noise is still made statically. One thing i have noticed is looking through to the cylinder head, their is a cylinder which has two linkages, one is the throttle linkage (when the bike is not running it still moves with the throttle) the second i am unsure of as it does not move when the bike is off, but when it is on it moves. The second linkage doesn't have a smooth motion, when throttle on/off it seems like it has a bit of a delay/lag and judders before becoming smooth with the throttle linkage. What is this linkage for and could this be the route of the problem?

Oil was replaced less than 500 miles ago, chain was lubed and tightened at the same time so shouldn't be that although it is my first bike and i am used to working on cars, i could have been a complete plonker and overtightened the chain, but im told about an inch of slack is what i should have.

The shims are what i'm hoping it isn't, the bikes on 20,000 miles and I have a full service history, a service was carried out at 18000 miles, but im not sure if the shims were checked then or not, i mite have to dig through the paperwork to see if theirs more information on that.

Thanks for the helpful tips so far.

Hi Chris,
If the noise is being made whilst bike is stationary and in neutral it`s most likely engine related. Try a stethoscope up against each cylinder, then cylinder-heads then bottom of engine (crank). As mentioned a knock normally relates to worn crank bearings but could also be small ends, conrod etc. It wont be valve clearances, they tighten up and quieten up with wear.
cheers,
chris

Neat idea, thanks for the tip i will get myself a stethoscope and see if i can narrow down the problem.

If the knock was due to bottom end wear, (I don't think it is as the noise was distinctly louder towards the top of the engine, it was most distinctly heard when I stuck my ear against the opening in the chassis between the cylinder heads.) wouldn't the knock be repetitive? rather than just one knock as you go through 3000 to 4000 rpm? if i maintain the revs above 4000 then the knock doesnt persist... Its a genuine mystery!?!

What sort of mileage has your bike done? To me it sounds like the CCT (Cam chain tensioner) has gone, this will normally happen on a bike at around 30k miles (maybe a bit more for a reliable twin like the SV). If you are mechanicly minded you can change this yourself, but its not the easiest job, as you have to set it up correctly after. Unfortunately its quite an expensive thing from a dealer, due to the man hours .

Bike has covered 20000 miles, i shouldn't have a problem doing it myself if it is this. Gives me something to do over a weekend anyway

[yorkie_chris]

That linkage sounds like the secondary throttle valve linkage.

On the other side there is a servo which controls it.