bbkit opinions

[benhonda]

I have a taotao 50cc that i turned into a mini bike.  It is fun but acceleration and top end could use some improvement, especially since I weigh 250.

I'm pretty sure I would be happy with the 100cc kits that include aggressive came and larger valves, but I don't want to put over $100 into the bike (kit plus carb & exhaust)

But I see the 80cc kit (just larger jug and piston) are like $35.

And I already have some larger jets I can put in the carb to feed it more fuel.

Just wondering if anyone has such and upgrade and could share the difference it made for them.  Acceleration/pulling power?  How much of an increase to top speed?

[GrumpyUnk]

I cannot answer about 100cc bbk, but the 72cc bbk seems to add more takeoff torque. It actually has a bit of 'grunt' when you open the throttle. A 39mm piston will not allow acceleration while climbing the hill leading from home. A machine with a 47mm piston and cylinder will accelerate, or can, when climbing the hill.
A '100cc' bbk should do even more. At lower engine speeds, you'll have more torque, and actually don't need the flow rate of a larger carburetor. You would need the flow at higher rpms, but if the carb cannot flow, the engine won't know, it will just consume whatever it is fed. You can expect a bit higher top speed, but be careful you aren't revving the beans out of the engine while running fast. Having a tach connected, even temporarily, can be of value when figuring out if things are working properly. If you get consistent and quick pops to high rpm without any increase in speed, that's an indication of the need for CVT investigation, for example. In my case, I figured a bit more variator weight, and finally a new belt, and it made a big difference.
tom

[donaldsonta]

If you're trying to keep it super cheap I'd probably do the 80cc (actually 72), pod filter, drill the muffler, and rejet. That's about $40-45, leaves you plenty of room for a decent belt, tuning weight set, and a set of rollers.

That will probably be a very significant improvement on a stock 49 with unknown rollers, but without getting into a bunch of money.

[milly]

I have used a few super cheap 80cc kits here in the U.K. and find they valves burn out quite quickly in the head and that's with the correct valve clearances. So might be worth lapping in the valves before using. At £24 for a complete bbk can't expect quality that's for sure. Barrel and pistons hold up well. Beat I found is the Naraku products bit more in price but better quality.