So i'm looking into doing a 90 cubic inch upgrade on my 2012 forty eight, my question is, what else should i do to it i.e. heads, cams.
I already have Short shots and a stage 1 intake.

 

Where do you find the upgrade? I would like to do something like that in a few months


Most likely next winter....

 

If you do a 90" engine iyou need to do heads and cams. You need some good sized cams and good headwork to take advantage of the extra cubic inches. Because if not, a hot running 1200 will be faster. Check out hammer performance or zippers performance, both places have good reps for 88 or 90 inch sporty engines. If you do most of the work yourself, you will still be in the 5 grand range, if you dont do any work, hold on to your pants cause it will get spendy.

 

The complete engine has to come out of frame, then completely tore down to bare bones, that includes primary and tranny and crank removed. Having a manual and a good selection of tools is very handy. When you put everything back together, tq specs and locktite are a must.

 

and the cases have to be bored.

Power for $, I think you're further ahead with a hot 1250 kit.

 

I have a Axtell big bore in my bike and it is not easy or cheap. The guy that built the bike did polishing and traded his service for the motor work, ended up polishing two motors completely a job he charges 1500/ to do.
As stated you are looking at a complete removal with heavy machine work, new cams are a must and you will want to have the heads reworked, at this point it is all in. Lifters, higher compression pistons (maybe), your carb will have to be setup and if it's FI more money.
My bike was done several years ago by the PO and if it were me I would not go this route today. The guys at Hammer are doing pretty much the same hp out of a 1250 (very impressive) there are Dino sheets on the forum if you search.
Are you using it as a driver, bar hopper, strip bike, resale value and reliability will all be things you will have to consider whichever route you take it will be a rocket, get ready to hang the duck on.
Cheers

 

For the price of building from scratch a 90 incher you can probably get an S&S 100".

Bwana

 

The S&S 100" only fits pre-2004 Sportsters.
Probably too much power for the rubber mount.

 

If you are serious about this, ditch your short shots and use a good 2-1. You will put a lot of money into this engine, so get the best out of it!

It seems likely you are going to use an aftermarket kit, so what brand are you planning to use and what do they recommend for completing the conversion?