Sweet Tracker | Big Bore Hop-Up, Part Two

Tech In Depth

Here’s the rendering that The Harpoon did for me when the Sweet Tracker was just a twinkle in my eye. Now it’s getting that much closer to being done, thank god.

The following components were used because they’re awesome. SuperTrapp’s XR-750 style stainless steel high pipes, which feature the company’s disc tuning technology and mounting hardware; Daytona Twin Tec’s 1005S EX Internal Ignition kit, which includes the ignition, a new coil, and plug wire set.

Also pictured is Mikuni’s HSR42 Easy Carb kit, which includes the carburetor, backing plate, breather bolts, and all mounting hardware.

When the motor gets turned over for the first time, Amsoil’s new Break-In Oil is the perfect solution since it’s loaded with zinc. Zinc is really good for piston and ring seating in new/rebuilt performance engines.

1 Here’s where I left off last month: the top end assembly had been completed. This month I’ll finish installing the rest of the components to get it one step closer to tearing up the local dirt track.

2 The Mikuni HSR42 carburetor is a very easy installation process. Since the stock CV carb was already removed, Eric hooked up the stock choke with Mikuni’s starter nut (A), spring (B), and plunger (C) to work with the stock choke cable and knob. Once that was done…

3 Eric routed the throttle/idle cables to the Mikuni carb to ensure a proper fit.

4 Eric then mounted the Mikuni backplate adapter and O-ring to the stock air cleaner assembly backplate with the provided hardware. Note: Mikuni makes kits that include a new backplate with air filter and air cleaner cover, but I dig the stock “ham can” air cleaner, which is being used here.

5 Moving on to installing the Daytona Twin Tec ignition setup, Eric never reinstalled the stock ignition after installing the cams in last month’s installment because we’d be installing the new ignition here. The new ignition installs into the cam nose cone shown here.

6 Eric wrapped the ignition wiring with electrical tape in order to feed it through the bottom of the gear case to link up to the new ignition coil that will be installed later. You may be wondering why the ignition installs sideways, but that’s how the cookie crumbles for this particular model. Do not force the ignition module in place. Be very conscientious of the black plastic Hall effect sensors at the bottom of the unit when installing. If they get damaged, you’re screwed.

7 After routing the white/black, purple/white, green/gray, and pink wires from the new ignition unit to the factory ignition wiring Deutsch connector, Eric routed the remaining blue and brown wires to the supplied Daytona Twin Tec two-pin connector. After plugging the wires into the connectors, he routed them up to where the new ignition coil would be installed.

8 Eric removed the stock dual-fire ignition coil from under the backbone of the frame. He needed to install the stock key ignition switch to the new ignition coil.

9 The stock two-terminal ignition coil (left) is what’s known as a dual-fire ignition coil. Daytona Twin Tec’s three-terminal single-fire ignition coil (right) eliminates backfire and enhances idle quality. The single-fire ignition uses separate coil windings and electronics to fire each spark plug independently. Spark firing occurs only on the compression stroke. With a dual-fire coil, when the rear cylinder is fired on the compression stroke, the front cylinder is on the exhaust stroke. But when the front cylinder is fired on the compression stroke, the rear cylinder is already on the intake stroke. Under some conditions, a combustible mixture may exist in the rear cylinder at this point and the wasted spark causes a backfire through the carburetor. It was highly recommended that I use Daytona Twin Tec’s ignition setup to compensate for the performance engine mods and Mikuni carburetor.

10 Eric installed the single-fire coil and crimped on the provided ring terminals to the ignition wiring and hooked them up to the coil.

11 Next, Eric test-fit the plug wire length from the spark plugs to the coil and measured how much wire would be needed.

12 After figuring out the correct length, Eric snipped the plug wires for each cylinder and routed them up to the ignition coil and plugged them in. Installation for the Daytona Twin-Tec components was completed at this time.

13 Moving on to the SuperTrapp exhaust installation, Eric stuffed the exhaust gaskets into the exhaust ports of the re-worked heads…

14 …then installed the stock exhaust pipe flanges onto the new pipes with the stock circlips.

15 After mounting the front head pipe to the front cylinder first, then the rear head pipe, installation was nearing completion.

16 Eric slid the mufflers on with the provided clamps one at a time. Be sure to test-fit everything before tightening the hose clamps.

17 The SuperTrapp mufflers mount to the outside of the right shock with a provided bracket. I had to find some spacers to prevent the bracket from rubbing against the shock body. After finding the right spacers, the shock bolt was re-installed.

18 To cinch the mufflers up there’s a hole at the bottom of the same shock mounting bracket where Eric installed the provided hardware to finish up the exhaust pipe installation.

19 The last step with the SuperTrapp pipe installation was plugging in SuperTrapp’s tunable discs. The technology allows users to fine-tune exhaust note preference as well as play with torque output in the low, mid, and high ranges. The discs come with anti-seize and a provided Allen wrench for installation.

20 This specific kit included 24 discs (12 for each muffler), and Eric and I decided to install all 12 on each and decide whether or not to remove discs after some break-in miles.

21 Back to the air cleaner installation since Eric wanted to install the SuperTrapp pipes first to check for clearance issues. Once everything looked up to snuff, he installed the Mikuni backplate adapter and O-ring along with the air filter mounting hardware to the stock backplate with blue threadlocker.

22 The stock breather bolts were utilized for this application to get the backing plate installed to the cylinder heads…

23 …and the K&N; filter and stock “ham can” air cleaner cover were the last to be installed. That about does it for the installation of all the engine components for the Sweet Tracker. After everything was buttoned up, Eric started the bike and adjusted the Daytona Twin Tec ignition timing. He then played around with the adjustable idle mixture dial on the Mikuni carb until everything was running tip-top. Per Eric’s recommendations, I was instructed to put about 50 break-in miles on the bike, change the oil with Amsoil’s 20W-50 Synthetic Motor Oil, and also change the filter with the K&N; oil filter that I scotch-brited. Then after about 500-or-so miles on the bike it would be ready for some runs on the dyno. Check back next issue when we reveal what the bike pulled on the dyno.

In the neverending quest to be the fastest mofo on the block, and the quickest off the line, there are many routes for souping up your air-cooled V-twin. The stock 883cc displacement in my Sweet Tracker project was about as fast as a golf cart so I needed to juice it up with beefier jugs, and of course a set of higher flowing cylinder heads from Revolution Performance would be a good idea, too. RevPerf advised that Harley’s Screamin’ Eagle .536 higher lift cams would be the way to go with the RevPerf setup, so because I can sometimes follow directions, I went that route. Last month, I focused on the installation of RevPerf’s 1,250cc cylinders and re-worked heads, and Screamin’ Eagle cams. In case you missed the article, log on to hotbikeweb.com for the whole shebang.

For this installment, I wanted to show you some of the options available for getting the air/fuel…in/out, all with the proper timing of course via a new ignition system. For my 2000 XL883 Hugger Sportster, Daytona Twin-Tec’s 1005S EX Ignition kit ($414.26) would serve as the perfect accompaniment for the engine performance mods I made. The 50-state legal 1005S EX includes the ignition module, single-fire ignition coil, plug wire set, and installation instructions with detailed wiring schematic, and works with ’98-03 Sportster models, except 1200S models. Daytona Twin-Tec ignition kits are available for virtually every type of Harley-Davidson motorcycle, but the kit I ordered offers adjustable advance, rpm limit settings in 100-rpm increments, and switch-selectable single- or dual-fire modes.

Without certain components working in perfect harmony, you’re never going to get the optimum output that your motorcycle is capable of producing. I did some research on carburetors and tapped performance gurus in the industry for advice, and most said that a Mikuni carb was the way to go for this project. Mikuni’s HSR42 » Easy Carb Kit ($448.99) includes everything needed for installation. The carburetor alone includes a two-piece throttle slide with stainless roller bearings, lighter throttle return spring, low-speed air screw, and enlarged needle valve and float bowl. Other components included with the kit are a new backing plate, adapters, mounting hardware, and detailed installation instructions. The HSR42 kit is available in different variations, one which includes an Evo-style air filter and air cleaner cover, and the kit that I used, which is meant to work with the stock “ham can” air cleaner cover, but you’ll need a new air filter.

Enter K&N Engineering, which manufactures top-quality air filters, air cleaner kits, oil filters, and more, for any and all powersports industries. With more than 40 years experience in the business, K&N’s technology is tried and true. Since the Mikuni kit I ordered didn’t include a new air filter, I took the bull by the horns and grabbed the H-D-1388 Filter ($73.01) for my specific application. Having used plenty of K&N products in the past, I didn’t think twice about the purchase. K&N’s cotton-gauze, washable filters include a lifetime warranty, and flow more air through the carb than stock applications. And because I’d probably need to put some new oil and a new oil filter on the bike, I ordered up one of K&N’s KN-170C Wrench-Off oil filters ($15.99) as well. It features a 17mm nut on the end of the filter so installation/removal is a snap. It also features a synthetic filter media compatible with synthetic and traditional motor oils that increases flow rates and improves filtration. I ordered the chrome version, which I intend to scotch-brite to stick with the no-chrome-whatsoever theme of the bike.

With a new carburetor and ignition, I had to complete the trifecta with the right exhaust pipe. SuperTrapp’s Sportster 2-into-2 XR Style System ($795) was the only pipe I wanted because it pays a well-deserved homage to the coolest motorcycle » on the planet in my opinion, the XR-750. The high pipe style and brilliant stainless steel construction exquisiteness will not only add a visual appeal to the Sweet Tracker, but a nice boost in power as well. What else could a guy want? The XR Style 2-into-2 pipes also include SuperTrapp’s award-winning disc tuning technology, which affects how the exhaust system performs. How many discs you use depends on what you’ve got going on in the engine components department, and also how loud you want your pipes to be.

With the installation of all-new engine components, I didn’t want to fill the oil bag with any old type of lube. Amsoil recently introduced its Break-In Oil ($7.15 per quart), which is loaded with zinc and phosphorous additives to aid piston ring seating during initial start-up and break-in-mileage accumulation. Because it’s formulated with no-friction modifiers, Amsoil’s Break-in Oil flattens sharp peaks on newly honed » cylinder walls, resulting in a larger surface area for the ring face to seat against creating a dynamic seal that claims to increase horsepower, compression, and torque.

We asked motorcycle performance guru, Eric Bennett, from Bennett’s Performance in Signal Hill, California, if he’d give us a hand putting Humpty Dumpty back together again. Lucky for me, he obliged. Eric can handle any and all Harley performance needs, and he’s an all-around good guy. HB


Amsoil (800) 956-5695

Bennett’s Performance
(562) 498-1819

Daytona Twin Tec
(386) 304-0700

Contact your local dealer

K&N Engineering
(800) 858-3333

(818) 885-1242

Revolution Performance
(920) 892-2109

(216) 265-8400

[email protected]