Look up the zs190 reviews or the swap page on Facebook and you will see tons of issues on the 5 speed model, shift arm popping off and alot of busted gears. Thats not even getting into the electric start and kicker issues. The 4 speed is the way to go unless you only ride street. They do have 2 different 4 speeds, a close ratio and a wide ratio, so see if the 4 speed your looking at is the wider ratio model

 

Shift arm popping off the detent has been corrected, both at the factory and/or with Ooracing parts; Electric start and kick start issues causing starter chain to break is the result of riders not kicking it properly, opening the throttle while starting, and having too low an idle speed, as well as not inspecting the spring tension on the cam decomp. Busted gears often comes from abusive and aggressive riding styles.

For street use, the e-start 5spd is just fine. If the engine was going to be raced, or pushed pretty hard with clutchless shifts or slamming gears, then the 4spd for sure is stronger. But "stronger" doesn't automatically mean the 5spd versions are de facto "weak", just weakER than the 4spd. But again, depending on the way it's ran, that may be fine, or it may be a problem.

 

Just signed up here today but looks like I get to chime in right off the bat. So I just ordered a Pitster Pro FSE190r 14x17 from TBolt and they called me to ask if I wanted it in a 5speed with electric/kick start or a 4speed with kick only and they are black frames now not red.