I am new to this whole word, I recently bought a 2010 883 Iron and I am still learning about the v-twin and I have a few questions I would like to have answered. 1. Can you run a "1200 kit" (wiseco pistons and jugs) on stock 883 heads? 2. These 90" kits that say they require "case boring." is this referring to the crank case? And if so why must it be bored? I am sure these are some pretty dumb questions but I am 19 with some car knowledge but eager to learn about bikes but the area I am from doesn't offer much. Thank you for your time!

 

Hi from the UK and welcome to HDF. I suggest you use 'search' in the blue bar above and enter '1250', when you will get plenty of recent threads about converting 883s. There are popular kits for 1200cc, 1250cc and even 90". A 90" conversion requires removal of the engine from the frame and a complete strip down to machine the crankcase mouths, then rebuild.

There are 1200 and 1250 kits that can be used with the stock 883 heads and that is a popular upgrade in here, which is why I suggested the search, as you will learn a lot from looking through recent threads. One of them by Mich shows with photographs what it involves.

The 883 has the same stroke as a 1200, but smaller diameter cylinders. 1200 or 1250 cylinders will fit the stock 883 crankcases without any other modifications. The kits come with higher compression ratio pistons, so the increased performance comes from greater capacity, plus more CR. In addition to the kit you refer to look at Hammer Performance, NRHS, S&S and there are others, so look around before settling on one brand.

Hope that helps!

 

For a 90", you bore the cases to allow for piston skirt clearance with the longer stroke.
883 heads are fine with a 1200, but you have to use reverse dome (dished) pistons to allow for valve clearance. Pretty much all the 883-1200 kits have reverse dome pistons, unless the kit comes with new heads, too. Whatever the kit contains, I would expect the kit to contain compatible components. 883 heads can be "worked" for better performance.
A very basic 1200 conversion kit consists of new pistons, rings, cylinders, and a top-end gasket kit.

 

These guys can answer any question you could think of on the subject.
http://www.nrhsperformance.com/

grbrown and HarleyScuba spoke the truth though of course.