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Discussion Starter · #1 ·
I've been running my sporty out at the local strip. It's fun, but not fast enough. I'm looking for ways to pick up more juice. I was thinking about pulling my heads and taking up to the local machine shop to have about .030 taken of the deck. This should bump the compression a little. Anyone have any info about doing something like this?
 

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I used to deck a bunch of em, but it was always in combo with a good reworking.
 

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Discussion Starter · #4 ·
PONY said:
You will need to check valve to piston clearence when done. What cams and carb are you running?
Still all stock. Will eventually upgrade this too, but just don't have the loot right now. Figure decking the heads is my cheapest way to get some more performance. I am also going to clean up the intake and exhaust ports, and probably back cut the valves when I pull the heads.
 

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i wouldnt go for it til you can buy the rest of the setup so you can figure out what works best, or if u will have clearance troubles... ride the fucker, save up, and with a weekends work at some point come out haulin ASS!!!!!!!!!!!!!!!
 

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Is it an Ironhead or Evo? They make thin base and head gaskets for the late model Sportsters. I think one of the main things you need to look at on a late model is setting the quinch area at the minimum specs. You can usually do this with base gaskets, but you need to measure everything to make sure.
 

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Discussion Starter · #7 ·
51rat said:
i wouldnt go for it til you can buy the rest of the setup so you can figure out what works best, or if u will have clearance troubles... ride the fucker, save up, and with a weekends work at some point come out haulin ASS!!!!!!!!!!!!!!!
good point.
 

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What displacement you running?
 

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What have you done with the ignition? You have way more revs in there than the stock ignition will give you. If you are sending the heads off to get work done, get it all done now. You can grow into them. Piecing stuff out and upgrading a bit at a time is way more expensive in the long run.

Check these guys out - it will be streetable and leave you flapping like superman's cape.

http://www.johnsonenginetechnology.com/JETPAGES/packages/1200_sportster.html
 

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Discussion Starter · #11 ·
Ignition module is stock, but have a compufire single-fire coil.

When I get some money saved up, I'd like to do a carb, set of cams, ignition module, and bump the compression (either by decking, or with new pistons, or both).

thanks for the link, will check them out.
 

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40 mm CV is not exactly a racing carb, but it will work better than fine if you plan to keep riding on the street. Minor, inexpensive adjustments will go a long way.

Also, cams aren't too expensive. If it is going to stay on the street, watch the compression. Too much and you won't be able to run on pump gas. A cheap way to increase compression a bit is with base gaskets. Cheaper than head work, just carefully follow the directions to torque the bolts.

For the ignition, you really want more revs than anything else. Everything else is just changing the curve. For all out drag racing applications, this is important. For a daily rider and run what you brung at the track, keep it simple and reliable.
 

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Check in with your local dealer. HD has done a lot of work in all racing venues and has several performance packages from hot street to full race. Companies like S&S and Eldebrock also have upgrade packages for your Sportster. All of these packages are proven on the street and track and take All the guesswork out of upgrading your bike. Making one small change at a time, can be discouraging when you go back to the track and see little if no change and sometimes even slower times. You may have made the right change but the bike needs several more changes to take advantage of the first change. Race the bike as is now, have fun, save your money for a complete upgrade package and then step up. You'll be happier in the long run.. Good Luck and Always have Fun.
 

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Here's the rear wheel dyno sheet off of an 883 that I put a big bore kit on for a customer in the late 90's. The bike is still on the street and hasn't had any trouble since it was built. I used Wiseco pistons, Andrews N4 cams, reworked heads with bigger valves and some pocket porting, Python II exhaust and a reworked CV carb. It makes pretty good power for a daily ridden street bike with a CV carb.
You might look into Buell stuff too, they make a lot of reliable horsepower.
 

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Larry T said:
Here's the rear wheel dyno sheet off of an 883 that I put a big bore kit on for a customer in the late 90's. The bike is still on the street and hasn't had any trouble since it was built. I used Wiseco pistons, Andrews N4 cams, reworked heads with bigger valves and some pocket porting, Python II exhaust and a reworked CV carb. It makes pretty good power for a daily ridden street bike with a CV carb.
You might look into Buell stuff too, they make a lot of reliable horsepower.
Why the drop in torque / horsepower in the midrange? Were the baffles removed from the pipes for more top end?
 

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Python II are 2" drag pipes with AR cones built into them. I'm gonna assume the torque curve would have been flatter with 1 3/4" pipes and maybe some baffles. Probably wouldn't have hurt the HP either, but Doug wanted the 2" drag pipes. A different carb might have helped too. As the old saying goes--The customer is always right. He was happy with the scooter and just had the Harley house dyno it on a whim on one of his 100+ mile rides. We never dyno tuned it for max torque and hp.
 

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I had Python II's with 1 3/4 inch head pipes into a 2 inch muffler body - I think those are the Khromewerks AR 2" drag pipes. The Python IIs are a great two into two system - particualry for low to mid range and they sound good. Python III offer a deeper sound and a little more top end. But those 2" drags? Best way to tune those is to put a thumbscrew perpindicular to the pipe at the hole for the baffle bolt. Give you back some of the midrange, retains that great drag pipe sound, but loses a few HP on top. :(

Lots of upper mid and top end on that thing, though.
 

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hogtownhd said:
I've been running my sporty out at the local strip. It's fun, but not fast enough. I'm looking for ways to pick up more juice. I was thinking about pulling my heads and taking up to the local machine shop to have about .030 taken of the deck. This should bump the compression a little. Anyone have any info about doing something like this?
decking the heads on a stock bike actually will hurt your performance...oversize valves and heavier springs will increase your performance more so then decking the heads...don't do that unless you know what you are doing and if you are runnin a top fuel ride which you are not doing...take your heads off and send them out to Baisley Performance they will port your heads...coupled with a cam set pipes and pistons you can figure quite a bit of additional torque and horsepower...I did a set on my 98" Shovelhead let me tell you it is a hand full of fun...the reason why I say Baisley Performance is I trust them anybody that can hold top fuel records they know what they're doing...
 

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while you have the heads off..port and polish. Stage 2 ,maybe stage 3 if your feeling wacky
 
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