Well, I'm still running the stock air-box.  I just have the filter portion changed out.

And it really sort of happens at all speeds, not just highway speeds.  If I really get on it, it just breaks up and can't do anything.




Update:

Shimmed the needles, problem got worse.  Where I used to be able to get it to red-line as long as I didn't full throttle, now it just won't get over 8-9k at all.



Talked to some other guys I know, one in particular is very knowledgeable about this kind of stuff, and we're now thinking the culprit could be ignition related.

As we're adding fuel the problem gets worse, and the bike on a whole is still running lean, so it could be that when we add more fuel it's putting out the fire, so to speak.

Could be bad plugs (wrong gap or physically broken), bad wires, bad coils, or bad timing.


Plugs are cheap, I'll toss some new ones in and see what happens.

Had this happened once.  Everything said fuel starvation, and I mean everything.  Looked at ignition, found out after 2 days it was a CDI Ignition box failing.  Replaced, and ran like new.

Start with ignition pickup, coils, wires, and plugs.  That's easy.  If not, it may be your CDI box.  Check all connections too for corrosion.

Quote from: jestercinti on June 24, 2013, 12:52:10 PM
Had this happened once.  Everything said fuel starvation, and I mean everything.  Looked at ignition, found out after 2 days it was a CDI Ignition box failing.  Replaced, and ran like new.

Start with ignition pickup, coils, wires, and plugs.  That's easy.  If not, it may be your CDI box.  Check all connections too for corrosion.

In the process of weeding out electrical now.  Plug wires look a little ratty on the ends, might as well change them.

One piece at a time till we figure it out...

IF YOU ARE TUNING AN ENGINE YOU NEED NEW PLUGS OF RIGHT GRADE . NOW THAT YOUR NEEDLE IS LIFTED IS YOUR MAIN JET ABOUT 145 IF ITS LARGER SAY A 150 YOU WILL DEFINITLY  BE TO RICH ..WHEN TUNING AN ENGINE YOU NEED ELECTRICS PERFECT ,LEADS PERFECT,  BATTERY PERFECT, AND FLOAT NEEDLES THAT DONT STICK .FLOAT LEVELS AT THE RIGHT HEIGHT ,NO AIR LEAKS. INLET AS WELL AS EXHAUST IF ANY OF THESE ARE NOT RIGHT YOU ARE JUST WASTEING YOUR TIME TRYING TO TUNE IT,YOU WILL SEASAW FROM ONE PROBLEM TO ANOTHER .

Well, I've got brand new NGK Iridium plugs in it, my main jet is currently 135, battery is good, I'm checking wires/coils ASAP, float needles are free, floats are set right, fuel flow is good, no vacuum leaks, no intake leaks, no exhaust leaks...


All I can do now is go down the list of electrical starting at the end closest to the motor...

Maybe you are lean at idle, and rich at WOT.  That might cause you to see white plugs and valves, but you could still be rich on the top end.  With the stock airbox and a K&N drop-in filter, the suggested jetting on the matrix is 127.5 mains.  I personally got tired of messing with the different airfilter mixture issues, and I went back to the stock filter with 125 mains and I've been happy since.

Quote from: bombsquad83 on June 25, 2013, 06:09:04 AM
Maybe you are lean at idle, and rich at WOT.  That might cause you to see white plugs and valves, but you could still be rich on the top end.  With the stock airbox and a K&N drop-in filter, the suggested jetting on the matrix is 127.5 mains.

That's what I'm thinking, I'll have to order some bigger pilot jets.  But wouldn't the main jet affect midrange more than the pilot jet?

If I have a free-flowing exhaust, that'll need bigger mains in addition to the filter mods.
Does 135 seem too big for a straight-pipe and the k&n?

here is a good way to tune your carb .Mark your throttle grip with a white mark  then twist the throttle gently till you have taken the slack out of the cable now mark the housing oppisoite the mark .wind the throttle round till it is wide open and make another markon the throttle grip oppisite the mark on the housing .Now divide the gap between the two marks into 4 equal gaps .You can now determine which part of the throttle circuit you want to tune ,first 1/4 throttle is for the idle circuit 2nd 1/4 throttle is for the slide circuit third 1/4 throttle is for needle circuit and wide open throttle is for the main jet  All these curcuits overlap into each other to give a smooth transistion into the next.