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Harley Davidson Dyna Glide: Performance Engine Modifications

The essential modifications that will make your Harley Davidson perform better than you could have imagined start out simple and inexpensive, and range up to the sky's the limit and god only knows. Let's look at some of the most common.

By James Bussey - April 29, 2016
Contributors: Bryan Wood

This article applies to the Harley Davidson Dyna Glide (1999-2014).

Just about everyone who owns and rides a Harley Davidson motorcycle wants to upgrade or personalize the motorcycle as soon as they get it. Every time I see a Harley Davidson I think of it as an extension or reflection of the owner's personality. There are countless ways to customize a Harley Davidson and just about every part can be customized in some form or fashion. No matter what you want to modify or customize, more than likely there is a manufacturer out there that makes a part that you have in mind. There are custom bars, pegs, grips, wheels and many other things. Chances are, if there is a part that you can unscrew, unbolt, or otherwise detach from your bike, there is a chrome replacement part out there. Engine improvements are no different. Two of the first modifications that most people make are exhaust and air cleaners, with dozens of options available. Another mod that goes hand-in-hand with these two is the EFI tuner. Next, if you want to get somewhat adventurous and eke out the maximum performance, you can upgrade the cams, or even bolt in a big bore crate motor. Very few people who have owned their bike for any period of time have done so with making one or more of these modifications, and once they start down the path, it is hard to stop.

A Dyna with a multitude of engine, brake and suspension mods
Figure 1. A Dyna with a multitude of engine, brake and suspension mods.

#1 Air Intake

Cobra Power Flow scoop type air intake

DIY Cost – $150-$500

Professional Cost – $200-$600

Skill Level – Easy; if you have basic mechanical aptitude and can follow directions, you can install most air cleaners.

The air cleaner is an upgrade that goes hand-in-hand with the exhaust, and you can do both together or one at a time. Most people upgrade both simultaneously. The Motor Company kind of has their hands tied when it comes to noise regulations, and the restrictive stock air cleaner is the result of this.There are hundreds of aftermarket air cleaner upgrades available for the owner and the good thing about the aftermarket air cleaner is that it can open the engine up, get some air flowing, and let it breath easier. Not to mention how it improves the overall look of your motorcycle. Upgrading the air cleaner on a Harley Davidson is one of the easiest upgrades a rider can do. On a scale of 1 to 5, with one being the easiest and 5 being the most complex, I would give installing an aftermarket air cleaner a 1. You can almost do it on your lunch break at work. A good looking air cleaner can totally change the dynamics and looks of your bike. This is a must do first step for anyone looking to upgrade their Harley Davidson Dyna for better performance and more power.

#2 Slip-on Mufflers

Screamin' Eagle Nightstick is tunable for more or less sound

DIY Cost – $250-$1,000

Professional Cost – $350-$1,200

Skill Level – Easy; this job requires removing just a few bolts, and sliding the new muffler on in place of the old.

The first mod that comes to mind, for me anyway, is upgrading the exhaust. A set of freer breathing, better sounding aftermarket slip-on mufflers is perhaps the cheapest and easiest mod you can make to your ride, and improves the look, sound and feel of the bike. There are more aftermarket mufflers for the Dyna than you could imagine, ranging from cheap, ugly, load straight pipes, to expensive mufflers nearly as quiet as stock, but better breathing. Putting on a slip-on muffler, or mufflers (depending on what configuration your bike has stock) is almost as easy as changing the air cleaner, and even more satisfying. maybe the most important thing to think about is whether slip-ons are enough, or whether you want to just take the plunge and get a full performance system.

#3 Stage 1 Download

Only the dealer can do the Stage 1 Download but it won't break the bank.

DIY Cost – $150

Professional Cost – $150

Skill Level – Easy; just drop it off at your local dealer.

Unless you have a fully outfitted computer vehicle programming shop, re-tuning your bike's fuel and ignition control computer is not possible. Luckily, your local dealer will happily re-flash your bike's ECM with what is commonly referred to as the "Stage 1 Download," usually for $150. This is a specially designed fueling map the Harley created for bikes with freer flowing intake and exhaust systems. If those are the only mods you are going to make, there is no need to spring for a more expensive EFI tuner upgrade.

#4 Full Exhaust System

Bassani Road Rage 2 into 1 full system

DIY Cost – $500-$1,500

Professional Cost – $700-$2,000

Skill Level – Moderate; this job requires mid-level expertise because of the amount parts to remove to get to the exhaust in some instances.

For maximum performance, you can't beat a 2-into-1 exhaust system; though, many people prefer the look of stacked duals, or a muffler on each side of the bike. A quick search of a popular web retailer returned almost 800 different products for the Dyna models alone. So I think it's safe to say that there is a a set of exhaust out there to fit your personality and what you are looking for. Some people upgrade their exhaust for performance, some change exhaust in an attempt to achieve a certain sound, and some even upgrade their exhaust for no other reason than looks. The sound of a Harley Davidson has deep roots in the riding community and people sometimes spend a good portion of their time and efforts chasing the perfect sound and rumble. Everyone reading this has seen the slogan "Loud Pipes Save Lives" and many Harley riders swear by it. To get a gauge of how popular swapping the exhaust is, the next time you are at bike night, look in the parking lot and see how many bikes out there actually have the factory exhaust. The number will be close to zero.

#5 EFI Tuner

Programmable Accel tuner for the Harley Davidson ECM

DIY Cost – $250-$1,000

Professional Cost – $350-$1,500

Skill Level – Moderate; most systems are easy to install, but require some time and talent to tune properly.

Now in the EFI age, if you upgrade the exhaust or air cleaner drastically, you must change the programming of the ECM to reflect these changes. Basically, the ECM comes stock from the manufacturer to rely on a certain fuel air mixture and upgrading the exhaust and/or air cleaner will change the ratio. Unfortunately, the stock ECM is not user adjustable; though, you can get it re-flashed at the dealer. Some owners decide to purchase aftermarket tuners (fuel management systems) that "piggyback" onto the ECM telling it what to do. There are also fully adjustable tuners that replace the factory ECM all together. These upgrades are extremely popular and highly effective in increasing performance and even sometimes fuel mileage. Typically, the more you spend on a tuner, the more you are going to be able to adjust it yourself. The simplest piggyback tuners have no user adjustments, but just richen the mixture beyond what the factory map would allow.

Pro Tip

Most tuners come with predetermined programs to tune your motorcycle. These programs are based on typical upgrades and are made for the masses. Therefore, sometimes they work on your motorcycle, sometimes they don't. If they don't, most companies have technical support that will create custom maps for you.

#6 Cams

A pair of cams for the Harley Twin Cam motor

DIY Cost – $200-$400 for cams, plus gaskets

Professional Cost – $400-$800

Skill Level – Expert; you have to take apart a good deal of the engine to install the cams.

If you have completed the others and feel like being a little more adventurous, maybe a cam is something you need to look into. A cam is the next thing that can be used to increase the performance of your motorcycle. A cam reprograms the mechanical aspects of the engine, changing when the valves open and close, how far they open, and how long they stay opened. Basically, there are two types of cam upgrades. There are ones that improve torque and power at take off, and the other is basically to improve top end speed. I would suggest you ride your motorcycle a while, get idea of what you want to do, and then consult the forums, or the cam manufacturer's tech line to discuss your options and long term goals of what you want out of your Harley Davidson motorcycle.

#7 Total Engine Upgrade

The complete 110ci upgrade kit for your current motor

DIY Cost – $2,000-6,000

Professional Cost – $2500-7,000

Skill Level – Moderate to Expert; swapping in a whole new motor isn't too hard, but adding a kit to an existing one is.

Just like with many cars, you can buy fully built crate motors to swap into your Harley Davidson for better performance. A Screamin' Eagle 120ci motor sells for $6,000, not including the installation, direct from your dealers parts and service counter, and it comes with a full one year factory warranty. You could also have your current motor rebuilt and improved at an independent shop, or even your Harley dealer, with bigger pistons, improved heads, cams, and more. You can even get kits directly from Harley to make your normal 103ci motor into the same specs as the CVO 110ci versions in the limited release models.

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