Doug B wrote on 10/30/12 at 15:30:25:Oldfeller--FSO wrote on 10/29/12 at 09:37:14:
And now, as a reluctant convert, you get to give your initial impressions of your bike's performance
after you Raptor it, that is.
Any felt differences?
Oldfeller - apart from the safety/reliability issues what are your thoughts/experiences in switching to the Raptor I'm curious as to what performance gains could result in going to a gravity fed petcock ? doesn't the vacuum operated type only give us an automatic shutoff ?
I have to echo Serowbot, the performance increases you see are a result of getting a
consistent full flow of gasoline. Nothing more.
When a vacsucker begins to fail you have lots of times you don't get the optimum amount of gas delivered to your carburetor -- not enough lack to cause you to sputter and die stone dead, but to just run poorly,
Your carb is regulated with the gas level just about at the top of the bowl -- that is its designed gas pool level. When you start running that level constantly up and down the depth of the bowl, your bike runs like crap some of the time.
When it is below mid point, you are running LEANER and LEANER as it goes to zero.
Problem is, this likes to happen when you are on interstates and major roads and you are trying to go fast.
I used to tease Verslagen with this scenario -- going 80-85 on the 6 lane and the vacsucker begins to malfunction, bowl level drops and you start to lean out and you lose power going up a hill. What does your hand do? NEED MORE GO POWER, so you roll the throttle on and increase the demand for gas on an already partially empty bowl. Now you are running really really lean at full throttle, overheating your piston and your ring grooves do a little bit of close up due to mild piston wall scrubbing. Vola !! Your bike begins to consume oil ....
(this was back in the days of the petcock wars, which we no longer have to do since we have seen this same thing happen on tear downs just this past month)
Vacsuckers can affect your bikes performance by starvation and by alternate gas paths. Failing diaphragms can pass a trickle of gas down the vac tube to the carburetor body, where it becomes vaporized making your rich at low speeds. This error shows mostly at low speeds as the amount of gas leakage is small and has most effect at lower speeds. Now you are yo-yo'ing between rich and lean.
So, there are five major known vac petcock failure modes that folks have stumbled over. Each of them can make your bike run poorly to some degree. A Raptor makes all five of them stop, instantly.
Most Raptor folks say the Raptor makes their bike peppier and run better.
I wonder why .... 
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