I have an issue that seems to happen once a week.  I'll fire up the bike and it seems to be running fine, let it idle a bit to warm up, hop on the bike and take off.  Get to the turn at the end my street, let off the throttle, it starts to stutter and dies.  Throw it in neutral, hit the starter, crank hard on the throttle and it fires back up again.  

It will continue this pattern for a while, and if I crank hard on the throttle when it starts to sputter it will chug for a second then fire back up.  

Turn around, head back home.  Check fuel level, plenty of gas.  (originally thought it might be due to low gas and fuel shifting off of the fuel pickup during braking)  Check oil level, plenty of oil.  (I thought that maybe engine was trying to seize due to low oil)

Fire it up again and turn the throttle till its at a high idle so it doesn't die, hold it there for a few minutes.  Get out on the road again, no more issues.

This will happen maybe once a week. I have noticed that after filling up the tank, I will get a slight leak around the gas cap (gas level is high enough to slosh up to the cap during breaking or due to vibration).  Could it be a vacuum issue due to a bad seal on the gas cap?

verslagen1 wrote on 10/10/11 at 07:41:50:

Agreed, but if it runs good at high speed, it is doubtful that will fix the problem.
Try it on "prime" see if anything changes.

Ok, ever since I've sealed my gas cap leak, at high speeds (65mph) I have the "out of gas" problem.. first 2 times I had to pull over and breath the gas tank, then I started flipping the pet thingy switch around while doing roughly 65mph.. does anyone think I should go ahead and throw in the Raptor 660 pet thingy or get a new vacuum hose?

How come I can't play with my thingy but I can play with my petcock?

Built2Last wrote on 10/10/11 at 12:01:56:

If it's just since you sealed your gas cap,... it's your cap vent...
Before you sealed it, it was getting air through the seal,.. now, it's trying to suck through a clogged cap vent...

You need to disassemble the cap and clean... or try just spraying the crap out of the cap with carb cleaner...

It is not dirty.


























Ok so it might be, I'll check later, I'm about to go and mess up the carb... but I want a Raptor 660 pet c0ck anyway...

Verslagen gave you a good answer. It is easy and cheap to replace the vacuum line. And if it doesn't have clamps on it, get some. The OE petcock will not function without proper vacuum. It does not always malfunction at high speeds, but sometimes in cooler temps, and often when rolling off the throttle. Drag racing launces and running through the gears up to speeds over 70 made mine mess up. Do the easy, cheap things first. jmo

The Raptor Petthingy is like $20, and swaps out in like 5 minutes.

If you're not gonna ride during the winter and do some wrenching might as well check your cam chain tension-er and maybe throw on the Verslavvy.