Odd sound at start-up

[rcannon409]

Guys, I searched for this, btu could not even think of a decent way to do so.

I climb on bike.....KPSS initializes and fuel pump starts. Seconds later things are quiet so I hit the started.  Just as the bike starts, I hear an odd engine noise. It lasts a split second, then goes away.  Not grinding, nto quite clicking, but a sort of combination of both.

I'm wondering...is it the cam chain tensioner ?  When full pressure is reached, it quiets down? 

Question, please. Is there any need to do anything about this?

 

[C1xRider]

Yep, it's the timing chain rattling against the side of the engine case until oil pressure builds up and tightens the chain tensioner.  If it bugs you, just don't start it when it's on the side stand.  Instead, stand the bike straight up and down, and it should cure it.

 

[jimp]

If it bugs you, just don't start it when it's on the side stand.  Instead, stand the bike straight up and down, and it should cure it.

I claim that's an urban myth. Or is that a Kipass myth? 

My '08's done it since new, no matter whether it's upright, leaning left, or leaning right. Once the oil drains down, leaning or not has no effect.

How come other manufacturers VVT doesn't do this?  >

 

[rdm197apd]

??? I've always wondered what that noise was. I added a quart of Lucas during a previous oil change and it cleared up for a bit. with my current oil change, i added the quart (substituting for one quart oil) and the rattle is still there. it does seem to be a little quieter when on the center stand, but not much. 

 

[rcannon409]

Thank you for the responses. Sounds like a  non issue.  I switched to Rotella synthetic just as I crossed the 5k mile point and the sound is less, but still there.

 

[C1xRider]

Mine barely does it when it's on the side stand, and not at all when it's upright.  Not a myth.

The timing chain tensioner has a ratchet mechanism that will prevent it from retracting too far when there's no oil pressure.  Depending on how loose your particular chain is in relation to how far from the current tooth of the ratchet mechanism your tensioner is on, will dictate how much rattling noise your bike will make.

As the chain stretches and the tensioner slide wears, the ratchet mechanism may tighten to the next tooth, causing the rattle to all but go away, at least until things wear and stretch a little more.

The auto-adjusting mechanism can be replaced with an old style manual adjust tensioner (aftermarket I think), if you want it to always be snug and not rattle.  That would also require you to make adjusting it part of a regular maintenance schedule though.

 

[B.D.F.]

The 'start up rattle' is caused by the slightly loose cam chain rattling against the engine case. A lot of C-14's do this but only when started on the side stand.

I looked into this a few years ago and found the problem is caused by the automatic cam chain tensioner having a lot (too much perhaps) travel in it between the extended position with oil pressure and the extended position being pushed back to the mechanical stop, before there is sufficient oil pressure to again fully extend the tensioner. I am speaking here of extended or pushed back being between any of the mechanical stops along the travel of the tensioner itself. In other words, the tensioner can retract just far enough to sufficiently loosen the cam chain so it slaps the engine case until it is full of oil under pressure.

Extended it looks like this:

When the engine is started, the tensioner can retract until the circlip stops it and it is a fairly long way (about 3/16" measured):

The easiest thing to do is just ignore the noise- it will not cause any problems. I changed my tensioner over to a manual type and got rid of the start- up rattle but have to <very occasionally> adjust the cam chain tensioner now. It is fast and easy to do but the right / mid fairing must be removed to get at it. It looks like this:

Brian

Guys, I searched for this, btu could not even think of a decent way to do so.

I climb on bike.....KPSS initializes and fuel pump starts. Seconds later things are quiet so I hit the started.  Just as the bike starts, I hear an odd engine noise. It lasts a split second, then goes away.  Not grinding, nto quite clicking, but a sort of combination of both.

I'm wondering...is it the cam chain tensioner ?  When full pressure is reached, it quiets down? 

Question, please. Is there any need to do anything about this?

 

[bigpoppa]

Interesting...I've only just started hearing this noise when the bike is cold after switching to full synthetic at my 15k service. I never noticed this noise before when I was running conventional oil (600 & 7500 mile services).

I do notice that I usually only notice it when the bike as load on the engine while it's still somewhat cold. I usually wait until I get 1 bar above the "C" marker before riding off and when I apply throttle, that's when I hear that very light rattling/ticking sounds. After I'm on the road for maybe 15 minutes or so, I don't notice it.

Hopefully it's the same thing everyone's talking about here.

 

[B.D.F.]

The cam chain start up noise caused by a slightly retracted cam chain tensioner only lasts perhaps four or five seconds. Once the CCT is full of oil and pressurized it extends the cam chain will not make any more noise. I think whatever you are hearing is something unrelated.

Brian

Interesting...I've only just started hearing this noise when the bike is cold after switching to full synthetic at my 15k service. I never noticed this noise before when I was running conventional oil (600 & 7500 mile services).

I do notice that I usually only notice it when the bike as load on the engine while it's still somewhat cold. I usually wait until I get 1 bar above the "C" marker before riding off and when I apply throttle, that's when I hear that very light rattling/ticking sounds. After I'm on the road for maybe 15 minutes or so, I don't notice it.

Hopefully it's the same thing everyone's talking about here.

 

[rdm197apd]

I agree with Brian, i believe Big Pappa is having other issues. Maybe the synthetic oil is too thin? After switching to full synthetic in my 350Z, it would disappear. The motor was not blowing any smoke, even under heavy accelleration, and there were no leaks (only had about 38000 miles on it and the motor still looked new), but the oil was disappearing. I checked it one day on a board whim, and discovered it was about 4 quarts low. I guess it was disappearing to the same place all my missing socks go to.