If you're in the mood for more power from your Harley Davidson motorcycle, then few modifications can make the kind of impact that a different cam can make. The camshaft defines the characteristics, the personality, the soul of your motorcycle. If you get it right, then all is well in the world and you will be extremely pleased with this modification but if you get the cam wrong, then you can quickly grow to HATE the way your bike performs. You are wise to use caution, do some research, get real honest with what kind of riding and performance you want from your bike and then do some research and find the right camshaft for you.

If it sounds like selecting the right camshaft for your Harley can be confusing and even aggravating, then you're right because it can be. Years of experience have shown me that most prospective cam changers usually focus on the wrong things when picking a cam and end up choosing a cam that is poorly matched to their needs, and they end up very unhappy with the selection. Most prospective cam changers end up focusing on power output, specifically peak horsepower. A 120 hp cam surely must be better than a 100hp cam right? Wrong. The absolute primary focus of your cam search should center around the kind of riding you do and what kind of motorcycle you own. These two factors alone are probably the most important things you should consider, not how much peak horsepower CAM X made in that Dyno shootout in the magazine made.
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Matching Components

If you speak with any knowledgeable engine builder, they will tell you that the key to making power is in the combination. What they mean is that no single performance part can dictate the success of a build but rather all of the pieces that you choose need to be well matched to each other in order to produce the best results. If you install a race oriented cam into your portly bagger, then you are going to be disappointed. The following factors should play a large role in what kind of cam you select:

Riding Style: Do you ride two up a lot? Single? Loaded bike? Heavy bike? Light bike? All of these factors should come into play when selecting a cam.

Motorcycle Model: The weight of your motorcycle plays a key role in your cam selection. A high horsepower, high rpm cam will be a horrible choice for your near stock bagger but your Dyna with 11:1 compression, free flowing heads and solo seat would be a great candidate.

Compression Ratio: When the durations start getting long and the powerbands start moving UP then compression becomes critical to the success of your choice. Higher RPM cams will need more compression than other cams and it is critical that you match your selection to your engine.

Engine Components: Many cams are considerd to be a bolt-in, meaning you can change just the cam and retain the stock valvetrain if you choose. Other cams however, are not a bolt-in and it's critical that you understand the difference. Some CAMs will require different valve-springs, push-rods, cylinder heads etc and if you don't know the difference going in then you could be making a big mistake.

So all of this said, I am not trying to scare you off from changing your camshaft but rather just that you need to make sure you go into it with your eyes open.

Understand Your Limits

In order to maximize the results that you can expect from your camshaft then you must make sure that you have the right components in place already. If you are going to be changing the cams on any Harley Davidson then you want to make sure that you have a few components already upgraded. The minimum expectation is that you have already upgraded your exhaust and air cleaner to more free flowing units than the stock components. This isn't required of course, but you are leaving power on the table and will not recognize the best results without it. You will also need to either rejet the carburetor or modify the fuel curve with some kind of fuel management device if you are fuel injected.
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If you are not going to be reworking your cylinder heads and pistons then you need to limit your choice of cams to the "bolt-in" variety but don't fear, the choices are still nearly endless even when confined to a bolt-in camshaft. A bolt-in cam is a cam that does not require you to take the heads apart and replace the valve-springs and will typically feature a duration of less than 250 degrees and valve lift less than .500 inches of lift. These are relatively mild cams when compared to most of the dyno shootouts or magazine bikes but they will work with the rest of your bike and will produce outstanding power gains in the rpm range that you will typically be riding your motorcycle the most.

Understand Your Riding Style

I mentioned this already but let's expound on the topic a little bit. Time and again, the single biggest mistake that I see made in selecting a cam is getting to much cam for the bike. It is very easy to get enamored with the dyno charts that show 120hp but if you look at it closely, the peak powers for these types of cams are usually at the very top of the rpm ranges....how often do you take your Harley to 6500 rpm? Honestly. No I said honestly. The answer is never for most of us.

If you are riding a heavier bike or you ride two up often then you want a CAM that produces a good flat torque curve that comes on low in the rpm band and pulls like a freight train all the way up to 5k or so. If you ride a lighter bike like a Dyna or an FXST type bike then you can get away with something that moves the power band further up the RPM range. A great rule of thumb, (but not an exact science), is that a heavier type bike you should look for durations in the 220 - 235 degree range and then a lighter bike you can look at the 235 to 250 degree duration range. If you get up over 260 degrees then the power curve will be at the upper end of the scale and you should tread very cautiously here.

Torque Cams: 220 to 235 degrees duration with Overlap duration of 30 degrees or less. This type of cam is great for a heavier bike and will produce excellent torque and rideability in the low to mid-range.

Mid Range Cams: 235 to 250 degrees duration with lifts in the .500 and up range will produce good mid-range to top end power but they can often require valve spring changes and you need to be cautious here if you aren't prepared to do cylinder head work.

Top End Cams: Durations over 250 will move the power band to the top end and WILL require valvetrain work. You can damage your engine extensively if you don't know what you are doing with a cam in this ballpark. Consult a professional.

Understand What to Expect

It is important for you to understand what you should expect from a cam change. I have said it several times already and at the risk of repeating myself, don't expect to run the kind of peak horsepower numbers that you see in dyno shoot outs and in magazines. These types of CAMs require extensive engine work and are very purpose specific. They are not going to be best choice for a mild street driven motorcycle.

A solid bolt-in CAM in a TC Harley should be able to produce 85 to 100 hp and 100+ ft/lbs of torque. This may pale in comparison to the 120hp dyno King charts that you keep seeing but trust me, a Harley that puts out 100 ft/lb of torque from 2k rpm to 5k rpm is going to be an absolute BLAST to ride and will put a smile on your face all day long.

On the other end of the spectrum, an over-cammed Harley will be anemic from a stoplight and will never really get into it's power band most of the time. Riding double will be a chore and it will simply be a miserable experience all the way around. Do yourself a favor and follow our advice here and you should end up extremely happy with your Harley Davidson.

There is much more to proper cam selection than these basic guidelines but this advice will get you on the right path and give you some guidelines to use when researching the right cam. If anyone has any more advice to offer then feel free to comment below. Keep the shiny side up and we'll be publishing more advanced Cam selection articles in the near future.