Sweet!! Thanks!! I'll update my signature.

Snorkle pulled, lid on, airbox screen removed with UNI filter, FMF power bomb header with Q4, idle jet drilled .018", pilot K40, main K140, 13t front sproket

I'm open to changes!! Kept the lid on the airbox so far because of the added noise everyone mentions. But honestly I've never run without it. Maybe that noise doesn't matter. I've put this much effort into adding performance, maybe that should be my next step.

 

What about your needle, needle clip position, slide spring, slide lift port..? are they stock or not..?

 

Dynojet 2152 needle on 3rd clip with the 2 washers on top, Dynojet spring, slide drilled, idle screw 2.5 turns out.

 

To unleash monster "KLX300S" power:
1. Your DNO228 needle: Clip on top notch, super glue both washers on top of the clip (so they won't ever fall off, otherwise they will, and both washers MUST be used. ) ...
2, Redo the lift port to 3/32 - use JB weld and a 3/32 bit to accomplish this ( never drill anything inside a CVK - for any reason - regardless of who you talk to or what you read..)
3. Install a K160 or DJ146 main jet.
4. Reinstall the/a stock slide spring.
5. Remove the airbox lid - hide it in the attic - UNI should be very, very, lightly oiled, or run dry (pavement only)..

This recipe is tested and proven - do not deviate from the above 5 steps - component interoperability is key and deviations destroy this recipes' "tuned" interoperability..
Results are 1st and 2nd gear power-only wheelies, and 3rd gear power wheelies with a tug on the bars !

P.S. You may be .5 to .75 turns too far out on the fuel screw, with the #40 pilot jet.. With hot-engine idle speed set to 1250-1300 rpms, use the midway point between idle drops procedure to find the perfect setting. Or, if using the stock fuel screw, reset to 2 out for near/at sea level..

 

Ok, I will order a new jet and try this combo.

Thanks for the insight!!!

 

Good for you !
Just do yourself a favor and don't deviate from the recipe - power robbing midrange overfueling is what will happen if you do.

 

 

Will it rev to redline with a powerful linear pull in gears 1 and 2 ?

If so, then yes, you should check for fuel delivery problems - the stock inline fuel filter, bowl vent hose routing, tank vent hose routing, etc etc..

 

I pulled the carb back of yesterday, tore down and inspected everything. Could not find an obvious issue or problem. I do have that stock little inline filter, it was clean. Reinstalled and same issue. Just seemed to starve above 6k rpm. Start up, warm idle, acceleration in 1st thru 4th all seemed strong. Full throttle in 1st and 2nd are brief before time to shift. The 60mph and above it just would not do. Bike studders and starts to slow down above 3/4 throttle. No popping, no change in exhaust sound. So either too much fuel, starving for fuel, or starving for air.

 

Again, the scenario ( that the problem manifests in ) is the highest fuel demand of any other engine operation. If the engine will perform as expected - and to redline - in "lower" gears, fuel delivery to the engine is likely being restricted..

If lower gear performance is perfect, and only extended high rpm, high load, ops create the foundation for the problem to manifest when the throttle is increased, it seems only logical that fuel starvation is at play.

Check the float level using the clear tube method. (see post 7 on my "CVK listing of issues....." link on my signature line)
Check the carb bowl venting system - it must be correctly configured, clear of any obstructions, and fully operational..
Check the fuel tank hoses for proper routing - the fuel tank requires proper venting.
Verify the petcock system is able to provide full flow out of the petcock hose nipple.

Install a new, and correct, spark plug.
Test ride....