Daily Slideshow: Best Engine Mods for the Sportster: Part 1
Sportsters are small and perfectly formed, but as stock. The XL series was Harley Davidson's first Superbike, the V-Rod of its day, but if you want to get more out of it, here are some pointers as to what you can get and what to expect.
Introduction
Waking up a Sportster is easy initially, as you just have to overcome the neutered state the EPA requires them to leave the factory in. So pipes and an air cleaner will give you an effective boost. Once that thrill wears off, you can change the camshafts but after that it gets expensive as major engine modifications (often irreversible) will need to be done and reliability may suffer; although, it is your bike and your money, so read on and see where your budget and skill level can take you.
Part 1: Undoing the EPA Impositions
The main things that hold back the performance on a Sportster are the air cleaner and the exhausts. EPA is obsessed with noise and emissions, so restricted air cleaner designs, muffled exhausts and very lean fuel settings are in the way of unleashing the beast.
Changing the air cleaner, adding loud exhausts and adjusting the fuel mix is very easy on both carburetted and EFI (fuel injected) bikes, but different processes are used to change the fuel settings.
Choosing which parts to fit can be a daunting task and the price range of available parts even more of a challenge. To make sure you have parts that will fit and work those with less knowledge might want to stick to the Harley Davidson - produced "Screamin' Eagle" (SE) range; it fits, it works, as simple as that.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
Requirements
DIY Cost – $220-$1,750 (carburetor); $550-$2,500+ (EFI)
Professional Cost – $350-$2,500
Skill Level – Easy; only basic spanner skills are necessary, but you still need to take your time and know when to ask for help.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
Air Cleaner
Fitting an SE or K&N replacement air cleaner filter is as simple as unbolting the air cleaner cover, removing the screws that retain the air filter element and putting it all back together with the upgraded filter in place. These filters will allow the bike to ingest more air and it is the amount of air that gets burnt during the combustion stage of the running cycle that determines how much power the engine will produce.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
Exhaust
If you have limited mechanical skills, then stick to a slip-on muffler, so you will not run the risk of snapping one of the exhaust studs that mount the actual pipes into the cylinder head. A 2-1 system or a set of aftermarket 2-2 exhausts will likely give more power, but you need to have experience of removing exhaust flange studs successfully.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
Fuel Adjustments - Carburetor
If your Sportster has a carburetor, you will need to change the jets and the needle position. This is a bit of a science, but the basic rule for the setup described above is to add 15% to the main jet figure (eg 170 main jet + 15% = 195), and even if it isn't spot-on, it will stop the bike from melting pistons while you adjust the settings. The best guide to determining whether the settings are correct can be found in the Mikuni HSR42 installation and tuning guide, they make it really easy to understand and the guide is downloadable from their website.
The needle in the slide will require a 2mm shim fitted where the needle sits in the slide and the idle jet should be changed for a #45 or #48.
If you have an extra $450 or so in your budget, you could opt for a larger carburetor such as a 42mm Mikuni or an S&S Super E; both give noticeable gains in power.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
Fuel Adjustments EFI
To adjust the fuel setting on the EFI bikes, you will need a "Tuner." This is a small computer that interferes with the signals coming from the ECU module to allow more fuel to flow into the engine at any given rev or load range. They come in various types and prices and either have downloadable maps or manually adjustable settings. Some are "self-tuning" in as much as you just fit them and they work out what the bike needs with no input from you or your laptop. Look for Rev Tech, Ultima, Cobra, Vance and Hines Fuel Pak and Power Commander.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
883 - 1200
If your Sportster is an 883 and built before 2008, it can be bored out to 1200 using the existing cylinders and a set of 1200 conversion pistons. This will give you a 40% increase in power and cost around $450 DIY on top of the budget given previously or $1,000 fitted. For EFI bikes, you will need to add a tuner and have the ECU "Flashed" at a dealership (they need the whole bike for this) before fitting the tuner, this will add $650 to $1,000 to your budget.
For both types of bikes, a dyno setup will be the most accurate way of maximizing the gains to be had from the upgrade, but it could add up to $400 to the budget.
Post-2008 models will require cylinders and pistons, as they cannot be bored out using the stock cylinders. The conversion kit is $1,050 including gaskets and fitting around $500; you will also need the tuner and possibly the ECU flash.
Your Sportster will now be faster and louder! There is no downside to this level of upgrade, as it lets the bike do what Harley Davidson designed it to do way back in the day when exhausts were louder and life was less regulated.
>>Join the conversation about these engine mods for the Sportster right here in HDForums.
For help with your maintenance and repair projects, please visit our how-to section in the forum.
