Best Performance With 1250 Big Bore kit?
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,114
Likes: 7,638
From: Poolville
Is the 1250 worth the extra money?
A 1250 is about 4% more displacement than a 1200. Assuming displacement is limiting the power of the motor, 4% more displacement would yield 4% more power. In reality, it generally comes out a little more than that, on the order of 6-7%, because there's an increase in compression that comes with it when comparing to a stock 1200. Also, the larger bore unshrouds the valves a bit more and enhances breathing.
So is 6-7% more power worth the cost of the kit? On an otherwise stock 1200, probably not. You can find more power than that with simple pipe and air cleaner changes. But once you've picked all the low hanging fruit, you'll quickly find that additional horsepower starts getting very expensive. At that point, a 1250 kit will be the cheapest horsepower you can buy.
On an 883 that's being converted, though, the picture is quite a bit different. The incremental cost of the 1250 kit over a 1200 conversion kit is only a couple hundred dollars or less. That makes the decision quite a bit easier. Toss in the fact that Sledge Hammer cylinders and pistons are much higher quality pieces than the stock type conversion pieces and it becomes a no-brainer.
FYI: Its quoted because I didnt write it, but I feel its great information about a 1250/1275 set up over a standard 1200
A 1250 is about 4% more displacement than a 1200. Assuming displacement is limiting the power of the motor, 4% more displacement would yield 4% more power. In reality, it generally comes out a little more than that, on the order of 6-7%, because there's an increase in compression that comes with it when comparing to a stock 1200. Also, the larger bore unshrouds the valves a bit more and enhances breathing.
So is 6-7% more power worth the cost of the kit? On an otherwise stock 1200, probably not. You can find more power than that with simple pipe and air cleaner changes. But once you've picked all the low hanging fruit, you'll quickly find that additional horsepower starts getting very expensive. At that point, a 1250 kit will be the cheapest horsepower you can buy.
On an 883 that's being converted, though, the picture is quite a bit different. The incremental cost of the 1250 kit over a 1200 conversion kit is only a couple hundred dollars or less. That makes the decision quite a bit easier. Toss in the fact that Sledge Hammer cylinders and pistons are much higher quality pieces than the stock type conversion pieces and it becomes a no-brainer.
FYI: Its quoted because I didnt write it, but I feel its great information about a 1250/1275 set up over a standard 1200
Grand HDF Member
Joined: Dec 2012
Posts: 3,782
Likes: 1,202
From: river
You you definitely have some valid points there and I'm not going to knock them, 6 7% 12 to 1250 yes I agree and there's other ways of getting that. Now your talking like a true supporter of where performance goes and we all understand that there's different ways of getting performance. There's also other shops out there that can get you the same outcome. Some of us do foolishly spend to get that to 3% cuz you know it does make a difference but we're in all honesty bragging. Been there done that but I still enjoy what I had and it doesn't matter what I spend to get there I still love it.
Just to be clear, not my points, I didnt write the paragraph, but I firmly agree.
Grand HDF Member
Joined: Dec 2012
Posts: 3,782
Likes: 1,202
From: river
There's also other shops out there that can get you the same outcome
I base my knowledge a pinch on dyno sheets and a lot more on street legal “Hot street” xl’s at the drag strip. Anyhow, again, cheers mate!
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