Standard carb for malossi 210?

I have a 210 malossi kit on my scoot with a taffspeed exhaust. I am having difficulty getting it to run rich enough and have so far had to put foam air filter on the carb box and a 138 main jet. This is only way to stop a flat spot that occurs when rolling on the throttle at around 60 - 70 mph and plug is a light chocolate colour. I have checked carb base for warping and replaced gaskets. I want to keep standard carb and oil injection but is a big carb my only answer???  Help please. 

take carb off and carb box off clean and new gaskets with sealant, screw for carb box tight carb bolts finger tight on allen key then 1/4 of a turn to nip down petrol/air mixture screw 2-2 1/2 turns out, T5 slide( yes T5 slide will run a touch richer and fuller on the throttle and will help with the drop at 60-70), 128 main, standard air filter with no holes above jets a good starting point to plug chop....good luck

Use the P/PX 200 air filter. This filter chokes the carb a little at high speed and creates the needed fuel progression that this carb would not have otherwise. remember this carb do not have a needle and progression over half-throttle would not work well without the PX filter.

The T5 SI 24/24G carb and filter has the bigger T5 filter wich does not create this condition and is VERY VERY VERY hard to set up for this reason.

Avoid the use of SI carbs without its filter You need it for prigression. You also need it becaise it catches the gas that the engine splits up out of the carb under sudden acceleration, and then enriches the mixture for a more powerful pick up.

Look at the COSA. They have a much better foam air filter inside the frame but they still use the PX filter. Now you know why.  

  

p.s. I would bin the autolube.

If you want this carb to work:

1st. Remove the gas filter from the carb's bowl cup. That alone increases the flow to the float bowl by    20%

2nd Replace the carb bowl cap cover and needle for the cosa 200 model. The cosa 200 needle is wider and has a better gas flow

3.On the cosa bowl cap drill this hole: http://picasaweb.google.com/Vespisti1/VariousPXPics#5311184238492565714

to 2.3mms (use imperial -inches- size equivalent). Drill it from top to bottom so you don't damage the needle's seat  

4.pass a dril bit of 1.9mm (use the imperial equivalent) to this hole

http://picasaweb.google.com/Vespisti1/VariousPXPics#5321937225842472546

 

The problem of the SI is gas flow. This mods take care of it.

If you need a main jet over 128 -130 you have insuficient gas flow due to the design limitations of the carb body.  For instance: The hole shown in the second picture is the one that takes the fuel from the carburator bowl to BOTH jets. It's width size is 1.6mms or "160" in tems of the SI jet sizes. Besides, it is like 15mm long. That is the reason why it restricts the fuel supply to the jets.

 Note1 : Don't do mod number 4 if you dont do numbers 2 & 3 first or your gas bowl can dry out at speed.

Note2 : Once you do number 4 you will need to down jet 5 to 10 sizes dependig on were you started. Y went from 135 to 125 after I made this last mod.

 

Thaks a lot mate.

The most popular option via thw Taffspeed shop for touring tune 210's was Malossi 210 with Goldline mk 4 and a standard upjetted carb. All bikes are slightly different but routine settings were approx 170 air jet, be3 atomiser 125 -128 main jet [sometimes 130 but not very often]. Standard P2 air filter. 18 degree timing. Sounds to me like you have an air leak somewhere if you need a 138 main jet.