Bike is running very strong up high with the current fueling and airbox setup.

MCM
Full FMF Q4 plus Powerbomb header
Airbox Lid OFF
Lightly Oiled HiFlo filter
132 main jet (sourcing a DJ 144)
needle 3rd clip
Slide drilled bigger than stock (previous owner)
Stock slide spring (have DJ spring)
Stock pilot 35
Kouba T handle 3 turns out.

WOT and this bike starts to gather speed fast. IMO scary fast for the brake power. Pulls hard from 7k+ all the way to redline.

Midrange seems weird. There is also a sharp drop off when I left off the throttle. I thought it might be the pilot being too lean and the mid to upper being fueled more, but after reading more about the air bleed hole on CV slides my thoughts go to that.

My question is about the size of the air bleed hole on the slide. Trying to troubleshoot the problem before diving back into the carb.

Airbleed hole on the slide... It's been drilled out, and the MCM does wild things to the CVK...Stiffer stock spring might not be enough to slow the operation of the diaphragm if the hole has been drilled.

Reading about the CVK34, it is highly recommended to not drill out the hole. I know Dynojet includes this as part of the 2206 kit, but they don't account for the demands of a MCM. Other bikes might have similar intake demands of the MCM, so the warning not to drill would apply to them from stock as well.

A klx250s or klx300 with oem cam configuration might not notice a difference between drilled slide, DJ spring, stock spring, or a combination of them. Most people say a drilled slide or softer spring increased throttle response, but with the MCM maybe that bandaid is not needed?

I've read that the slide can "flutter" if the spring is too soft, ie in a vintage carb. Some folks even preload the spring with a coil on the nylon piece. I don't think I'm feeling a rapid frequency of change occuring in the venturi like a flutter, but perhaps too much vacuum in the diaphragm too fast. If the spring cant control the movement due to the air bleed hole being too big, that's not good right? :P

Someone with a better understanding of the CVK34 or MCM may want to lend their thoughts. The bike runs pretty damn good for now, but I would love to be able to loft the front end a bit easier.

 

You have to know that you are running the bike extremely lean right now..

What are the chances of keeping the RPM's below 7.5K until you get a DJ144/K158 main jet in it..? If that is not gonna happen then you really should put the airbox lid back on (sans snorkel) until you get the right jet.

You are perfectly fine with stock spring + 7/64ths lift hole.. You might check to make sure the hole is no larger than 7/64ths..

All this "stuff" about keeping the lift hole standard size is due to "us" finding out that, with our current selection of needles, it improves throttle response, midrange power levels, and gas mileage, when used with my "full exhaust" recipe ( like you are running) or with either of my recipes sans MCM..

Otherwise, with our current needle choices - even on 1N, the midrange can overfuel.

BTW, "seems weird" ain't gonna cut it - assuming you are trying to describe a malfunction.. Once you have the proper main jet, perhaps the "seems weird" will go away..?

 

Yeah, they really run great when lean until they ka-boom or blow.

 

I agree that the 132 main would be lean with the airbox lid off for most set ups. The dial a jet I am running should be adding enough fuel to dismiss any dangerous lean conditions. I can't prove my h.p. but it sounds like the same fun you are experiencing with bigger main jets.

Lets say you don't agree or don't know enough about snake oil to comment.

I put the lid back on. Running the 132 main, 3rd clip on the needle. Still has no ***** down low, and now I can really feel a miss or hesitation around 6500rpm.

Another case of MCM messing with CVK34?

 

Since the slide operation shouldn't be effected by the size of the air hole, and I'm following all the other directions properly... why does the bike feel like it's lacking in the midrange?

MCM mod with 132 main, kdx snorkel and 3rd clip should have alot more low to midrange snap... pilot too small? Clutch slipping? I expected the bike to flip over backwards with a 13t sprocket and MCM....

 

Oh, Dial-a-jet... I have no information or experience with the Dial-a-jet.
So, I have no help to offer - directly concerning your fueling.

However, there is no such thing as "Another case of MCM messing with CVK34?"
The MCM does not "mess" with the CVK - unless a CVK was screwed up to begin with.. It works perfectly with the CVK..

And, the size of the slide lift hole does alter slide response - it makes the slide respond quicker to any change in vacuum. And this alters the fueling curve by quickening the lifting of the needle..

Since I have no idea what the Dial-a-jet might be doing, I have no idea what could be causing issues..

 

To get it to flip, your going to need a new cam and a slide carb, sorry, just ain't going to happen with what you got.

 

Well actually, with proper fueling, your setup should be pulling power only non-assisted 1st gear wheelies and 2nd gear wheelies on a power shift at/near redline.
Of course, your body mass, height, and technique all play a part.. My daughter can't get my KLX to wheelie at all..

 

I've come to grips with the fact that the bike won't flip over if I sneeze on the throttle. This wasn't ever my intention with my 2007 klx250s, nor was it with the other two klx250's I owned. It was a statement born out of sheer frustration. Before buying my third klx, I told myself I wouldn't get into the carb. Now that I am well into changing the fuelling and air flow, no one else is to blame but me.

I've also come to accept that my constant tinkering with the carb is likely the only thing causing any condition other than "good"

After reading through the entire saga that is found at :

" https://www.kawasakiforums.com/forum...welcome-43229/ "

I conclude that my lack of scrutiny is to blame, and a loss of patience resulting in the hasty reassembly of the carb.

As it stands, I'm running the following set up:

MCM
132 Main jet
3rd Notch on DJ needle 2125
HiFlo Air filter
Air bleed hole stock diameter (verified with a drill bit. Not drilled out to 7/64 as I had thought)
DJ slide spring (installed after realizing bleed hole was stock diameter.

Dial a Jet turned all the way down. At this setting there should be little to no fuel being added to the system, unless the system is lean. It's either inert, or helping.

All in all, there is no longer a sputter or miss at 6500 rpm. I had already been through this before, with stock exhaust, MCM and 120 main. Installing the 124 main seemingly fixed the issue at the time, but after having the same issue at the same rpm with higher airflow and richer jetting... It all comes down to the slide seating properly.

Only change I made between tests was reinstalling the DJ spring, and the problem cleared up. I think most of us focus on the mod, and attribute a change based on that while overlooking something like carb slide operation. After reinstalling the DJ spring, my throttle response is quicker. Also the bike has more pull down low, between 4k and 6k.

No more missing or hesitation while cruising at 6500rpm, same problem I had with completely different jetting...

Seeing as how this problem already happened, immediately following a rejet (stock main to 120 main and DJ needle added) and was fixed by again opening the carb up and going even richer (124 main) detail being with the carb off the bike, slide seated meticulously and movement verified with vacuum.

then again happening after a rejet, and fixed by a more thorough reinstall (although this time I did it with the carb attached. Took a chance by not verifying slide movement, got lucky). The point is I focused on the carb components, not how they would make my bike go zoom.

 

Outstanding! You're a changed man, you've seen the light !


Regardless of who you are, or who you think you are, if your CVK "acts up" after you install a known working setup, you f%@&'d it up - hopefully not permanently..

Back when PWJM and Snowdrifter were having problems, we had no clue what could be wrong.. Since then, others (and now you) have "fixed" their stumbles with careful attention to diaphragm seating..

PWJM and Snowdrifter - same problem, no solution, nothing but mystery.. I worked with PWJM for over a month - had Snowdrifter send me his faulty CVK - it ran my bike perfectly right outta the box it was shipped in... It's taken a lot of drugs and therapy, but I'm over that event.. I think..