ThatGPzGuy wrote: Looks like Z1 has the 530 front sprockets back in stock.
Yeah. So, a little update. I ended up buying that 18T sprocket from Z1E (what are you gonna do? nobody else has it!).
Put it on a few nights ago. I like it. The chain is a little smoother/quieter going over the larger radius of the front sprocket. The power band feels more appropriately placed. 2.33:1 feels like it's just between 2.20:1 and 2.73:1, which is what I expected 2.47:1 to feel like. Obviously there's a non-linearity there.
I still think the vortex and other sprockets could work. Jeff from Z1 tried to tell me that using spacers would be dangerous because of the reduced contact area with the splines... I told him that the sprocket I needed spacers for was from a ZX1200R, a 175HP bike compared to the KZPs 98HP or so and that I didn't buy that excuse for one second... I still think spacers would work fine, just haven't been able to source any that would fit.
The required dimensions, FYI, are 30mm ID, 38mm OD and 1.5mm thickness (x3). I can find 30mm ID, but only with much larger ODs, which would perhaps rub on the shaft oil seal...
If I had to do it all over again I would have either stayed with the 630 setup or gone with 17T front 530 and a smaller rear sprocket (although I'm still concerned that the chain would hit the swingarm, etc). So realistically, I'd say if you want lower ratios, just stay with 630 so you don't have to rely on finding this rare-ass 18T front sprocket with the boss on it.