what big bore kit can i put on my 1990 fxstc without having to modifying anything. say maybe a 90 would work maybe.

 

You can get an 89 ci kit without having to bore the cases. Anything bigger and the cases have to be machined to fit the new required cylinders. Good luck on your project.

 

McSarge ,atleast be good enough to till where you got it. S&S has to bore the case ,most do and thats for a 88" evo.

 

yeah MCSarge where did you get the 89 kit.

 

S&S - they have stroker kit 89" for Evo.

 

Kamil ,Thats not a bolt on now is it. If the guy don't want to bore the cases, i don't think he wants to break it to pieces. But then if he does ,,do the big bore ,flow the heads too and have a nice motor but by then just buy one of the bigger 100 + ultima engines.

 

Apples and oranges. The question was about big bore kits that do not require boring. Stroker kits are different. Revolution Performance makes an 85" bolt on big bore kit, no case mods required. You want more, machine the cases.

 

I know that with S&S crank you have to split cases. But no boring is neccesery (as I known).

 

thats the kit i found, the 85. $1,000.00. wonder what kind of power increase i would get going from 80-85. would it be worth it.

 

Hotrod351 IF your motor is in real good shape to begine with spend the money to add just a can like a ev23 or 27,air kit and slipons with ingntion and pick up 15hp+ and knot have to pull anythin major on the motor don't have to do something big. Thats a half days work and you can do atlest part of it, for around 1300 to 1450 Doing anything to get your 90 cubic inches is modifying your motor. Look at ultima engines then.
What are you looking to get out of just a cylinder change . Not much with out other changes too. Talk about what you excect and what you have to spend. That will help people to guess better. keep adding the idems below.
80 to 85 alone will make more tq, maybe 5 or 6lbs and 3 or 4 hp with out doing something to help fill the cylinders, maybe just a bit better than just the air kit and slipons. Not worth it by it self.
KW slipons airkit ,carb jetted around 62 to 64 hp Do it your self 450 + Find the mufflers and airkit on ebay and save maybe 50%
Add ev27cam and ignition 70 to 72 hp 850 if shop does the work
flow the heads and thin head gasket 78 to 80. 400 to 600
96 Strocker more cam 90+hp 1200 = labor
Add big bore 100" to 107" 110hp+ add more cam and more head work
These numbers might not be spot on but in the ball park. Start look'n at motors ultima,the driveline company.revtec..3000 to 5600 bucks.
Just be reallistic about what you think you want and talk to of locals at bike night. Talk to some about what they did or would do different. My last bike had 115+ hp and this one i have now has 70hp on a good run and i am tickled with it. FXR with mufflers airkit and old mikuni i had and a ev23 cam and compufire ignition. If this motr grenades on me i will probably by a 100" ultima for as low as 3000 dollars. Can't build one for near that any more.