Originally Posted by old's'cool

So, I got this NOS set of subject SIS shift levers off Ebay, that exactly match the Velobase description, appearance-wise.
I figured something was odd already when I mounted them, and tested the RD lever before hooking it up; it had only 4 noticable detents. I went ahead and hooked it up, with Shimano compatible cable & housing, BTW. Rear cluster is a 6-spd Uniglide, and RD is mid-80s SIS compatible Shimano 600. I found that, whether in SIS mode or friction mode, that the maximum range I could get was 4 out of 6 cogs. As a check, I changed the RD to a SIS compatible Exage, with the same result.
So, as the next step, I changed the lever to a downtube 6-sp Exage lever I had in my spare parts bin. This lever can shift the full 6 cog range, in friction or index; however, I have not been able to adjust it to index well over the whole range.
The question, and the point of this thread is, what is up with the SL-BS50 lever that I have? Next question is, how difficult would it be to take the guts out of the Exage shift lever, and put them in the bar-con, and would that be the entire solution, or the pull radius of the bar-con shifter going to hang me up? Based on my research prior to purchasing, the SL-BS50 is supposed to pull 6 or 7 speeds, so I'm very puzzled as to why the lever I have cannot pull even 5.