Well, I thought I was making real progress, but I’m rethinking my idea of moving the swingarm pivot rearward from the rear engine mount. I’m afraid it’s not going to work. Look at this photo:
Look at the distances from the countershaft to the swingarm pivot to the rear sprocket. I’m thinking that the distance between the front sprocket and the swingarm pivot is too much of the total percentage of the sprocket-to-sprocket distance, so that the chain tension is going to change too drastically as the suspension moves. The Bultaco motor already has the countershaft pretty far forward from the rear of the crankcases. By voluntarily increasing it further, I’d just be making an already less-than-ideal situation more unworkable.
Time to rotate my thoughts and take another run at this.