MBK Nitro Sport50 cylinder is bogging and cut out. :( help

Helloo, just wondered if anyone could give me some advice.
I have a 2002 Mbk Nitro, which i bought standard and have fitted these parts:
Doppler SF1 50cc Cylinder (Nothing to lairy just slightly bigger ports)
Doppler S3R Exhaust with all the restrictions removed.
I have kept the standard carb and crank, I know a bigger carb may give me better performance but im not too bothered at the moment.
Malossi filter in the standard airbox (Red one)
Polini speed control kit(Belt, variator, rollers and torque springs)
Polini 2g clutch. With the weaker springs in at the moment.

Right, I got it all fitted by my grandad which possibly makes me sound like a fucking nuttaaah, but he worked for a world rally team in the late 80s and early 90s so hes not a complete div. The carb orginally had an 86 jet in it which I first of all replaced with a 92(Better rich than lean was my thinking) I also had 4.9g rollers in which were ok on the standard cylinder so I thought i might just try them on this setup. So the first time i gave it a go it didnt go anywhere and just bogged bag down to below idol. So I fitted the 90 jet which made it sound a lot better but still had the same problem but it bogged less as it got warmer and then managed to slowly pull away and then picked up at about 5 mph. I left it like this believing that its all new and being run in so it will be like this. But I notice that every where I leave it running and even after its stopped it leaves big puddles of thick black oil. Its also fairly smokey, not terrible though. So the first time i took it up to speed it got to 30 and felt like it didnt want to go any further than that and after half a mile it wet the plug and cut out. I personally didnt think that engines could wet plugs while gooing along very easily. I have heard that the rollers need to come down to something in the 3 gram zone anbd that the clutch needs to bite a little higher so the engine has momentum.(At the moment i have the clutch springs adjusted so it bites as low as possible) So I just wondered if this problem appears to be jetting or rollers or clutch? Or even a combination of the 3. I have some 3.6g rollers that i can put on as soon as i have access the the tool and i could put the stiffer clutch springs in as soon as i have acces to the tool.
A shop told me that the aeroxs standard jet is quite large and may even be ok for my setup. I am planning to get hold of an 88 just in case jetting is the problem.

I would love my ped to be completely sorted for my birthday on the 26th of feb which is when I am taking my test. I bought this moped as a project and it was battered and the start but I have put so much time, effort and money into this bike and would just love it to run sweet as a nut! I check this forum daily and how found alot of help with problems without one single post! :cheers:

I hope someone can help me Many thanks, Joe.

 

Right ok, thanks for you reply and advice. I just wanted a confirmation as I have never messed around with an engine before.

Would it be the rollers that wouldnt let it go anywhere past the 25-30 mph mark?
Thanks Joe.

 

alrighhhtttttt, thanks for you advice.