nrhsperformance kits

[06 1200]

i'm looking at getting the 1250 cast iron kit with the stage 2 kit, anyone have any info about how much hp to expect or reliability, etc.
i like long rides an to give it hell occasionally so i don't know if i should get the cast iron or the aluminum 1250 kit. i don't want the bike to over heat from te cast iron, but i like the over kill of strength from the cast iron, any input on which route to take? live in temple, ga an plan to take bike to west end cycles in fl to have the work done-closet place that nrhs perfomance could suggest.

hope to get lots of helpful replies thanks

[Jimbos883]

Except the cost factor

[NRHS Sales]

Cost is a big reason. I wish I could sell the all aluminum cylinders for less but I cannot.

But the all cast iron are also the stiiffest and best ring seal cylinders we sell.

[avnsteve]

Originally Posted by NRHS Sales

Cost is a big reason. I wish I could sell the all aluminum cylinders for less but I cannot.

But the all cast iron are also the stiiffest and best ring seal cylinders we sell.

that's why I'd go with cast iron...

[883Cwk]

NRHS has dyno charts on line for the 1250 kit with stage 2 heads.

883Cwk

[sporty58]

There are too many different factors to even guess on your hp will be.
1. what is the rest of the set up?
2. dyno's differ from dyno to dyno and operator to operator so the actual number dosn't mean much other than a baseline to tune from, assuming you use the same dyno/operator every time.
one thing that is sure though, you will get quality parts and more hp than before.

[aswracing]

The 1250 cast iron kit is a very high quality piece that gives great ring seal and long life. It's a hell of a bargain at $750 IMO and makes a compelling case over a 1200 conversion.

The 1250 kit is about 4% more displacement and to the extent that displacement is constraining the power, going 1250 by itself is generally worth about 4% more power.

That said, we generally see more like 5-7%, and the reason is (I believe) is that moving the hot cylinder wall away from the intake valve helps the flow.

If your heads aren't capable of delivering the additional flow needed by the additonal displacement, the 1250 won't bring the expected 5% or so to the party. This is mainly at higher rpm's. In fact, if you look at this dyno sheet, which was done with 883 heads:



Notice the yellow line. That's a 1250 kit on an otherwise bone stock 883; even the stock pipes and air cleaner. Notice how it's strong down low. The breating is not constraining the power at low rpm because we have enough capacity to fill the cylinder. Displacement was constraining the power. Now see what happens as the rpm comes up. Compared to the other charts that allow more breathing, it's nosing over badly. A 1212 would've made just as much power up here as the constraint has moved from displacement to breathing.

The power of the motor is always defined by the part that's holding it back. I think too many people try to look at a motor's output as the result of all the go-fast parts on it. That's not the case at all. The motor's power is defined by whatever piece is holding it back. Working on anything else is a waste of time and money.