To big bore or not to big bore... That is the question

[jax chaeles]

87 aero 50 (nb 50)

I soft seized my motor so I am required to replace some of the inner workings of the speed demon, what I want to know is if I can simply throw in a BBK and hit the road. Or if I need to do some other mods. It has an arrow exhaust as of now. Otherwise stock.

If I put in a slightly oversized piston it will run me about $150 in parts.

What BBK is the best bang for the buck?

Thanks for the help folks!
Jackson

[Wheelman-111]

Greetings:

The Malossi from RedEftperformance would be my choice. 65ccs. 30 percent more displacement, 50 percent more power. Not too pricey, and basically bolt-on.

[paulpauly7]

go BIG or go home!! lol thats my theory anyway

[tazland001]

Just because you BBK a scooter does not mean it will go faster. For example if you put a 50mm BBK on a elite sr(94-2001 it will not go much faster than stock. Your bottom and mids will improve but the top end is really not that much better.

[jax chaeles]

Can I do a big bore and nothing else? Or do I have to change other parts also?

[kingkamehameha]

Listen man i know alot of people dont like to hear this but when you put a bbk on reduces the reliability of the scooter. My suggestion would be to replace that engine with a stock updated version. A stock 50cc af16e motor or clone kymco/sym motor with minor cvt upgrades and fresh tune up will have superior reliability and fuel economy while giving you a better top speed and take off. That should suit your needs and can push that aero to 50 mph on the stock 50cc dio motor. If later on you decide you want to hot rod the bad boy and throw reliablility and economy out the window, the af16 is the perfect platform to do it on. For now i would just do a quick and simple engine swap and save money for a build down the road. 100 bucks worth of upgrades on the af16 will get you to 50 easy. The same cant be said with the afo5

[kingkamehameha]

Let me re state the ending part. You CAN buy a better variator and mill the head on your afo5 for a compression bump. I have heard claims of people hitting 45-50 on that motor. Its the same as the 87 se50 afo5 with the 10:1 gears stock. You can also buy the malossi bbk but the aftermarket availability for exhaust pipes, cranks and other parts are limited. You can take a few different routes. Hop up the motor you have now and tear a hole in your walet, swap in a newer designed motor, or just try to squeeze a lil more juice from your af05 with the cheap mods i mentioned

[JJ Joseph]

What BBK is the best bang for the buck?

I like a BBK for the extra takeoff and the additional power when going up long hills. They're not expensive (approx $75), but they do need some other extras to get the best bang for the buck. Most BBKs have a bigger 32mm exhaust pipe which means your stock exhaust likely won't fit (add $150 for BBK exhaust). And your carb must be rejetted including the low-speed jet ($15 for jets) . In some cases your stock fan shroud won't fit because the BBK cylinder & head has bigger cooling fins. To get a higher top speed, I installed Athena gears ($50) and run a stock Chinese drive belt ($11). I've had a Ruima 85cc BBX in my Dio for over 10,000 miles with no problems, using the stock oil pump. The BBK is actually designed for a Kymco 9, but fits the Dio/Elite except the spark plug is in a different location so I had to buy a Kymco fan shroud ($40). It's no green machine since it sucks a lot more gas than a stock unit. It cruises in city traffic nicely at 45mph, tops at 50mph. You will reduce reliability with a big carb and expansion pipe since your max RPMs (and speed) will be MUCH higher since a 2-stroke will wind up much higher with carb & pipe, so watch the RPMs and avoid cruising at 12,000rpm! It's fun, but expensive, so keep the RPMs within stock limits (9,000rpm max for long life). That's my 2 cents worth.