A repository of CVK issues, symptoms and solutions. Please read the entire thread before determining a course of action on your bike..

Your bike runs fine, but you want more. You take the carb apart, put in a known working "setup" or kit, and now it won't run right. See, in here, where you may have "gone wrong" while handling /reinstalling your carb.

So you've tried to get that "Biggy" power I and others are talking about - but your bike won't do it.. It won't run right with the latest forum setup and you are doing everything right. So while Murphy ( owner of Murphy's law) sits back and laughs, you decide the wanted setup (and power levels) "just doesn't work for everyone" and go on with whatever seems to run your bike.. See here for help.

Or you've bought a used KLX that doesn't quite run right but you figure you can fix it. Perhaps, in here, you can find an answer - without having to become a CVK expert.

Or your steed has developed an issue and you need a starting point for a fix.

Perhaps you've just completed the MCM and it's just not running right. You want to blame the MCM. Fact is, the increase in TRQ will place new demands on the carb and could reveal issues that didn't matter much before..

Hopefully we can beat Murphy, and get your wanted setup running.

Firstly, lets all agree - CVK's and KLX's are not magical - they are mechanical.

So here is the cold hard truth about intalling a carb jetting kit or jetting components -
If your bike ran perfectly fine before you took the carb apart, and you are using a known working setup, and it doesn't run well after, you've done something wrong or something went wrong during your handling of the carb, and was not detected.

 

Edit with new information on Midrange bogging/stuttering: It has been member verified that this issue is caused by the below, and goes undetected and uncorrected during multiple carb teardowns/reassemblies while trying to fix this problem. This mistake has plagued more than a few owners. It is not a trivial task to reassemble the slide, spring, and cap correctly - it takes a great deal of "attention to detail". You will be tearing down your carb continually until you get it right, so it's best to get it right the first time.

The metal cap to the diaphragm (Top Cap) - it must seat/seal perfectly. If it's seating surface is bent, tweaked, or otherwise, it must be fixed/"trued up" or replaced.

The spring must be indexed correctly into the "indexing tangs" inside the Top Cap, during reassembly.

Diaphragm damage or not seated correctly. This operates the fueling of the bike by raising and lowering the needle. If it is damaged or not sealing correctly, fueling issues will ensue starting about 3k-3.5k (under load or WOT) on up.. Some CVK diaphragms seat themselves easily, some do not. It is not a trivial task to ensure a proper seal if you have a "problem" diaphragm so care and attention to detail are important.

The lid/cap to the slide area WILL NOT make the rubber seat into the groove, so do not bolt down the cap until you are sure the diaphragm is seated correctly. I have noticed that the cap will go metal-to-metal with the carb body when the diaphragm is seated correctly in the "groove" of the carb body - I have also noticed that if the diaphragm is ever-so-slightly off of this groove, the cap will not finger push to metal-on-metal contact with the carb body. Again, the cap will not "seat" a misaligned diaphragm - do not bolt it on thinking it will..

it is said to soak the rubber in hot water to help it seat well..

SLIDE LIFT TEST: manually lift the slide briskly and completely "up" with a finger . When malfunctioning, the slide will offer variable resistance to being lifted. When corrected, the slide will offer "even" resistance. Obviously, the slide should quickly and smoothly return to the closed position. This test should be done and passed before the carb is reinstalled into the bike..

Not sealed properly, your bike will experience aberrant slide behavior which will cause all kinds of crazy symptoms including midrange stuttering/bogging.

EDIT 10/1/2017: One member had apparent bogging/stuttering and fixed it immediately when he read in here about indexing the carb correctly. His carb was tilted.

 

The DynoJet kits come with 2 washers for use with the needle - you must use both washers. You will need to "Dis" and "Re" assemble your carb until you have managed to install both washers... Without them, the needle is not stabilized in the slide and can "jiggle" up and down and all around...

If running one of my setups: DJ140/1N and DJ144/1N uses both washers super-glued together and resting on top of the clip - or super-glued on top of it.

Fuel screw damaged - used bikes may have had previous owners that were not as savvy as you are. If the fuel screw was torqued too tightly closed, there may be damage to the seat and the fuel screw itself - results include inability to set fuel screw to known working settings with proper results..

 

Clogging in PAJ, and/or Pilot jet.
Our CVK's do not ever meter raw fuel into the carb airstream. The pilot jet along with the Pilot air jet(PAJ) emulsify air and fuel - this A/F mix resides in the pilot jet waiting to go past the fuel screw or directly into the air stream through the transistion ports when the throttle is cracked (simulating an accelerator pump). This A/F is created continuously as it is used. The pilot system fuels the bike at idle, decel, and a few other instances with high RPM at low throttle setting - such as cruising in second at 3-4k RPM's @ 1/8 throttle.. Point is, it flows A/F during very high vacuum operation. Such high vacuum will occur anytime the engine is running with the throttle closed (butterfly closed), or under no load or light load with throttle/butterfly under 1/4.
Clogging in either the PAJ or the pilot jet(which has tiny holes) will affect the fueling of the pilot system.

 

Clogging in Primary fuel system.
Components of interest to this post: MAJ, Emulsion tube, Main Jet.

Air enters the Main Air Jet(MAJ) and is mixed with fuel in the Emulsion Tube. See the MAJ port in the above picture. The fuel enters the Emulsion Tube from the main jet below - (The main jet screws into the bottom of the Emulsion Tube).. This A/F is what fuels the bike from about 3k on up to redline while under load or @ WOT. The (needle/slide/diaphragm/slide spring/needle jet) controls how much A/F gets to your engine starting about 3K to 6.5k under load or WOT.
After which, only the needles' point and diameter at its' end, as well as the size of the needle jet(which sits on top of the Emulsion Tube), are in the way of the A/F flow through the Emulsion Tube into your engine..

Clogging of the Emulsion Tube, main jet, and/or Main Air Jet will affect all fueling above 3-3.5k

 

Butterfly shaft seal: Very important for well used or older bikes. I think this issue may prove to be the number 1 reason you can't run high performance setups. Various symptoms which, at this point in our knowledge, seem to have a stumbling midrange @ WOT as a common denominator when you try to increase fueling with a "known working" setup.

Neonarc has data on this issue: https://www.kawasakiforums.com/forum...replace-43126/

 

Float level: The level of fuel in the bowl governed by the float system(float system needle,seat, and setting on the "tang" of the floats that operate the float needle)
Do not set a disassembled CVK down, on its' float system - you'll "bend up" everything and destroy your float settings !

A leaking needle seat will leak fuel out of your bike when it is sitting through the overflow tube.
This level must be set correctly for proper fueling of the low RPM as well as the transition to the primary system at about 3-3.5k.
Great low RPM throttle response and power as well as seamless transition to the primary system are hallmarks of a properly set up float level. And you will never know if you're getting the proper throttle response and power in the low end until you know the float level is correct.

Use the "clear tube method" to quickly verify correct fuel level without any disassembly. Level should be .5mm above carb/bowl mating surface, plus or minus 1mm.

Or, if the carb is off the bike, hold the carb upright and then slowly rotate toward upside down - stop rotating the moment the float closes and measure from the bowl gasket surface to the top of the float - make sure it is 15-17 mm.

 

Never run a DJ spring with a drilled slide. For instance: So you bought a great used KLX and now have the DJ kit. You put it in and "NO JOY". Overfueling or underfueling (depending on how you choose to define each) above 3-3.5k until somewhere around 5-6k .. If your slide lift hole is drilled, you will be able to slide the back end of a 7/64 drill bit in and out of it - if it won't slide into it, your running a stock lift hole..

Take whatever measures are necessary to insure you are not running a drilled slide with the lighter DynoJet spring.

To restore a drilled lift port, JB weld it closed and very carefully re-drill with a 5/64 bit - runout and wobble must be kept controlled so as to not create another 7/64 hole !
If you want to "install" a drill bit and JB weld around it, use a 3/32 bit.. If you are running lidless+lidless DJ144/K158 main jet carb setup with a full exhaust system but without the MCM, it would be a good idea to JB weld around a 5/64 bit to further help control fueling below 7k rpm via a very slightly undersized lift port.

 

Incorrect re-assembly of the carb to airbox boot. And/or not correctly indexing the carb into the intake manifold, leaving it "tilted" left or right. A tilted carb will exhibit bogging/stuttering while riding..

The airbox boot issue is a very common occurrence.. You get er all back together and are ready for your first power wheelie - only to find out you've picked the wrong day to quit sniffing glue..

Get it seated correctly ALL THE WAY AROUND the carb bell.. Also, quit sniffing glue..

 

Leaking plug on the intake manifold nipple. You long ago removed the air injection system and plugged all the open nipples. If the one on the intake manifold (the item between the carb and the engine) is leaky, you'll never run right..