So, either the KACR has been repositioned, or your engine starting is not what it is supposed to be.
As you probably have read, a hallmark of the MCM ( when done correctly ) is instant starting (when warm) and near instant starting when cold.

As your bike has previously had, at least, one idiot owner, there is no telling what has been done to the carb.
You will need to determine what internal changes have been made to the carb, and begin the process of restoring it to proper functioning with the correct components.
If you are going to run lidless, you can use one of my lidless CVK setups.
There is no dyno tested and tuned setup for the Mikuni - so you will be using unknown fueling unless you use a dyno to test and tune.

The MCM is not experimental - it is fully vetted - and simply works if done right on a properly functioning engine. It would seem your engines' carburetion has faults that will need correcting before you can realize top performance.

 

So really appreciate the guidance here and your time @Klxster I guess I am following my own advice I tell my to my kids, seek out the experts ( You guys i been following for the past 4 years), with the knowledge the skills and the results to back it up, not your dumb *** friend who has a reckoning.
I would not be surprised about the Carb being dicked with considering the Modified air box funnel, it is a piece of Flexiglass heat molded then secured in place with some unknown semihard/ flexible bonding agent, Not silicone, not glue, See photos

Back of box with mystery bonding agent, good stuff no idea what it is???

Front showing clear flow flexi- glass modified funnel.

 

Oh boy, Its' had a "genius" previous owner. The various airbox lid configurations will alter airflow significantly enough to require adjustments to fueling. I doubt the genius previous owner had a clue what his mod actually did to airflow. We know how to properly fuel a "lid without snorkel" and a lidless airbox. The KDX snorkel further muzzles a "lid without snorkel" configuration.

Good luck, as diagnosing, correcting, and properly setting up your carb is likely going to be a project in itself..

 

Haha genius maybe, and a true craftsman, thanks for the options, toss the lid, rip off the Flexiglass Frankenstein of a snorkel or replace the whole thing and go from scratch.

Keep you posted.

Thanks Geo.

 

@Klxster Managed to get the Big bore in and top end back on this Afternoon / Evening.

The dreaded 1/2 Exhaust MCM is now a full MCM.
I think i'll go lidless and tune the CVK as per the thread. Things are getting cold here I have a Skid Steer, Backhoe and Quad to go over, before Christmas.
Current results below. I believe based on the great direction I nailed it.
I also pressed out the KACR so that's gone as well.
Cheers Geo.

1/2 Exhaust MCM now full MCM

TDC

 

Not sure which big bore kit you are using..
At any rate, a BB kit with MCM is gonna be a very exciting ride.

Do the "after MCM pre-start checks" I have outlined in my posts on the MCM.
1. With spark plug removed, turn engine over by hand using the flywheel nut and a socket wrench. If there are no problems detected/heard, move on to #2.
2. With spark plug removed, turn engine over with the starter. If no problems are detected, move on to #3.
3. Assuming the carb is functioning correctly, and without touching the throttle, start engine to idle. If no problems detected, all should be "good to go"..

However, your carb must be set up correctly before you rev the engine or ride the bike.
As for carb parts - For near sea level altitudes, you will need a #40 pilot jet, a DJ150 main jet, and a stock slide spring.

The carb must be TOTALLY disassembled.
If the slide lift port has been drilled oversize, you must restore it to stock.

Once all pilot system passageways and parts, and primary fueling passageways and parts, have been cleaned and all passageways tested for proper function with compressed air or spray, you are ready to reassemble and check float level with the clear-tube method.
Set idle fuel screw to 2 turns out from a light seating, start engine to idle, let it warm up completely, set fuel screw to halfway between idle drops.
You will do the above over and over until you get it done correctly - doing it right the first time may take hours, but doing it over and over takes days.
You are now ready to rumble..

 

Once again a big thanks for the pointer and the tips, Carb will most probably be a weekend job.

Cheers Geo.