Stiletto Jackshaft or Jackshaft+3:1 gearbox?

[Stormsorter]

First a little background story.

I have a Giant Stiletto and I think I finally picked an affordable and more reliable than a ChinaHT engine for it. The Dax GT50 2stroke or the same engine I found cheaper that already has the Stage II or III upgrade kit. The Stiletto has a jackshaft in the form of a standard 3 piece crank bottom bracket were it links 2 chains. This is a large chopper with a 24x3 rear tire.

Now on to the actual question.

I have a few options on how to set this motor up. Both options would go to a standard fixed gear bike sprocket that can range from 17-22 teeth, then to the bikes gears, a Shimano 7 speed hub with Megarange as they call it. Actually I could use two different size sprockets, an example would be 18 on engine side then a 20 on the pedal side that goes to the bikes gears. Currently I have a 20 on the pedal side. I would rather not change that since I can't get it back apart and would cost me about $30 to replace the parts.

Option 1: Use a standard pocket bike gearbox that is just the clutch bell with a 6 tooth sprocket and a housing that bolts to the engine. There may be other size sprockets but I haven't looked that hard yet. This option is cheaper and the one I would prefer to use for a few other reasons.

Option 2: Dax 3:1 gearbox with the option of 11, 14, or 20 tooth sproket.

I am clueless when it comes to gear ratios or I wouldn't bother asking. Actually if I hadn't seen Staton-Inc using a gearbox on the same bike I would have just tried Option 1, since there have been a few ChinaHT builds with no gearbox. After some digging around, the Staton-Inc gearbox that they sell with there Stiletto kit is a 18.75:1 reduction.

Basically, can I run this type of engine without a gearbox or should I use a gearbox and what kind of reduction should the gearbox have if I should run this setup with one?

 

[Stormsorter]

After lots of searching and reading about 200 pages worth of posts I think I found the information I needed. I also learned how to calculate the ratios myself and found the calculator to help me do it faster.

My goal for this build is to be able to take off from a standstill using the motor. A few people on the forums here said that for a standing takeoff with these CAG motors they used a final ratio of about 35:1 (I averaged this from there ratio's).

So to answer my own question, the only easy way to do this would be with the Staton 18.75:1 gearbox. I will not use this box since it mounts mid frame with the engine on the right. It would probably work great but to me it seems like it would just look funny.

Another option I found is a pocket bike CVT. Unfortunately after figuring out how to make it work with the right ratios, I found a dealer that had one but in the description it says "Clutch drum and output sprocket turn in the opposite direction". I also would have had to find a way to mount a 10 tooth sprocket for a standard bike or 415 kit chain to the standard pocket bike 6 spline output shaft.

My third option would be to build my own gearbox but I don't have the tools to do something like that.

So in the end I'm gona just wait and if I'm lucky I'll get the extra money to get the Morini this bike deserves. I can picture it now, a big chopper with an S6-E, 7 gears and disc brakes.

 

[flmotorbikes]

I would build your own gearbox since you can custom make it to
your exact prefercences