what kinda of speeds would you guess of a predator 212 bike with governor removed? 70mph then???
Very simplified:
55-60 but it gets there WAY faster than a chinagirl. Valves begin floating around 4500 but doesn't hit full on valve float until around 5k when new. As it gets miles and the springs wear, it acts as a limiter and starts dropping down to 4900, 4800, etc. No internal gearing means that even with all that TQ, you are kind of limited in gearing choice so you need to run a proper jackshaft or tq converter.
Very different motors...10k+ rpms from 70cc can get nice top end, but will still be slow from a dig. A 212 is a monster from a dig, but the low rpm limits your top speed until you start spending money on cam, port work, valvesprings, etc. Can't just go tiny rear sprocket because then you get clutch chatter and surging down low and can ruin parts.
Many people do it but I wouldn't remove the gov without at minimum billet flywheel and HD valvesprings. We're talking like $120 for not only more performance and 6-6500rpm capability, but also safety - a flywheel letting go at 5,000rpm is moving at over 150mph and can literally kill you. Now I think they are bolted in, but on older clones the timing magnet would launch out of the flywheel as well.
If it will see over 5-6k often than I would change the rod too for insurance...starts getting expensive pretty quickly.
For 212 and up 4stroke info I would skip the motorized bicycle pages and look at gokart performance sites. They have been using and abusing those motors for YEARS before the MB guys started and know all of their pros and cons inside and out.