engine knock

This is my first question for the forum, I just finished my introduction post a few minutes ago.
My VFR does have an issue I'd like to ask about though. This is how it went:
We were on a trip from Ohio to Kentucky. It's a fast group, and the bike was getting run pretty hard. I'm a licensed roadracer so I do like to run hard. But after we'd stop and I'd shut the bike off for say 15 or 20 minutes, when I'd start it back up I would hear a knock in the engine as it would sit idling. We'd take off start riding and at every stop sign and red light I'd listen down to my engine.....knock was always then gone. But then the next time I'd shut it off and start it back up, the knock would re-appear but then go away.
Does anyone have any idea what might be going on here? I bought this bike with 1900 miles, it is mint condition and runs great, but this knock concerns me. It's not a loud knock....if you're 10 feet away you're not gonna hear it, but sitting on the bike with my helmet on I hear it clearly. And it doesn't even do it every time I start it up, it's pretty intermittent, but it's there.
Oil level is good and oil was just changed before I bought it. Only thing I can think is maybe they used the wrong viscosity or something....I don't know.

 

The VFR calls for 10 w 30 oil now, a bit light IMO, maybe thats what is in it and because you are thrashing it a bit, it gets a bit noisy.
You could try dropping the oil and putting in a decent 10 w 40 and see what happens then.
just a suggestion.

 

That's exactly what I did yesterday. The manual states to use 10W30 or 10W40 either one, so I bought some Pro Honda GN4 and a new filter and changed it. Same result.
Knock comes and goes as it pleases. Man this has got me stressed. I don't know what to do. I can have 20 people listen to this noise but no one is gonna know anything until they take it apart and inspect it. But at the same time I'm half afraid to ride it because what if this knock manifests into a break-down on the road? I don't wanna look like a Harley Davidson rider along the freeway!
I'm a little suspicious that the guy who sold it to me knew about this....possibly.....just my initial thought. Wish I knew if a way to have this VIN checked to see if it had ever been to a Honda dealer in Pittsburgh for this concern.
But at 1900 miles what could possibly be wrong with it? I can't believe it's got any kind of serious problem, even despite the noise I'm hearing.

 

Are you running a premium fuel? I always run 98 RON
I seriously doubt that there is anything seriously wrong with the motor, but you could try running a stethascope over it to try to determine the source, but a possibility could be the front cam chain tensioner, but thats not a heavy knock, more a rattle.
These motors are fairly good, anything serious is unlikely IMO.
If it was anything serious, the knock wouldnt go away.

 

What do you have the idle set at?

 

Idle is at about 1100 which is in spec. But it seems to kinda vary, sometimes smooth sometimes a little rough. Also doesn't seem to idle up in the morning like it should anymore. It did this real nice when I went to test ride the bike, but since the trip it doesn't.
Today it's really knocking, I mean it's loud. Rode all the way to Medina from my place and it was fine, got it home and it was really raising heck.
It exhibits most of the symptoms of injectors that are out of sync. It's got a lean surge very noticeable between 3000 and 5000 RPM, and like I say the idle is kinda erratic. For $158 plus tax I can have the injectors synced. I may just do it. Might be all it needs.

 

Set the idle to about 1400

 

I personally am not gonna adjust anything. It's going to the shop next Monday. This thread didn't really yield anything to make me think there's any other option. They say it is either a fueling issue of some kind (i.e. clogged injector, injector sync, etc) or a malfunctioning cam chain tensioner, which they have seen one time.
I'd like to understand if injector synchronization is the same as a throttle body sync. Does anybody know if this is one and the same or is it 2 separate procedures?

 

AFAIK the injectors are electronic and controlled by the ECU

 

One thing I have determined it's that it's top end. The noise is definitely at camshaft speed.

 

I bought a used 07 with very low miles and determined the dealer only started the bike enough to move it out for display and then in at night. It was not enough to get the engine up to temperature and I had 1 fouled spark plug thus a deal cylinder. Engine had what you could describe as a knock and definitely a rough idle. Nothing replaces someone there in person to diagnose a problem, but this was one of my personal experiences.

 

So it was essentially a fouled plug that caused the knock and rough idle? I've considered pulling the plugs and looking at them, but then I think "nah....that couldn't have anything to do with it"..... But maybe it could.....

 

Every once in a while (like last Friday) I get a knock but that's just my flapper valve. Do a search on the flapper valve cause that just might be your issue.

 

my 99vfr was doing the same thing and I figured out it was the flapper valve ..

 

On this bike it has nothing to do with the flapper valve, of that I am sure. I know the sounds the flapper makes, and this isn't even close.
And it's not a bad or fouled plug, because I checked all 4 and they are perfect.
Noticed a little bit of backfiring through the airbox.
Bike is at the dealer now, waiting for their opinion on what is wrong.....

 

I was gonna suggest Checking the cam chain tensioners because i had a knock aswell and i turned out that i switch the type of oil i was using and the knock started. Switched back to the original oil i was using and knock is gone. FYI oil i switched to was Motul 5100 10w40 and original oil was Castrol 4 stroke motorcycle 10w40. Keep us updated on what the dealer thinks!

 

Well, the bike is back, and untouched. The dealer was unable to duplicate the problem sufficiently enough to diagnose it. Yes they heard it, but not long enough at a time to figure out what it is. So I took the bike, I'm gonna run it and whatever happens, happens. If a bigger problem manifests then GOOD!!! At least then we'll know what to fix.
They're positive it's not a throttle body synchronization problem, and we've ruled out cam chain tensioner problems.
I'm just gonna run the snot out of it, as I do most of my bikes. My Kawasakis and the Suzuki don't complain, we'll see what this thing does. Don't probably need to tell any of you that this REALLY disappoints me in this bike.

 

My money says it's a CCT issue, well documented problem with these engines. I'm pretty dissapointed too, I'm currently waiting on my APE tensioners to arrive so I can take care of the problem once and for all, sick of the damn woodpecker gremlin in my engine comin and goin as he pleases