More crazy Benelli M50 woes  By  beerkeg (Read 1,854 times)

I believe the Benelli M50 is a two-stroke engine. If it suddenly stopped and then started again after a few minutes, it sounds like you had a soft seize. The engine overheated and the cylinder/piston/rings expanded until they seized up. After cooling down for a few minutes you were able to restart. You might have caused some damage to the piston rings and some scoring to the cylinder walls.

But I guess if you are going to install a BBK, these parts will be replaced anyway. Proper jetting is very critical for a two-stroke engine to prevent overheating, especially after a BBK is installed. Most people don't, but I would recommend adjusting the oil pump for more flow when upgrading to a BBK. You need to know that the Benelli brand is a Chinese made scooter, even though it is marketed as an upscale brand. Plain and simple the cylinder, piston, piston rings and cylinder head will be made of a lower quality metal that is softer and more prone to a soft seizure. Installing a quality BBK kit can help, but the engine casings and crankshaft will still be made out of inferior metal. The oil pump will be a cheapo without a way to adjust, but you can replace it with a much higher quality Mikuni that is adjustable. Or you can simply add an extra ounce of two-stroke oil to every full tank of fuel, but that's a pain.

These glorified Benelli M50's usually sell for $1500-$1600, I hope you got yours for a cheaper price. A Kymco Agility 125 is much higher quality, has more performance than a typical 72cc BBK two-stroke, and has much better fuel economy for $1800. The only advantage I can see for a 49cc is operating in one of the few states that don't require tags or insurance, but the usually have a moped speed cap of 30-35mph. I rode both a stock Yamaha C3 and a SYM DD50 legally unregistered in New Mexico, but I was always wary of getting a ticket because both would top out close to 45 mph.

It's not my intention to bash your Benelli M50, just letting you know what to expect. Good luck, I hope my info was helpful.

Benelli was bought out by Qianjiang of China. The M50 is Chinese designed and manufactured. As part of the buyout deal Q.J. kept the factory in Presaro Italy and the employees. But make no mistake about it, the glory days of Italian Benelli motorcycles are no more, and the M50 is produced with Chinese parts.

The Aprilia SR 50 is an awesome machine, one of the best 50cc machines ever made in my opinion. But it is liquid-cooled and uses direct injection. The Minarelli or lesser known Franco Morini 2-stroke 49cc engines produce around 5 HP stock when tuned properly without restrictions. A typical Taiwanese 4-stroke 125cc scooter makes 8.5 - 9.5 horsepower.

Obviously if your SR 50 hits 63 mph, it isn't stock. But I'll take you on with my stock Tomos Nitro 150. It has about 10.5 horsepower and weighs 236 lbs. I did put in some Dr. Pulley sliders, and it's pretty quick to 50 mph. But you would have to mod a lot more to beat my former HD 200 EVO. Exhaust pipe and mild intake mods, it reached an actual 80 mph and could match my Suzuki TU250X in a 10 - 60 mph roll on.

I replaced the 40 idle jet with a 45 and it starts and idles much better with a BBK as before it would stall or idle too high and had to adjust as the temps changed . I have ran a 120 MJ with BBK , pipe and Uni and it seems to like a 105 MJ too.

Most use Mikuni VM 11/22 main jets like here www.scrappydogscooters.com/50cc_2stroke_Performance.html or at www.power-barn.com