Motorcycle Repair: Cagiva Freccia C12R Lucky Explorer sp125, yamaha tz, suzuki rg

Question
I have a 1990 Cagiva Freccia C12R Lucky Explorer 125sp fitted with 37 Delorto carb as standard, I have a problem with the bike that when i try to run at 4500 rpm - 5500 rpm in 3rd gear the bike chugs but when i throttle on it is ok, ive changed the spark plug and cleaned out the carb thoroughly.The bike starts great and runs great but just wont cruise at those rpm at about 5o kph without becomming jumpy? any idea's?
Many thanks

Answer
Hi Brian,

That's a cool MC!! You have Yamaha TZ's and Suzuki RG's there?

I don't have any experience with this model, but I suspect there's a tuning issue with the carburetor's mid-range.

Send me an email address. I'll return numerous carb information files that may assist you with cleaning and tuning.

My email addy is: mshively1@woh.rr.com

Respectfully,
Mark Shively