Guys - the issue that lead me to retrofit the stock airbox (and rejet plus fit a different muffler) - is still there.

Bike idles fine, but on slow to medium take-off throttle is stutters a little and loses power, like there is no ignition or too little fuel now and then. At full throttle, the problem is almost gone. The plug is brushed and burnt clean of any residue, battery is full. Fresh gas.

Now...I did NOT take off the top of the carb when rejetting. I blew the floatbowl things and channels clean when apart, but I must have missed something.  Could this be the needle jet clogging up? The symptoms are identical to before I started tearing things apart. Setting the petcock to Prime or RES changes nothing.

Why oh why didn´t I split the whole thing while at it? Or could this be ignition-related, like in oxidized connectors/intermittent earth loss and/or failing CDI box?

Hm. The funny thing is that the bike ran fine all winter. I put 800+ km behind me without even a single backfire or any stuttering at all. Now, with weather getting 15-20C the bike starts acting up. Could the warmer weather make it into a white spacer issue?

(Edit: I did that mod (shaved half of it off) on the young ladys´bike, as a routine thing, but not on mine)

I will. Thanks for the advice!

Serowbot wrote on 04/29/14 at 07:59:24:


Oh......That could be it as well!  That might also explain why it ran OK a while ago - but doesn't now.  Time for a spring cleaning!

Yes, probably a clogged needle jet or a sticky slider.

Like a miracle, it disappeared. I took the bike for a healthy spin in order to cook it properly. And yes, after a series of stop-n-go kilometres, some stretches at full throttle and almost redlining (oh, the joy with the new "silencer" )  the issue disappeared magically. Phew.

Smiling ear to ear after that, I took a break for some 20 minutes, overlooking a peaceful "sunset over the Öresund and Copenhagen" scenery. Fed up with that, I went back to bike to find the battery totally flat. I forgot to switch off. Lights and all on...

Thank you, magic I had to 2nd-gear jumpstart the little mofo with whatever juice was left for the ignition...but that was o cool price to pay for this issue

<<all smiles

Do you have a fuel filter on it? After blowing it out at high RPM and now it runs fine sounds like crud in the gas.

He's got a stock petcock filter ????


Do you still have a stock petcock ???!!!!


..... and nobody asked him either.


The stock petcock going bad can give the same sort symptoms that you have been describing up thread.

Yep, the horror of it all, the stock vacuum actuated petcock.

                   

List of things he's tried:

Pulled and replaced stock air box
muffler
rejet
plug


Issues diagnosed

Sticky slide
Half spacer
Midrange lean
Ignition related

Now, let's see what remains after he gets his Raptor in place.

People wonder why I keep telling folks to yank the stock vac petcock off their bike first thing whenever they START their Mods -- because if you don't you get lost in all the muddy water that it creates spontaneously and sporadically and occasionally on its very own.

The vacuum level needed to run the stock vacsucker correctly DEPENDS on all the stock pieces being in place, especially on the air filter end of things.  Start your mods before Raptorizing and that practically guarantees a world of confusion & trouble soon to arrive.

Sad thing is that folks flat screw their bike all up messing and fixing with this and that and the other thing and then have to go UNSCREW it all once the Raptor goes on and the murky water abates.