Right now I am without a camera, but pretty soon I hope to post some pics. In the meantime, I will try to describe my setup. I originally had my engine set over the rear wheel, so the shaft (with a small pully on it) would lower onto the tire....I think friction drive is the term? Long story short, I wanted a mid frame mount and a centrifugal clutch so I could go slower, and I wanted the engine turned around so it exhaused out the left side, since I have a sidecar on the right. I did not want a high top end for this contraption, because I will be using it in crowds of people at Burningman, and need good control at low speeds. So I mounted the engine mid frame and put on a centrifugal clutch. The clutch is connected by belt to a jackshaft (3" pully to 1.75" pully). The jackshaft is mounted below and behind the seat so that it pushes against the rear tire and a acts as a friction drive. I can vary the position of the jackshaft against the tire so I can change the gearing by putting different diameter drive spindles on the jackshaft (and also change the pulley on the jackshaft). On the test run, I had the 5/8" shaft directly against the 26" wheel. The one time I got it moving without killing the engine, it went about 10-15 mph, more or less what I calculated based on a 7000 RPM top speed on the motor. So this gets me in the proper gearing range without adding some kind of a transmission. The only negative is that when I pedel the bike, it also turns the jackshaft and belt, which does add a noticible drag. It would not work well on the street, but is acceptable for the application I want it for.
Now here is one more detail...because I wanted the engine exhausting to the left, I have to flip the drive belt between the clutch pulley and jackshaft pulley so it will drive the bike forward. It's shaped like an infinity sign. I know it sounds wierd, but it did actually work. Thats is why I got a pulley clutch, and not a chain clutch, so I could flip the belt. In the long run, I will add an idler wheel at the middle of the belt so it does not rub together.
So anyway, back to my clutch question....the clutch I had is riveted together, so there is no way to get to the springs without drilling rivits, and maybe not getting it back together at all. So I am considering getting a new clutch....which is why I'm trying to figure out if it is a design flaw, and not the clutch, causing the problem.
Adding to my dismay, I just looked up some general info about small 2 strokes, and found that they idle at roughly 1000 to 1800 RPM ( I had assumed it was much lower than that), while these go cart clutches engage about 1800 to 2000 RPM, So it may indeed be that the clutch is OK, but I need to find one that will allow me to change springs, or otherwise adjust the engagement RPM so its high enough to keep the engine from bogging down.