Carbon on the valves

[Slyder]

So I've got the bike in pieces scattered about and for some reason I decided I wanted to look down the TB's at the valves. Cracked the secondary flies open and then the primaries to see some nice carbon built up on the valves. Here's the strange part, on the #1 cylinder, the left valve has carbon on it. The right valve is clean, no visible carbon at all. The #4 cylinder is almost like that, one dirty and the other mostly clean. Of course the right valve in the #1 cylinder is close to cylinder #2 (hotter)...but #2 and 3, valves are full of carbon.

Any idea why that is? Is that by chance an indication some shims need to be changed?

[Danz19899]

only thing i could think of is either the throttle bodies aren't synced or the fuel injector is a little carboned up.

[butcher bergs]

Could be the FI is programmed to send more fuel to the middle cylinders hence the carbon buildup.....and no, nothing to do with shims. Check valve clearance for that.

[Slyder]

I know it's oh, about 3500 miles past due for a valve check, the upper end is all greek to me so I wondered if a worn shim might cause a valve to not open / close fully.

I really need to get the valves checked and have the TB's synch'd.

I thought it was strange that the valves in the same cylinder looked night and day different.

[butcher bergs]

...the upper end is all greek to me so I wondered if a worn shim might cause a valve to not open / close fully.

It will however now you are talking about severe damage to other valve train components besides the shim or perhaps a valve clearance that was set so grossly out of spec that you'd likely have power issues or possibly piston-to-valve contact.

[scubasteveRR]

I just had my valve clearences checked and I had carbon build up on the valves as well. my bike was running rich though becasue my airfilter was nasty and not letting in the air it should have.

How does your air filter look? While you have it apart clean them by using "top end cleaner" (i believe thats what they used) and spraying it in there and let it sit to loosen up the carbon.

[scubasteve]

Fueling for individual cylinders will never be exact - the inner cylinders, if the ECM is capable, are definately fueled more rich than the outers to help prevent detonation and such from them running hotter. I would do a seafoam treatment on it, then replace the spark plugs and call it a day.

[Slyder]

Air filter was dirty, but not what I would call nasty.

The plugs however came out looking kinda light, so I know the motor is running a bit lean.

I just thought it was strange that one intake valve was clean and the other was not, on the same cylinder fed by the same TB. And the same two injectors. With the same fuel. And the same air.

[Degsy]

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Valve adjustment absolutely can cause inconsistent carbon deposits on the valve.