I finally took the plunge this weekend, and removed the airbox...and installed a homemade "intake" w/ a K&N air cone filter.  Here's what happened, and why I'm confused...

After finishing it Saturday night, I took it a couple miles down the road & back, and it ran flawlessly!  I was amazed at the difference in power, low end torque, and throttle responce that were added.

Sunday afternoon I went for a two hour ride, and again it ran perfect.

Later that evening, during the last five minutes of a one hour ride, it began to hesitate, and what I would describe as "fluttering".  I thought that I might be out of gas, but it's got about a half tank.  I let it sit for about an hour and took it a couple of miles down the road, and again spitting & sputtering!

It seems to accelerate and decel ok, but when it levels off at any steady speed, it flutters.  I realize that I've changed the way the carb gets air, and this could change the way it runs...including a possible rejet, but wouldn't that show up immediately?  Why after so long of running great?

Any ideas?
Anything else it could be that I'm missing? (I was real careful as to make sure there was no "trash" in the intake when I put it on...I thought)

Sorry for being so wordy, but I am NOT a carb guy, so I wanted to explain it as best as I can.  Thanks for the help!

verslagen1 wrote on 06/24/13 at 07:05:37:


please define "test".

im running the same set up, make sure your all sealed up at every connection of the intake, i used rtv.

Don't think I would like the air filter right next to the head pulling hot air from it.

apache snow-FSO wrote on 06/24/13 at 08:53:34:


I was a little concerned with that...as a matter of fact, that was the reason for letting the bike sit for an hour.  I wanted to see if cooler air would make a difference.

The pic doesn't show it from that perspective, but there is actually about 3" between the two.  It makes for a bit of a wide seating position...but I got a lot of room with them there bicycle pegs.

So I attempted to "test the petcock".
First I went for a very short (2 mile) test ride to see if I can get a baseline for what point it starts missing, so when I do the test, I can notice any difference.
I removed the vac line & sucked on it to see if there was any fuel leaking, and no, it was dry.  I then proceeded to block off both the hose & the carb, and set the petcock to PRI.  I barely made it out of the driveway & it died.  Wouldn't start.  Sounded like it was starving for fuel.
pulled out the two plugs, placed the line back on the carb, set the petcock back, and it started right up.

So, any ideas?  Am I looking at a bad petcock?

Yes, right opposite of reserve & perpendicular to on.
It's a '97, but I was assuming they're all the same.?.?

Get yourself a Raptor petcock and be done with that demon thing.