I built a RYCA type mod last year. Lowering the front and raising the rear. I have done a raptor petcock conversion as well as many other mods. Early this year I discovered fuel dripping from the air filter. I removed the carb cleaned and adjusted the needle valve on the carb new gasket on the bowl and installed the raptor petcock, drained the oil and did a cam chain mod. Everything seemed great. Today I walk into the shop a smell fuel. The petcock is off and there is a puddle of fuel under the bike on the lift. Looking in the oil sight glass it looks as if there is fuel in the engine. My question is WTF?  Any ideas guys?  The petcock is obviously leaking but doesn't seem to with the tank removed.  The carb does have a forward lean as does the engine.  

Is that a Chinese Raptor?...  If your observations are correct, it clearly needs new rubber inside...
If it's not really in the oil,... I'd say replace the float needle and seat...

I had the tank off for a couple of weeks recently waiting for modified cam chain adjuster and there were no apparent leaks then.  Changed throttle cable and rode maybe 20 miles seemed fine. Then I noticed what I thought was an oil leak but apparently it was a grime gas mixture. I had this problem before as I mentioned above. I cleaned the needle valve assembly, placed the float in a cup of fuel to make sure it was ok then blew air into the fuel line as I gently raised the float to cut off the flow with only light pressure.  The bike seemed to be fine for several weeks then.....
I will order a new float, seat, and needle valve, and check the petcock.

Apparently petcock is China knock off.  and does leak in off position.  Orderd Genuine Yamaha Raptor 660 YFM660R
Prt # 5LP-24500-01-00
Part is stamped H14


Also ordered carb kit and float from Suzuki Dealer.
I will change oil again and start over with carb and petcock.

Pretty sure I have a clean engine now.

one more question.  When I install the new float and needle valve the Clymers Manual only list a measurement when setting the tang on the float to get the proper height.  When I cleaned it I put a fresh hose on the inlet and blew through it and adjusted the tang on the float until light presure on the float cut off the air flow.  Is it better to just measure, or is there a better way to set this.  
When I parked the bike before the puddle it ran smoothly and idled perfectly.  There was no backfire or sputtering at any point.  So no apparent fuel issues.  Its just bothersome to keep having this problem.

You sure thats upside down?

Alternate method for the inversion challenged...

Quote:

The Mikuni manual actually recommends adjusting the float level as a tuning option.......when one main jet is too small and the next size bigger is  too big!  They must really be doing some "fine tuning"!

3. Low end (full throttle / 2k-3k) Float height (AKA fuel level & how to..)
To get best low end power, set float height so that the engine will accept full throttle in 2nd gear from 2.5k to 3k rpm at minimum. Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring.

Base settings are usually given if a particular application has a history of fuel level criticalness. The Fuel level height in the float bowl affects full throttle/low rpm and, also, richness or leanness at cruise/low rpm. Reference: a bike that runs cleanly at small throttle openings when cold, but starts to show signs of richness as it heats up to full operating temperature, will usually be leaned out enough to be correct if the fuel level is LOWERED 1mm. Check out and RESET all: Suzuki (all), Yamaha (all) and Kawasaki (if low speed problems occur). Needless to say, FUEL LEVEL IS EXTREMELY IMPORTANT!!!