| Harley-Davidson performance has been the subject | | | | fuel it can burn in each air/fuel charge. Ignite more |
| of many books. Many of these books go into great | | | | fuel, produce more power. Changing compression |
| detail, right down to the nuts and bolts. Our purpose | | | | ratios can be much more involved than bolting on a |
| here is to help you understand and define what | | | | few parts. |
| power you need and what is necessary to make | | | | USING WHAT YOU HAVE |
| that power. | | | | Harley-Davidson performance can be increased by |
| WHAT IS PERFORMANCE | | | | working with what you have. This is usually done by |
| Harley-Davidson performance means different things | | | | bolting on a set of slip-on mufflers and a high-flow air |
| to different riders. To some, it's just about getting a | | | | filter, along with remapping the fuel injection or |
| little extra power and better sound from their Harley. | | | | carburetor re-jetting. The cost will be about $1,000 in |
| Some want to make 100 hp or more for those stop | | | | parts and labor. The gain is usually around 10 |
| light to stop light runs. Or they might want to enter | | | | horsepower. |
| one of those dyno drags. That's all good, but when | | | | The next step is to replace the stock cams with |
| you modify your engine that much, you can create | | | | those that give higher lift and longer duration. By |
| problems with heat, noise, maintenance, reliability and | | | | installing cams with more lift (to open valves further) |
| rideability. Most Harley riders need power in the low | | | | and with more duration (to open valves longer), it's |
| to mid rpm range. | | | | possible to get a big performance increase from your |
| If your bike is going to make a lot more power, | | | | engine. This can be done without removing the heads. |
| you're probably going to ride it faster and harder. If | | | | Depending on the cams, it might be necessary to |
| you ride harder, you might want to think about | | | | replace the valve springs. These changes can take a |
| upgrading your brakes and suspension. | | | | stock Harley-Davidson from about 65hp to 85hp. |
| DEFINING POWER | | | | Going beyond this point would mean getting into the |
| When you talk about power, do you mean torque, | | | | engine. Now you're talking about replacing stock |
| horsepower or both? Torque is twisting power. It's | | | | cylinders, pistons, heads and other parts that go |
| this low-rmp twisting power that gets you moving. | | | | along with it. You would be adding quite a bit more |
| Horsepower is the higher-end spinning power that | | | | power, but you're also looking at some serious |
| keeps you moving. | | | | money. This serious money will get you to 100hp or |
| If you look at the difference between a | | | | more. |
| Harley-Davidson V-Rod and a regular Harley Twin | | | | IGNITION |
| Cam 96, you'll see that the V-Rod with its' 1200cc | | | | A stock Harley-Davidson ignition is designed to |
| engine puts out a lot more horsepower than the | | | | prevent engine damage and work with the |
| Twin Cam 1584cc, but puts out less torgue. | | | | restrictions set by the government. Preventing engine |
| The V-Rod puts out this horsepower buy spinning | | | | damage obviouisly protects your investment while |
| faster. The V-Rod is able to spin faster because of | | | | limiting warranty claims. |
| its' four valves per cylinder and dual overhead cams. | | | | The ignition module does this by limiting engine rpms |
| Basically it's because of the V-Rod's overall breathing | | | | by sensing detonation. An aftermarket module can be |
| ability. | | | | set to retard the spark and provide more push at |
| The traditional Harley-Davidson Twin Cam and | | | | lower rpms. Some ignition modules are adjustable and |
| V-Rods have much different engine characteristics | | | | have a variety of advance curves. These units are |
| which result in different power characteristics. Most | | | | priced from $200 to $500. When you really hop up an |
| Harley riders will stick with their Big V-Twins even | | | | engine, an ignition module can help unleash more |
| though the V-Rod makes more horsepower. I've | | | | power. |
| ridden V-Rods and didn't like the way they handled. | | | | USABLE POWER |
| HARLEY-DAVIDSON PEFORMANCE BASICS | | | | Let's look at where you want to make power. |
| An internal combustion engine is basically an air pump. | | | | Remember torque is the twisting/pushing power that |
| The faster you spin it, the more air it processes | | | | occurs at the lower rpm range and horsepower |
| within a given time. The amount of power it | | | | occurs at higher rpm ranges. For most |
| produces is governed by the amount of fuel it burns, | | | | Harley-Davidson riders, it make very little sense to |
| which depends on the amount of air it can breathe. | | | | try to increase engine performance to the 4,000 to |
| More air can mean more power. Turnning the engine | | | | 6,000 rpm range, when most of your riding occurs |
| over faster will also increase air and fuel flow and | | | | between 2,000 to 4,000 rpms, especially when doing |
| cause it to make more power. | | | | so negatively effects torgue. You can get good low |
| Compression is also a factor. The more air an engine | | | | to mid-range Harley-Davidson performance without a |
| compresses into the combustion chamber, the more | | | | lot of modifications. |