As a former bike racer, I'm always concerned about the weight of the bike itself. Last summer I got a narrow motor sprocket and a narrow 410 BMX chain on ebay, and recently installed them on the new Schwinn Traveller build. Even the guy I got them from on ebay said he didn't recommend them and that they could be tricky, but as an experienced bike mechanic and with the lightweight Traveller going together I decided to try them on that.
The weight difference didn't seem much when I had both chains in my hands, but I stilll thought I'd try the narrow, mostly then hoping to get a more natural pedal action with the motor off and clutch in.
I got it together just before the cold snap and went outside to test, but the motor sprocket loosened up right away while I was trying to pedal start.
So I just got it out again today. The allignment seemed perfect really, and I had put a half-link in the 410 chain so the tension seemed really good too. The motor turned over in several attempts, but just about the time I started t get it rolling, it threw the chain off, both front and back, and locked the wheel until I skidded to a stop- I still don't realy know why, but
Glad I wasn't going any faster!
Anyway, I'm going to put the kit sprocket and chain back on- the actual weight of the chain is not very much and the larger clearances give a much larger margin of error-
I don't want to mess with something fussy, and I'm sorry I wasted my time even trying the narrow chain. If the kit manufacturers themselves have made the general switch these past few years, there must be a reason. I thought I might be able to get by with it, but my advice is:
Don't spend any extra money, or time, on a narrow sprocket or chain.