Vange & Hines Degree Wheel And Tdc Stops

VANGE & HINES DEGREE WHEEL AND TDC STOPS

CW EVALUATION

Because close is seldom close enough

TIMING. IT’S OFTEN the critical difference between excellence and mediocrity, between success and failure.

Without good timing, ideas wither, projects fail, organizations crumble.

And motorcycle engines run poorly.

For most riders, engine timing poses no special concerns; they either delegate such matters to the mechanics down at the local bike shop or use their engine’s stock timing marks.

But riders who perform engine hopups aren’t likely to get the most from their efforts if they simply rely on the stock marks, which not only are often inaccurate, but usually ill-suited for the requirements of modified engines.

That’s why good tuners instead use degree wheels, such as this $13 aluminum wheel from Vance & Hines Racing (14010 Marquardt Ave., Santa Fe Springs, CA 90670; 310/921-7461). It has the 360 degrees of a circle marked in one-degree increments around its outer edge, and a hole in the center for mounting it on the end of a crankshaft. Simple, but invaluable.

A degree wheel lets you find the crank’s exact position relative to Top Dead Center (TDC) at any point in its rotation. What this allows you to do, among other things, is install camshafts so the valves open and close exactly where you-or the cam’s manufacturer-think best; scribe your own custom ignition-timing marks; or measure the exact point of port opening/closing on a two-stroke.

Before you can determine the crank’s position relative to TDC, however, you must first find TDC; and the preferred way of doing that is via the positive-stop method. It’s simple: With the degree wheel in place, you thread into the sparkplug hole a “stop” that prevents the piston from reaching TDC. You then rotate the crankshaft in one direction until the piston hits the stop, and note the reading on the degree wheel; turn the crank in the other direction until the piston again hits the stop, and note that reading. Absolute TDC is located at the precise halfway point between the two degreewheel readings.

Vance & Hines is one of the country’s few sources of positive stops. Called TDC Stops, they cost $14 apiece and are available in three sizes-one each for 10mm, 12mm and 14mm plug holes. Each stop is about 6 inches long and machined from aluminum, with a knurled knob on one end and the tapered, positivestop portion on the other, just below the threads. For easy identification, each size TDC Stop is anodized in a different color: black for 1 0mm, silver for 12mm and gold for 14mm.

We found that the Vance & Hines Stops worked perfectly in a wide variety of engines, both two-stroke and four; VHR claims they’ll do the job in virtually any engine. They allow easy, no-tools insertion through the deepest of sparkplug-hole wells, and seem to have a long enough “nose” at the stop end to handle any combination of plug-hole angle and cylinder-head-topiston-crown distance.

The Vance & Hines TDC Stops and Degree Wheel are sold individually, so you can decide if you want the entire $55 set, or just the $13 wheel and the particular $14 stop that fits your engine. If you’re intent on squeezing every last drop of power out of a hopup project, this could end up being the best $27 you ever spent.