Bultaco Pursang
BULTACO PURSANG
ON APPEARANCES, THE BULTACO PURSANG would seem to be a trend setter in some areas, while executing retrograde maneuvers in others. Design of the fiberglass components is, at first, startling and has one wondering whether the packaging people might have been given too much head. The design is such a complete departure from that of the new Pursang's predecessor that it might be suspected as a cover-up for a collection of last year's components. This, however, would be a totally false suspicion; the entire machine is just as new as it appears to be.
Beneath its mod plastic, the Pursang features an allnew frame of Bultaco's own design. Gone is the double down tube Rickman-designed item that Bultaco has been building under a licensing agreement for the past several years. This seems curious in light of the success of the early Pursang, and is further puzzling when considering the general trend to duplex frames in all manner of competition hardware. But no matter how the new design is regarded in theory, in practice it is an excellent piece. The large diameter front down tube arcs under and terminates midway beneath the engine. At this point, the rear section tubes tie in and then rise to meet the horizontal rear tubes Two horizontal tubes start at the steering head — one at the top and one in the middle — and converge just forward of the seat. From this junction, the two triangulating rear section tubes travel down to meet the main rear section tubes at the swing-arm pivot. Gusseting is liberally employed, particularly where the forward tubes tie into the steering head, and additional triangulation is provided by the peg bar which ties the two rear frame tubes together.
The absence of a center down tube to attach the rear of the engine to has been neatly overcome through the use of a fabricated bracket which intersects the swing-arm pivot at its center. The swing arm pivot is bronze bushed and sealed, and lubrication is applied through two grease fittings, one on each half-section. The new frame, like the old, has an unobstructed midsection — just the ticket for housing a large still-air box and air cleaner element. We hasten to add that this was not the sought-for product that gave rise to the design, but is just a fortuitous by-product.
One of Bultaco's principal reasons for developing the new frame seems to be to gain a longer wheelbase — three inches longer. The previous Pursangs were excellent handlers but had a nasty habit of "head shaking" at high speed on rough ground — a trait that is absent in the new model. Further, the new chassis is not prone to aviating its front wheel at those odd moments when two-wheel contact is the more desirable alternative.
The newness of the Pursang doesn't end with the glass and frame, but carries right on into the powerplant. Externally, the most obvious changes are the four — rather than three — mounting lugs, and the absence of the gear selector appendage at the rear of the engine. Also new to the Pursang, but not other Bultacos, is the off-center exhaust port. The intake, transfer and exhaust tracts are in keeping with Bultaco's earlier designs: they are generous, well contoured and represent an intelligent compromise between tractability and high performance, with the latter being slightly favored. For TT and flattrack riders, there is a margin that will permit some heads-up fiddling to gain still higher output on the top end.
Internally, the Pursang has been beefed with an additional ball bearing assembly on the drive side. This then provides three ball bearings on the crank, a roller at the big end and a caged needle bearing at the wrist pin. The alloy barrel is spigoted into the crankcase and thus increases the rigidity of the unit. A flanged steel liner is fitted to the barrel and the matching of ports and windows is quite good. The barrel and head are secured to the cases with four through-studs, and the head is further secured by two additional studs in the top of the barrel. An indexing pin in the barrel recess in the crankcase makes installation and alignment of the barrel a snap. Typical of Bultaco high-performance engines, the piston is fitted with two L-pattern rings and a trench head.
CYCLE WORLD ROAD TEST
The most significant changes to the powerplant are in the engine cases and gearbox. The cases are completely new, and while this change was obviously made to accommodate the five-speed gearbox, we are reasonably certain that the new unit was also designed to accommodate the 360cc engine that may be available later this year. With this in mind, we can only conclude that the 250 will prove to be super strong. Currently, however, the big item is the gearbox. Gear spacing is excellent with a stump-pulling low, a very slight step to second and then bang, bang, bang, through the top four. The spacing is so good that under hard acceleration the engine doesn't come off of the pipe, but just continues to pull steadily — and we might add, hairily!
The transmission, along with its extra gear, has gained a new drum shifter that affords a light, positive and short selector throw. These excellent gear changing characteristics team up with the close internal spacing to deceive the rider at first: engine pitch change is almost imperceptible, the gear selector feels as though it had hardly moved, and the only clue one has that everything is going well is that one must continually increase grip on the handlebars to stay aboard. The transmission has been further refined with wider gears than previous models, and a steel cap on the kick starter stop eliminates the chipping of the alloy stop that was experienced with earlier engines. Even the all-steel clutch has received some attention in the form of a beefy, double-ball-bearing center. A final point regarding the gearbox, and surely one worth mentioning, is that while it is new to the Pursang, it is not an unproven item, but was, instead, extensively developed in Bultaco's TSS road racers, as a six-speeder, and thus experiences none of the teething problems often found in new systems.
The intake side of the engine appears to be pretty straightforward, with a paper-element air filter, a still-air chamber and a 30mm Amal Monobloc. The carburetor, however, is a Spanish-made Amal that is tailored for twocycle duty. The differences existing between this item and the English version are slight, but the most important change is the smaller spray nozzle which permits the use of a smaller range of jets. In addition, the new carburetor employs the earlier, proven center main jet. Starting is a snap, and despite the high state of tune, the engine idles contentedly, takes throttle without hesitation, and runs cleanly on the top end. Some of the credit for the Pursang's good manners must also go to the exhaust system. It does an excellent job of getting rid of the "bad air," and its one-piece (header and chamber) construction precludes the messiness common to jointed systems. The pipe-tohead joint is handled neatly with a screw-in flange with an inner sleeve. The pipe is slipped over the sleeve and inside the flange and is held in place with two springs. The expansion chamber, with its integral heat shield, gets a bit warm and comes in contact with the rider's right leg when he is standing on the pegs. However, the situation is not completely objectionable, and because the new frame design doesn't permit internal routing of the chamber, we can readily accept the compromise.
Not surprisingly, the suspension on the Pursang is to be counted among the best. We say "not surprisingly," because we have yet to encounter a Bultaco that was not superbly suspended. The front units, mounted in alloy crowns, are Bultaco's own design, manufactured for them by Betor, and represent a near-optimum teledraulic fork design. They are light, have uncommonly long travel (over seven inches), and have excellent progressive damping, particularly on rebound—that point on which most units fail. The rear units are also Betor. The Betor label on a Bultaco is as generally accepted as "Cemoto" on the nameplate and the performance of these units is a known quantity. The fiveposition, variable-rate-spring units on our Pursang test bike left us with the feeling that "we've been here before —and liked it!" The units have about 3-1/2 inches of travel and their placement in the rear suspension offer more than four inches of rear wheel travel. Most importantly, the rear units damp — on both compression and rebound — as well as any spring-shock made, and for an encore, the units are the take-me-apart-and-rebuildme-for-a-couple-of-bucks variety.
While some are inclined to regard the "thumbs-up" hand as Bultaco's trademark, we are more inclined to bestow this honor on their infinitely variable "clip-on" bars. Happily for all, both items are retained on the Pursang. We have yet to find anyone who, armed with a 10mm wrench, could not be at peace with these units. The riding position on the Pursang is excellent. The pegs are high and set back almost to the point of being considered trialsworthy. Thus, they afford good stand-up control and further relate so well to the saddle that miles of hard riding are almost as pleasant as one might wish. The contour of the saddle is very good, but another layer of firm foam between the platform and the existing padding, would be a welcome thing for those long rides.
In the total view, the new Bultaco Pursang is an exciting piece of equipment. It handles brilliantly, is completely stable at high speed, is tractable despite its high state of tune, and is much stronger than the acceleration plot indicates; in standard form, the Pursang is geared too low for the U. S. market and will easily handle two additional teeth on the countershaft sprocket. The test bike was fitted with the alternate 17-tooth sprocket, and while this hardly provides optimum gearing for 1/4-mile acceleration, it affords a speed-time combination for that important 1/8mile distance that makes the machine outstanding in its class. Just how low the gearing is was dramatically illustrated to us when the machine repeatedly "lit off" the rear tire during acceleration runs!
All indications are that the Pursang will make its presence known in scrambles, TT and desert racing. Its appearance has already created a bit of a stir and we currently find the CYCLE WORLD staff evenly divided in their reactions to Pursang's aesthetic side, and on this matter, we particularly like the candidate Bultaco rally cry offered up by contributor Denis Murphy: "Viva el Pelicano Rojo!" ■
BULTACO
PURSANG 250cc
$885
SPEC1 FICATIONS
PERFORMANCE
