Mbk mach running problem

This is usually a fuel problem. The bike is running either too lean or too rich. Check your spark plugs -- if there's black carbon on the tips, the fuel/air mixture is too rich and needs to be leaned out. If they're white, it's running too lean. If they're tan, there's some other issue. Clean or replace the air filters and check your inline fuel filter (if you have one) to make sure there are not clogs or obstructions.

may be due to dust in your throttle body, spark plugs
1 - Try a throttle body/air control valve
2- check if by removing plugs from the spark plugs there's any change (no change in engine vibrations means a dead spark plug) you may wanna do this while the engine is hot

ck battery charging condition
make sure cables are tight
ck volt reg

Hi,,,yes i would fit new plugs,,with all the missfires before you replaced the reg/rec you are sure to have some fouled plugs,

i have experienced this many times,fit some new plugs.

Could be a number of things....but sounds like it might be fuel starvation. Check your fuel filter and maybe replace it. Check and make sure there is fuel flowing to the carb. After that you would have to service the carb.

I am not completely positive that this is your problem but one thing to try when it starts cutting out is to loosen the fuel cap. On a lot of 2000 through 2004 Harleys the vent in the fuel cap gets plugged up and creates a vacuum not allowing the fuel to flow to the carbs. If this doesn't help run the trouble codes to see if there is a ECM related problem. To access the codes, turn the ignition on for about 3 seconds (one second after the fuel pump stops running) and then turn the ignition off for 3 seconds. Repeat this, then turn the ignition on and the codes will flash on the check engine light after about 8 seconds. The first series of flashes (about 3 flashes per second) are intermission flashes then there will be a 2 second delay and the first code will flash. If the first digit of the code is 1 the light will flash one time and then there will be a 2 second pause before the second digit. There will be a 1 second delay between flashes for a digit of 2 or more. All codes are 2 digit codes. For example, 11 would be throttle position sensor, 12, barometric pressure sensor, 14 engine temperature sensor, 15 intake air temperature sensor, 16 battery voltage, 23 and 32 fuel injector, 24 and 25 ignition coil, 33 fuel pump relay, 52,53,54,55 ECM failure, 56 crank position and cam position sensor timing.
Hope this helps.

Since the bike is new, chances are strong that fuel IS the problem.
Also chances are that the carb is perfectly fine. Since the bike is new I'll bet yoy have washed it several times already. The dealer may have washed it also. Fuel is the problem because bikes do not run well on water.

Drain the carb. Remove the water trap bowl on the bottom of the petcock, (gas valve). Look at the gas in the bowl. Any water in the bottom of the bowl? Drain a cup of gas from the petcock. any water in the cup? I am very hopefull this will fix the problem. With a new bike and a clean carb and fuel system not much else should be wrong.

Make sure that there is no sludge or rust in the fuel tank and that there is good flow to the carburetor. Pull the gas line fron the carburetor and check the flow of fuel. Remove and dismanthe the carburetor. Run a small copper wire through all jets and passages. Make sure that the throttle slide is free and that the enrichment (choke) valve seats properly.

Have you tried checking the float level in the carburettor?
Sounds like your scooter has a fuel starvation problem.