For Professionals Only
FOR PROFESSIONALS ONLY
A TT Triumph for Show and Go
Chuck Johnston
We set out to do a short article on the special street/TT Triumph which John Calicchio puts together in limited numbers and we no sooner finished the piece when John let us have a look at a newer-than-new competition-only machine that will be raced on the National TT circuit in 1978. Besides being the state-of-the-art in TT machinery, the machine impressed us with John's almost uncanny attention to detail and esthetics. As evidenced by the street TT bike detailed elsewhere in this issue, his bikes look as good as they run. The bikes drew crowds wherever we rode them. Questions like, "Is it a racing bike? I thought flattrack bikes didn't use brakes. What kind of paint is that? Do they still race Triumphs?"
The last question was heard more than once and we found ourselves recalling the successes of the British Twins in last year's TT season. No one wants to be pinned down on why an engine designed in 1938 can still be competitive but whatever the reasons, the 650cc engines rebored to 750cc are enjoying renewed interest and activity.
John started with a Trackmaster TT frame, identical to Trackmaster's half-mile model. According to John, different footpegs are supplied if you will use the frame for half-mile because the current trend is to put both the gear change lever and the brake pedal on the right side. We weighed a new Trackmaster frame and noted that at 31 lb. it was only 12 lb. lighter than the stock Triumph frame—we all expected a great difference. Another surprising comparison was head angles. The factory frame measured at 27 deg. and the Trackmaster at 26 deg. Again we expected a greater difference but John feels the factory frames were not far from right for dirt tracks. One other variation is that the Trackmaster frame carries the oil in the backbone of the frame, eliminating the need for an extra aluminum tank under the seat.
As on his street/TT bikes, John uses Slinger rims front and rear but instead of the 18 in. wheel on the street bike, the competition TT bike uses 19 in. wheels on both ends. The wheels are laced to Barnes competition hubs which attach to Hurst/ Airheart discs—double in the front and a single at the rear.
After looking at Pirellis and Dunlops for more years than we care to remember, we're seeing the new Goodyear DT-2 tires gain popularity on the dirttracks. John uses a 350-19 at the front and a 400-19 at the rear. As you can see in the photos, the profile on the rear tire offers a much wider contact area and according to John, much less wheel spin is evident.
The Ceriani flattrack fork is used up front but incorporates slightly different spring rates and damping than the model which John uses in his street specials. Mulholland-Interpart rear shocks are used and early tests indicate that running the units in the rear-most position on the swing arm offers the best combination of handling and wheel travel.
Flanders TT handlebars are used. Most of us were surprised at the narrow feel with only a 32 in. width but John tells us the rather crowded cornering conditions favor the narrow bars. Both the 2.2 gal. gas tank and the seat/rear fender combination are fiberglass. Between the narrow tank, seat, and handlebars, the feel of the bike is almost that of a trials machine.
The engine left the factory as a 1966 TR6 but has been bored to 76mm from the stock 71mm, which increases the displacement to 744cc. Hepolite pistons are used for a conservative compression ratio of 9.5:1. John explained that pistons with high domes tend to detract from overall power output because of a disruption of the flame front as it travels across the combustion chamber.
continued on page 167
$4800
continued from page 59
The connecting rods are built by John's own JRC Engineering and are forged aluminum. John bolts these to the heaviest flywheels he can find to further reduce wheelspin. Then the entire assembly is balanced and bolted into Triumph cases that have been modified for improved oil circulation.
The heads have been modified by conventional porting and polishing and the installation of 42.5mm valves. The exhaust valves are stock diameter and both valves have S&W springs. Kenny Harman's K&H # 15 cams are used for a total duration of 288 deg. on both the intake and exhaust. The cams are, according to John, identical to the Jomo #15 cams used with such success on the factory entries of the late Fifties and early Sixties.
The carburetion consists of two 34mm Dellorto pumper units that provide an impressive throttle response. As much as John hates to abandon his beloved Mikunis, he admits a power increase with the Italian carburetors. The spark is provided by a Gilmer belt-driven ARD magneto. Unlike the magneto used for years on the Triumph racing bikes, the new model provides a rotor and cap that allows the plugs to fire only at TDC compression rather than firing twice for each four strokes—once at TDC compression and once during the exhaust stroke.
It's difficult not to compare this bike with Jay Springsteen's XR750 we looked at a few months back. The bikes are both built to compete professionally on dirt tracks but the difference in appearance is incredible. While Jay's Harley appeared all business and almost brutal, John's Triumph looks more delicate and has a certain refinement. Of course John's bike will soon bear some of the scars seen on Jay's Harley. We can't help but feel it's a shame to push such a pleasing piece of machinery out on the track. Couldn't John just hang it on the wall in his office and keep it in its present condition? (£3
