1250 kit

[rat097]

I have 97 1200 sporty and want to drop a 1250  kit in , has anyone done it before and is it worth doing for the extra 50 cc ? Can you notice the change once you go to 1250 from 1200. Have already got k&n intake jetted and exhaust done ( cycle shack slash cuts).Also intend on fitting stage 1 / 2 xb heads and pistons . Can anyone through some light on the subject ?
Cheers Rat.

[Panzer]

Rat,
You might want to give andyxlh or Wannbemayor a hollar on that topic.
Those guys are pretty good on that.

[mayor]

well the answer comes back to what your willing to spend to gain a little more.  The 1250 kit is nice because you gain a little over 3 cubic inches without boring cases.  You know that old saying "there's no replacement for displacement".     Depending on the supporting cast, 3 cubic inches could mean gains in torque of around 3-4ft-lb.   If you are already running flat tops (stock 1200), pistons aren't needed with the XB heads unless your planning on going pop-ups to increase compression or your planning on running the T-storm style beveled quench grooves.  I don't see cams mentioned on your list...what cams are you considering?

[rat097]

Yeah the cams , ive been looking at a lot of discussions and a lot of people have opted to go with S.E 551
                                                                                                                                    n8 andrews
                                                                                                                                    S.E .536
s.e were the more opted for this upgrade. Out of the discussions that I hear , the guys are talking h.p are they talking b.h.p or h.p at the crank , because if they are talking b.h.p , mate I'd be happy with 90 - 95 h.p for me . At the moment my 1200 is doing just on 60 hp rear wheel so the dyno says .My bike is running cycle shack slip ons , k&n filter insert with standard sporty cover , with cleaned up cv carb , cleaned up slide and s.e slide spring , jetted up to 45 and 200 main because i run the nology leads and plugs which spark higer due to its self capacitive leads. What do you think I would get the biggest changes out of to get to 90bhp. I was told the thunder storm heads with pistons and a hsr 42 mikkuni slide , with a s.e ignition module for my 1200 would get me up to the 85 hp mark , but I want to know for sure , from someone thats maybe already done it or someone that knows there stuff . Thats why im asking you guys .
Cheers Rick.

[mayor]

I'm at 83hp at the wheel with my T-Storms and N8's on a 1200.  My dyno and build details is in the dyno section:
http://harleytechtalk.net/htt/index.php?topic=669.0

The N8 are the only one of the three listed that will work as a bolt-in on the T-Storms.  The SE551 and SE536 cams are higher lift than the T-Storms can handle so if you want to run them a valve spring change is needed.  If you haven't bought the heads yet, the XB heads are said to flow slightly better and they have beehive springs which allow for either the lift of the SE cams.  I think a good combo for what you are looking for is XB heads, SE536 cams, hi-comp pistons and a Mik42 (but you might want to switch to the 27 tooth front sprocket because you'll be sqeezing everything pretty tight).  The XB heads are on the 2004 and up 1200 sportsters, so you may be able to find a set of take offs on Ebay. 

[rat097]

 Thanks for all that info , thats great , What ive also done is put a buell pulley on the rear which is a 55t and has knocked the revs down abit which is good for freeway use so if I get the ponies up ill be happy with that , about 300rpm less . But a bit hard to take off with two up but other than that its great.
Cheers Rick.

[mayor]

you want to be carefull with adding too much compression if that rear pulley is smaller than stock, a smaller sprocket in the front or a larger pulley in the back helps the engine unload quicker (although increases rpm's at highway cruise). The opposite (larger in the front or smaller in the back) will lower rpm's but make the bike more sluggish and can be prone to ping when the engine is loaded.   I have the 29 tooth pulley on the front of my sporty and I get a little ping starting out from a dead stop (not while moving though).  If your looking for a better running bike while hauling someone, you may be chasing the wrong target.  Generally gains you see from building HP on sporties are on the upper end of the scale.  You may want to rethink what you're trying to accomplish and pay attention to the torque curve.  I think this is where the 1250 is a benefit over a standard 1200.