I've been pushing around 17hp through a 6" Comet driven with no issues at almost 7,000rpm.
I watched a video the other day that made no sense. A guy did a top speed run with a Juggernaut on his Coleman 200. He got 59 mph at nearly 8000 RPM. Then did another top speed run with the jackshaft and got just over 60 at a little over 8K RPM.
How would he get that kind of RPM with the Juggernaut and a 45 tooth sprocket? Just by the sound of the engine it sounded like the belt never shifted as he screamed up to 59 mph. It was like he was running a 9 or 10/1 ratio the whole run. Even if the final ratio of the Juggernaut is 1/1 in high that kind of RPM should have him over 100 mph with his gearing.
Are these designed for no belt shift if big power is being applied? Why even have one when his jackshaft had nearly the same results?