I recently tripped over this forum while looking for parts for my old Sachs and have some info that might be of interest.
My very tired Sachs had bad wear in the crankcase where to axle goes through. i hesitantly took it to rotary's factory at andrews(qld) as i was passing through. Instead of 'palm me off' as i expected (because i have a Sachs) they pointed out some benefits of keeping my crankcase when they could have sold me a new rotary case.
They machined a different axle sleeve to allow for the wear, and even though it cost a bit, it was still cheaper than a new case. i was lucky enough to show up when they were testing my motor.
I asked can they tell me how much power it has? and the main guy (dave i think) who seems to be more than a bicycle mechanic said he can give a ball park but proper standards testing is much more time consuming, he said the most relevent standard is 'sae J13'.. something..something? it went over my head.
From what i could see (it was in a booth) the tester was rather simple other than it had some unusual sensors & wires, that seemed to measure 'frame twist' amongst other things, they pointed out power is checked at the rim (not the tyre), because thats the only place you can check output and he quoted sae.... whatever again.
My motor s maximum output was as 426Watts at 185 rpm with 22nm of torque. they said the official test would be close but offers an adjusted figure for air pressure & temperature?(and the official test would cost $3000!)
I asked how do i remove the governor, and they said there basically isn't any, but if i de-chrome the bore and modify the ports & piston it might benefit with other mods. He said the efficiency of both motors is deliberatly poor by case design, but the rotary is worse with ports cast different to meet 200w output required with no governor. He said even if i did heaps of carb & ignition mods, the ports still let it down and stop it from revving.
Now i know why my sachs is faster than my rotary friends!! i generally get 29Km/h top speed with good hill climb at this speed.
Before posting this i rang dave & told him i was going to, and would he be interested in answering any questions because i'm sure he can, he was a little brief and i was a little disappointed with his reply, he said something like " i'd have to give an engineering lesson to everyone, along with asking them to obtain a copy of sae...bla bla and read it first, then we are all on the same level to discuss".
He said he will check the forum when he has time, and he'll post atech document on rotarys website which he gave me a copy of, it kind of makes sense.
PS my sachs is still faster than rotary & runs better than ever!