Ghost rev's - can't fix??

[unit_mx]

Hey
I stuck on my new carb today , a mikuni vm24-ss from a kx65 with the nob style choke and it started up ok but continue's to rev to the moon despite any changes in the idle setting. I have checked the thorttle cable , check the slide , check the throttle and changed up rev boxes but it still continues to rev its tits off. The scenerio is that its a bitch to start now , Im putting that down to the valves so im getting them checked soon but when it starts it idles ok , a little high despite any adjustment on the idle screw ( if you wind it right off it dies obviously) then you give it some throttle it returns to idle and then almost dies before you give it another squirt then it returns and starts to rev and valve bounce.

My set up is:
- Mikuni VM24-SS
- Trail bikes rev box and kitaco adaptor
- Uni filter
- 1/4 nhrc throttle and kitaco throttle cable
- And a ported manifold with mainifold falnge adaptor
So it aint nothing to do with the quiality of the components.

Its on a 140cc by the way

Also where are the air screws on the vm24's , I cant see any screw besides the idle? Im aware it doesn't or wont have a fuel mixture screw but 2 stroke carbs normally have atleast a air screw.

I've tried playing with the eclip position on the needle but nothing. I suspected maybe it was too lean as it runs better with the choke on but just dies when you crack the throttle after about 1/2 throttle.

Also there is a huge lack of power in first gear , and a serious bog and backfire after you give it some throttle
Can any one help me out?

 

[ducar.r.spec]

i think ull find it will be jetted way way way too high

 

[unit_mx]

high as in way too rich?
I noticed it was carboning up the plugs very quickly , like the plug would be covered just from a squirt up the driveway hence far too rich.

 

[tubes380]

it wont run right till you change the internals, the 2 stroke have different internals to the 4 stroke carbys, something to do with a emulator the thing the main jet screws into, and a couple other things

 

[Cactus Jack]

That's a perforated emulsion tube aka needle jet ... A perforated tube mixes air with the fuel better (emulsifies it) at lower vacuum and velocity so that the fuel atomises into the air much better ...

MX 2 strokes are supercharged when the expansion chamber comes on the pipe so they need a greater difference between the idle / low running circuits and the mid and top end jets than a 4 stroke does ... Also I've read where 2 strokes require a dual tapered (dual staged) needle ... whereas 4 stroke needles are more linear and straighter due to the more consistent and steady increase in cc capacity burnt per minute ... ie a KX60 will run like a 60 down low ... then run like a 200 cc 4 stroke up top (which accounts for their "powerband") ... so they need the fuel delivery of a 60 cc two stroke down low and that of a 200 cc engine up top ... (a 140 cc 4 stroke can't handle that much fuel) ...

Supercharging via the expansion chamber multiplies the cc's of air burnt in the cylinder on each power stroke just as a turbo charger would in a turbo'd car versus a stocker of the same capacity ... Yet at idle , both the turbo'd and stock engine would require the same jetting ...

2 strokes ALSO have crank case reed valve induction which blocks reversion flow and uses the down stroke of the piston to force mixed fuel charge up thru the transfer ports and into the cylinder ... the spinning crank churns the charge up and keeps it highly atomised ... plus they also induct fuel/air at twice the frequency of a 4 stroke ... so they need and can get away with bigger pilot jet ...

Anyway UNIT ... What's the follow up to this story ... DID you get the VM24-SS to work properly on your 140 ?????