This has been discussed in other threads but I will give my 2 cents. #1. You can run a belt, but you would need to run it at almost a 1 to 1 ratio for the jackshaft to spin fast enough for the clutch to work properly on the other side. #2. If you have no reduction on the primary side then the secondary side would need to have a huge reduction to be able to get to the speeds you will need to be running.
On my 2 machines the primary ratio is 2 - 1. So, say the clutch engages at 3400 rpms, and the redline of the engine is 7000. The jackshaft is only spinning 3500 rpms at redline. A 1-1 ratio would have the jackshaft spinning the same rpms as the engine and good luck finding decent bearings to handle that kind of rpm. Secondary ratio varies, but is in the 3 or 4 - 1. Gives final ratios of 6 thru 8 to 1. To get that on one of the drives is a big jump in sprocket sizes. Hope this helps.