I agree with GRbrown. Just swapping the jugs and pistons and leaving your stock 883 heads will give you a completely different and much more powerful bike. You can always do the heads and cams at a later date if you want. You will need to remap your ECM and new pipes and AC are also important. If you do the work yourself you should be able to do this in the US easily for under $2000. Up here in Canada a 1200 is about $2500 more than an 883 so it is cheaper to do it yourself if you can.

Talk to Dan at NRHS and he will give you the info you need. Lots of people do the conversion and use their stock 883 heads.

 

Just found NRHS's power curves (scroll down a little). As you will see, each stage of headwork really only starts working at around 4,500rpm, where there is already a substantial boost in performance over a stock 883. As my Sporty is really 'ours', I have no plans to do any headwork if and when Mrs B lets me play! I reckon we will both be v happy.

 

I have over 10000kms on my DIY 1250 conversion with stock heads and it is running great and has lots of power. Unfortunately the wet winter weather is here so she is going to be put away until spring.

 

I'm kinda two minds about this one and here is my logic.

Regardless of which way you go, you have to do tuning NO LESS THAN ONCE. If you do it in 2 stages, you have to tune twice. So if you have Powervision and will DIY then it is just time. If you are like me and will get it done on a dyno, it is 2 tuning sessions.

The heads will have to come off regardless of what you do. Again, unless you are going to DIY, you have to pay for for the head to be removed if you do it later

The cams you probably won't have to pay that much more to do since you are already there.

All in all, I am not sure but I think that a person needs to see what they want to do. If there is a hint that you will be adding heads and cams later on, perhaps it might be better to delay that gratification and save up for the stuff so you do it once and do it right. Right being the way you are going to do it in the end. I hate to do it twice but that is me. I have bought cheap before and it ended up being way more expensive than doing it the way I should have the FIRST TIME.

Sure, there are those that will be happy with just the 1250, without the heads and cams but there are also those that will not be happy till they maximize the thing. And then there are those that will never be happy and keep modding and modding till that bike is sporting a GM 350 engine and their wallet is empty and they are selling blood and sperm to make ends meet. We each have to reach in and see what type we are.

 

It was pretty simple, and very beneficial. I didn't have to deal with the fuel injected issues.

 

I'm just saying it is possible to increase the power of your 883 substantially without spending a ton of money and with the possibility of future upgrades if wanted. I planned on doing my heads and cams at a later date but after riding the bike for a year I have decided that it is good the way it is, has lots of power now for the riding I do, it is not dynoed but likely has more power than a stock 1200 according to the NRHS dyno charts. Do a little, do a lot, spend a little, spend a lot, that's the beauty of it, you can do what you want. Obviously if you want to squeeze every HP possible from a sportster engine it is going to cost a lot of money. Even if you buy a 1200 and want to get 90+ HP that is going to cost you a lot more too. After all, these engines are not high hp engines anyways, my old 1984 gs750 which I still have came stock with almost 90 hp and would still kick most sportster's modded or not.

I am not sure that I could make much use of a 90 hp sportster as most of my riding is below 5000 rpm, I ride mainly in the torque band so I don't think I would benefit enough from it. The cheaper route happens to work better for me and my budget.

 

I have a 1250 kit on the way to me from NRHS. Will be using either a PCV or PowerVision.

To the OP, a full tuner is absolutely needed.

I already have the open exhaust and air cleaner.

I will be polishing the 883 heads myself and keeping stock cams and keeping stock 883 gearing.

Cost will be well under $1000 and about 10 hours of my time.

While doing this I will be doing quite a bit of other work to the bike, but once done will be doing a bunch of Dyno runs for comparisons on different configurations that I will post up.

 

No question about that. I just want to make sure that someone doesn't do something and then kick themselves in the butt because they could have gotten a lot more more by going slightly more financially.

As I said, there are pros and cons to everything. To you, doing it bit by bit might fit into your way of things but to somebody else who has won the powerball lottery, well,

I have been bit that way so many times in the past, I have learned to consider my moves very carefully as to what the final goal will be. I would rather warn someone than see them where I have ended up so many times, wishing I had just waited and done a little more or gotten better quality stuff up front instead of trashing an expensive short block.

In my case, the final goal will be the heads, cams for the 1250 so I will save up for them and get it. That is, unless I win the Powerball then all bets are off. At that point, my bike will be waxed by strippers and hookers every week and I will try to hire a hottie for a mechanic. And oh, the bike will be maxed out.

 

Just read DK's post and remembered yours. You WILL need some sort of fuel management. PowerVision seems to be popular and if the wife didn't get me SEPST, I might have gone for it. Either way, I won't be tuning my bike so it isn't that critical. I prefer to have it sent out and done on a dyno. I would check around to see who does what.

For instance, Jamie at Fuelmoto does NOT do SEPST any more so you would have to buy Powervision or at least get a license. I am not too familiar with the other HD shops that have a dyno AND competent people so it might be an issue. Fortunately Jamie has recommended a HD dealership that can do it.

Check with the people around you and see what they offer before you buy. You'd need say SEPST and what the dyno session (assuming you find someone you like) to do it. That or DIY. Not sure how good you feel about DIY but there it is.

 

Will polishing the heads reduce the compression ratio much? Is it as simple as getting one of those porting/polishing kits from a company like Summit and using a deft hand and careful eye?