Optimize Your Timing

You Might Find a Little Free Power

1: Bob kicked things off by taking a few initial passes on the dyno. We were very impressed with the stock output of the Big Dog's 107 TP engine.

2: The dyno doesn't lie and show's our Dog putting out 99.8 hp and a whopping 116.2 lb-ft of torque in stock trim.

3: Bob removed the seat, disconnected the battery, and followed the ignition wiring from the stock module and unhooked it. The timing cover was removed and the stock sensor plate was removed.

4: We had Bob hold the stock sensor assembly next to the Dyna 2000i module that replaced it. The nose cone-mounted 2000i module is completely self-contained and replaces the module underneath the dash of the Big Dog.

5: While Bob was busy installing the module and running the wires up to the home of our new Dyna coil, Bill was removing the stock coil to make room for the new highoutput Dyna single-fire coil.

6: The Dyna coil wouldn't fit until Bill removed a little bit of the Big Dog's coil mount -- pointed out by his index finger. The coil is a very important part of the Dyna package and uses rare earth magnets to allow for a 40,000-volt-per-tower output in a small package. Rare earth magnets cost a little more, but are much stronger, more compact, and retain their magnetic pull much longer than cheaper metal-core or ceramic magnets.

7: At this point, we wanted to see how much power we could lose with a bad ignition setting, but not so bad that the bike felt like it wasn't running properly. Bob set the module for curve #1 with the VOES (Vacuum Operated Electric Switch) curve inactive, and set the initial static timing at 16 degrees before top dead center, or TDC. Our bike doesn't have a VOES, which is a vacuum-operated switch that slows timing under heavy throttle to retard timing and prevent pinging. The Dyna module will allow you to hook up the VOES wire to permanently slow the overall advance of the ignition curve, or it can be left unhooked for maximum advance. Curve #1 is very aggressive (about 35 degrees of added advance from our starting point of 16 degrees) and is intended for use with small displacement and basically stock engines. A large engine with high compression such as ours likes a slower and less aggressive curve to run happily.

8: Even though the bike felt good on the dyno, our test results clearly show that a lot of power was lost by improperly tuning the ignition system. Horsepower dropped from 99.8 to 84.2, and our torque dipped from 116.2 to 95.9 lb-ft. Bill proved that even though you may think your bike is running right during seat-of-the-pants testing, you can actually be down on power while thinking that everything is working properly.

9: Bill and Bob tried dozens of different static timing and curve choices. Here we catch Bob as he dials in what will be our best configuration of the day. Our high-compression engine was set up with 8 degrees of initial static timing with a full advance of about 24 degrees by running curve #4 on the Dyna box with the VOES circuit activated.

10: Here's a shot of the handy little sticker Dyna provides to attach to the back of your ignition nose cone cover. The sheet has all the switch positions needed to dial in the system for easy reference.

11: Bob takes one last set of passes on the dyno, while Bill Chambers tracks the results shown on the computer screen.

12: The guys at BCR squeezed an additional 7.9 hp and 6.1 lb-ft of torque. Our peak horsepower went up to 107.7, and torque topped out at 122.3 lb-ft. Although that may or may not knock your socks off, think of it as totally free and hidden power. We might have had similar gains with the stock Big Dog system if we had the tools necessary to adjust it. But since we didn't have a lot of time as our deadline approached, we went with the Dyna kit, and it really paid off in a big way.

Upgrading high-flow heads, carburetors, camshafts, or free-flowing exhaust systems are all items that can improve the output of your engine. It's not that difficult to add a little power if you have enough money to spend. The strange thing is, the easier the part is to install, the more expensive it is to buy. You'll save money in labor but pay for it with your initial purchase. Conversely, the cheaper the part is -- a cam for instance -- the harder it is to install. It requires special tools and more time, making your labor costs higher.

There are things you can do to improve the way your bike runs, without having to max out your credit cards and going further into debt. Some exhaust systems have removable baffles that can easily be taken out to provide more flow. You can even check your jetting with an exhaust gas analyzer and dial your carburetor in for a few free ponies.

We decided to optimize our Big Dog's 107 TP Engineering engine by fine-tuning our ignition system. While the stock ignition system on the Dog works great, it requires a special interface cable and software that we didn't have lying around to tune it. We also just happened to have a complete Dyna 2000i ignition system in our office that we were looking to put to good use. This Dyna module is very adjustable and offers four different curve variations that can be altered by hooking up or disconnecting the VOES (Vacuum Operated Electric Switch) wire. Also included in the system is an ultra high-output single-fire coil that easily fits in a standard-sized coil housing.

We contacted our good friend Terry Stewart at Dynatek to see who he'd recommend to help assist a tuning session on a dyno. Terry immediately suggested long-time Harley drag racer, Bill Chambers of Bill Chamber's Racing in Montclair, California.

Bill wanted to prove to us that we could most likely find an abun-dance of free power just waiting to be unleashed once the proper spark curve was discovered. And Terry Stewart from Dynatek dropped in to give us some information on the finer points of the system while Bill and Bob worked on the bike.