HarleyTechTalk

I just bought an 02 883 sporty for 1000 bucks off my neighbor.  It's in great shape but not enough power.  A few questions I've been researching is will 04 up XL 1200 heads work on a 1275 kit on that bottom end?  What cams would you recommend for that setup?  Anybody ever hopped up a sporty?  Or if I kept the 883 heads would an 04 up 1275 conversion kit work?  It'd be big fins.  I only ask because I could get that cheap right now.  Thanks all

This should be posted in Sportster section.

Hammer Performance is a vendor here, aswracing a member, they can answer all your questions if you don't get any here.

This is their website, note the first topic line!

https://hammerperf.com/sportster.shtml

As fast as heads go, the adage is, Horsepower is in the Heads! Your 883 heads are not up to the task.

Also, this:

https://harleytechtalk.com/htt/index.php/topic,118230.0.html

Thanks for the replies.  So it looks like the 04 and on heads will work with my lower end.. 

Quote from: Shep236 on April 12, 2024, 05:08:22 PMThanks for the replies.  So it looks like the 04 and on heads will work with my lower end..

The vast, vast majority of 883 to 1200/1250/1275 conversions are done with the stock 883 heads The primary reason for that is cost; a new set of 1200 heads will set you back about a grand. But there's also a power band consideration. Here's a chart you may find useful:



This is the same bike, a 2007 XL883, converted to a 1275 both ways. In blue is a 1275 conversion done with 1200 heads and in red is a 1275 conversion done with the stock 883 heads. The compression ratio is the same, as is everything else: same air cleaner, throttle body, cams (stock W's), exhaust, same dyno, tuned by the same person (yours truly). I tried to keep this a straight comparison between a 1275 conversion done with stock heads vs. a 1275 conversion done with 1200 heads.

As you can see, the 883 heads made more up to about 4600rpm, and then the bigger valves of the 1200 heads takes over and they make more above that. So a big part of the answer here is where in the rpm range you want the power. There are a lot of people who prefer more power on the bottom vs. on the top.

If you decide you want to do it with the 1200 heads, then here's what you need to know. 2004-2006 XL1200 heads will go on, with the addition of a new front bracket - the one that connects the front head to the steering neck area. The bolt spacing on the head is different, but HD has an adapter bracket available, part number 16689-05. Also, check your pushrod lengths on assembly. The later 1200 heads are .020" shorter than your stock heads, which by itself is generally not enough to get you into trouble on pushrod lengths, but if you use thinner head gaskets to tighten up your squish clearance, you could get into trouble. It's dirt simple to check this on assembly and there's no reason not to do it.

2007-2022 (EFI) will also go right on, but in addition to that bracket and the pushrod length consideration, they need a slightly wider intake manifold. Guys who run a regular width intake manifold often have problems with the manifold seals getting sucked into the ports on decel. A wider manifold designed specifically to solve this problem is readily available in the aftermarket.

The best deal in town on 1200 heads is a set of these:



The 16500164 versions come with the adapter bracket and also don't require the wider manifold. They are available in black highlighted only.

The other two flavors are EFI so you need the adapter bracket and wider manifold.

All of these have been milled additionally, so shorter pushrods become a requirement.

Thank you ASW.  How much power do you think this 03 with just the 1275 conversion with stock heads would make?  If it'd be comparable to what you posted I'd be tempted just to do that and be done with it.  I have an electra glide with head work and cams as my go to bike.. this is just gonna be for fun.

You cannot view this attachment.
883/1200 100hp/88ft lbs using HQ cams and their porting on Buell heads with 44CV.
Got 92hp with HQ ported 883 heads & 40CV. When I asked Doug Coffee about using 883 heads, he said it was easier to remove material than add.
This bike was a LOT of fun...

Quote from: Shep236 on April 13, 2024, 10:01:56 AMThank you ASW.  How much power do you think this 03 with just the 1275 conversion with stock heads would make?  If it'd be comparable to what you posted I'd be tempted just to do that and be done with it.  I have an electra glide with head work and cams as my go to bike.. this is just gonna be for fun.

A bone stock EFI 883 makes 47ish horsepower, where a bone stock carb'ed 883 is doing good if it breaks 40hp. This 7ish horsepower advantage to the EFI version remains about the same whether you're comparing stock-to-stock or converted-to-converted. It comes from both the cams difference (W's in the EFI bikes, D's in the carb'ed bikes) and the EFI itself (the 45mm throttle plate and the ability to tune both cylinders individually).

Thanks for the replies.  I ended up scoring a pair of 2017 xl 1200 heads for 300 bucks for the pair.  I'm gonna utilize those along with the 1275 big bore kit, and a hsr42 Mikuni carb.  Just haven't decided on what cams to run with it yet.  Was thinking the andrews n4 or n8s.  Just for ease of use really. 

Quote from: Shep236 on April 16, 2024, 08:05:52 PMThanks for the replies.  I ended up scoring a pair of 2017 xl 1200 heads for 300 bucks for the pair.  I'm gonna utilize those along with the 1275 big bore kit, and a hsr42 Mikuni carb.  Just haven't decided on what cams to run with it yet.  Was thinking the andrews n4 or n8s.  Just for ease of use really.

Either of those cam grinds will work with the 10ish:1 compression ratio you get with stock EFI 1200 heads over a flat top 1275 kit. But keep in mind that both of those are very old cam grinds, designed around the small valves and much inferior 1986-2003 hardware. The later heads have larger valves, 7mm stems, and a factory beehive spring pack, with an entirely different set of capabilities and limitations.

Let me give you an example. The last Buell product to use the old hardware was the 2002 X1 & S3 models. They came from the factory with "B" cams (.497 lift) and a 6800rpm rev limit, and at 6800rpm, the valve train was already starting to lose control, it was really marginal.

The very first HD product to use the new 7mm/beehive hardware was the Buell XB9, which came out in 2003. It had a factory 7500rpm rev limit and a two year warranty and valve train failures were almost unheard of, it was stable all the way into the limiter. This despite the new springs having roughly the same spring pressure as the old stuff. The "E" grind cams (.551 lift) in those motors had a lot to do with achieving this, with a lobe design that took advantage of the higher lift ceiling to ease the transitions between the ramps and the nose, making for a more stable valve train.

HD really showed the way on this, but they are not the only ones making cams like this for the new hardware. I'll stop there because I don't want to sound like an advertisement. My main message is that when you use cams that are made for the old hardware, with heads equipped with the new hardware, you're leaving a lot on the table.

But yes, using low lift cams does simplify installation with respect to cam box clearances. Clearancing a cam box is not difficult however and personally I would not let that deter you. It's just not that big of a deal.

If anyone has a cam recommendation for those heads I'm using I'm all ears.  I'm not intimidated by have to clearance the cam chest.  There's so many options