This is the Raptor part no.  5LP-24500-01-00
2003 Yamaha Raptor 660 YFM660R

NOTE... ( all Raptor 660 petcocks fit,... I included a specific model/year for internet ordering, and anal retentive counter salespeople...) (Raptor 350 petcocks won't fit)...

FWIW,
I had a brand new bike. The first week I had it I removed the stock petcock, warranty be darned. That thing is an engine failure waiting to happen. Of course I fitted a YAMAHA raptor petcock to replace it.

P.S. anybody want to buy an unused stock petcock.

You've got it Justin.

Is there any reason specifically to replace the petcock if the OEM one is working fine?
I'm always faired well going off the premise "that if it ain't broke don't fix it".

BTW- I do have the Raptor petcock sitting in my toolbox just in case the OEM one does fail.

batman wrote on 04/17/18 at 09:14:44:

Blueraven, It's not if it fails , it's when it fails. the carb pulls the least amount of vacuum at WOT , and can fail at the worst time . as in a passing ,and the diaphragm closes and the motor dies ( and so may you).

I see you're point.
I guess I'll go ahead and swap it out since I already have the Raptor.

Thanks,

Hi I did a vaccum test and the needle jumping all over so my wife showed me book that says that could mean a head gasket problem so my question is  do u think the head gasket would be bad

Aaronjkjkk wrote on 03/26/21 at 22:49:46:


Yep, I tried putting a vacuum gauge on my little Ninja.  The needle was swinging so fast it was just a blur!  The intake manifold is subject to wild pressure pulses....and it is normal.

The stock vacuum petcock works for a while - then it doesn't.  Unfortunately the failure mode is not always the same and can cause owners to look for problems that don't exist.

One mode of failure is the diaphragm gets stiff, and it begins to limit fuel flow.  As noted in DragBikeMikes original comment the engine vacuum drops as the throttle is open wider....and very often the engine will run fine until the rider gets out on the interstate and rides fast.  This failure is a real disaster waiting to happen - 75mph in traffic on a 4 lane highway and your engine quits!  Riders often claim that the bike starts back up after sitting for a while - which often has folks looking at ignition or carb problems that don't exist.

Another mode of failure is the diaphragm that gets porous.  This causes fuel to leak down the vacuum line to the carb.  This can result in the engine running rich if the leak only occurs while the engine is running - or it can leak gas continually and fill the air box and engine crankcase with fuel.

For a reliable running bike - it is important that you replace the stock vacuum petcock with a manual one.  And then you need to remember to turn the petcock on when you start your ride each day, and then turn it off at the end of each day you ride.  I am a bit more focused about the issue and at the STOP sign down the street from my house I reach down and turn the petcock OFF.....and by the time I reach my driveway the engine is running out of gas (This allows my bike to be parked with a nearly empty float bowl and reduces the chances of my jets being clogged up when the fuel evaporates or gets stale).