ScootDawg Forums - View Single Post - just installed a 80cc big bore kit and want more speed

blueboy5000 · 08-12-2015, 07:26 AM

Having installed literally dozens of bbks on 139, 1p40, 157 and 152 engines, as well as being extensively familiar with all makes of scooters since I built my first Lambretta in 1988, I will now state that achievement of any flat land speed of over 5Omph on a 73cc 139, is pretty good, and about all it will do.

Mods help the 139 gain acceleration, but really don't do anything to the top end. A 73cc engine is approximately 4cid, or 1/3 the displacement of the cheapest lawnmower available at Wal-mart.

To assert the modified 139 is capable of speeds in excess of 55 mph on flat ground, is untrue, and unrealistic.

08-12-2015, 07:26 AM	#6
blueboy5000 Join Date: Jul 2011 Location: Connecticut Posts: 493	Having installed literally dozens of bbks on 139, 1p40, 157 and 152 engines, as well as being extensively familiar with all makes of scooters since I built my first Lambretta in 1988, I will now state that achievement of any flat land speed of over 5Omph on a 73cc 139, is pretty good, and about all it will do. Mods help the 139 gain acceleration, but really don't do anything to the top end. A 73cc engine is approximately 4cid, or 1/3 the displacement of the cheapest lawnmower available at Wal-mart. To assert the modified 139 is capable of speeds in excess of 55 mph on flat ground, is untrue, and unrealistic. __________________ 2011 Roketa MC-23-150 4T 150cc 157 qmj 24mm carb w 115 main jet and paper cone air filter Manual petcock w Tygon fuel lines Scrappy Dog Scooters Retro-slash stainless straight-thru exhaust RED spring clutch Adjustable CDI (brand unknown, it's blue and red and works great!) KOSO high performance variator w 12g sliders Gates Powerlink 835-20-30 belt GPS verified 65mph on flats.
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