[Luke47]

Took the air box asm off and found this on the front cyl. intake valves.. what's do you think may cause this...

 

[loony888]

Carbon on the back of the valves is pretty much standard when they get used, especially on the street.

Those deposits come from the combustion cycle and unless it's being used wide open it will happen, it's a byproduct of big cams and low RPM

 

[Rex Coil 7]

... not sure, but Seafoam might be enough to take care of some (most?) of it. Looney888 is right by the way.

 

[Namor]

Looks good to me. It's just the result of an air/fuel ratio.

A proper map will clean those up without cleaning agents.

 

[nlzmo400r]

You'd be shocked at how much of that crap will come off if you flog the bike long enough with a decent map in it.
I've put used engines in race bikes with NASTY looking valves and after a few race weekends the back of the valves look brand new. Gasoline is a great cleaning agent lol.

 

[rennsportmotorrad]

especially race fuel lol

 

[Zaph]

You'd be shocked at how much of that crap will come off if you flog the bike long enough with a decent map in it.
I've put used engines in race bikes with NASTY looking valves and after a few race weekends the back of the valves look brand new. Gasoline is a great cleaning agent lol.

The doctor prescribes a track day or two.

 

[johnsosn]

probably crank case (oil) vapour cooking on the back of hot (relatively) valves.