- Mar 31, 2014
- Reaction score
Forget everything you ever knew or heard about Pentons. Wad up and cast aside the notion that they must be good because they are expensive, or because they win a lot of enduros, or because the U.S. ISDT team rides them. Be prepared to change your mind if you rode one of the old ones and the pipey motor nearly flipped you over backwards and your leg muscles caught on fire because the ride and handling characteristics wouldn't let you sit down. Forget about the old suspension, which used to be good training for operating a jack-hammer. The new Pentons, which received radical changes early in 1975 and emerge as perfected models this year, are completely different from any Penton which came before. Based on the performance of this 175 Jackpiner and the Mint 400 tested last May, our sober judgement is that the Pentons have become the best enduro bikes available. First of all let's define "enduro." This term was once interchangeable with “dual-purpose” and applied to the entire body of dirt bikes that weren’t motocrossers. But more recently the dirt performance of Pentons and other true enduro bikes has so far surpassed that of street-legal dual-purpose bikes that the two are no longer comparable. Each has its own niche and each must have a separate descriptive term: "dual purpose" refers basically to the raft of street-legal trail bikes from Japan. Their performance on dirt and pavement is adequate, but not outstanding in either category. "Enduros" are entirely dirt-oriented and deliver excellent performance because they are specifically tailored for enduro competition and serious play-riding. Examples include Bultaco Fronteras, V75 Montesas, Pentons, Ossa Pioneers, MR Hondas, etc. Most are not street legal, but some are licensable at the discretion of state DMVs. In past years most Cycle staffers felt that Penton’s reputation as the ultimate enduro bike was not entirely justified. We found them to be pipey, stiffly suspended and skittery motorcycles which felt disconcertingly unconventional and were difficult and fatiguing to ride. They did well in the hands of experts who had mastered the special techniques necessary to make them work, but the average guy could do much better on a Yamaha. They won lots of enduros because the people capable of riding them were already some of America’s best enduro riders and timekeepers. The ISDT Team rode them because Penton paid the Team’s bills. A reputation built by expert riders tended to gloss over the bike’s shortcomings. Most magazine road testers were more often than not too caught up in the reputation to have an undistorted view of the machine.
Since last year all that has changed, because the bikes themselves have changed so much. They suddenly have acquired a critical asset called ride-ability. You feel comfortable and secure on today’s Penton, instead of finding the adversary relationship many people had with the old ones. They were very fast if you did everything right, but slip off the pipe or off the trail and the Penton seemed to take it personally. You couldn’t crank it on and use torque to recover because there wasn’t any torque and the bike didn’t steer for beans at slow speeds. Since it had to be ridden fast, from a stand-up position, only experts with vast, reflexive ability and tree-trunk legs could exploit the bike’s capabilities. Its disciplines were simply too much for play-bike people, who often bought a Penton hoping it would transform their riding but soon gave up after a few losing confrontations with its mean streak. Such is no longer the case. The new one is a magic carpet. The tiger-like performance has been retained, and a pussy cat personality added, so the 175 has become a bike the average rider can master. He will still have to adapt his style to the Penton’s high-rev power, but the transition from Yamaha or Ossa type engines is easier now because the Penton has a lot more low end and the new rear suspension improves tractability. Once you’ve mastered the 175 (a cinch to happen in 200 miles), it will never cease to amaze you. You'll climb hills that would stop most 250s. You’ll climb hills you j could never climb before riding anything. . The bike will dance through rocks with 10 inches of ground clearance and rush to a stop with marvellous brakes. The Jackpiner is always predictable. It doesn’t throw curves. You can always expect it to react the same way in similar situations. And it can handle any curves offered up by you or the terrain. Make a mistake and it will save you; if a rock lurks submerged in a mud-hole, you can hit it and live. The only way you’ll fall off is to do something really stupid. It’s yards better than any dual-purpose bike (size notwithstanding) and good enough to zero any enduro course capable of being zeroed. Bigger enduro bikes will squirt a little faster and pull the 175 in sand, but nothing handles better. Nothing. It’s likely that Penton didn’t consciously modify their bikes in the interest of improving ride-ability for the average person. To understand how the change occurred, you must understand what a Penton is and how it evolved. In 1967 a grizzled American enduro champion named John Penton made an arrangement with the KTM factory in Austria to build a line of lightweight off-road bikes he would help design. Since then his three sons (Tom, Jeff and Jack) and other Americans have ridden the KTM-built bikes in a half dozen ISDTs.
These same riders operate a re- search and development facility at Penton headquarters in Lorain, Ohio, and their ideas are constantly being incorporated in new models. While experimenting with long-travel suspension, Lorain test crews found that they fatigued less quickly because the smoother rear suspension enabled them to sit down more instead of standing on the pegs and taking the shocks with their legs. This discovery, coupled with six years of watching Czechoslovakia dominate lSDTs on sit-down Jawas, motivated both Penton and KTM to pursue a line of development which would add comfort without robbing performance. Their success in this pursuit has resulted in the amazing performance and ride-ability of today’s machine. An extra inch added to the middle of the frame and a re-contoured swing arm are changes made to accommodate the long-travel rear suspension. There is only slightly more wheelbase, and the steering geometry remains virtually unchanged at 29 degrees of rake and 5% inches of trail as measured in the Cycle shop. The frame is made of heavily gusseted chrome-molly tubing and painted grey. New reinforcing around the lower headstock prevents cracking should the steering head bearings loosen. To help make the Penton live up to its claim as an all-around competition machine, the frame is bracketed and the swing arm reinforcement ribbing drilled to accept shocks in seven different positions so a rider can adapt his rear suspension to any terrain. Positions range from 45-degree lay-down which comes stock and delivers 7 inches of travel to forward mounting 4-7 inches ahead of the rear axle. Last year's Ceriani gas shocks, which proved to be less than reliable, are replaced this year by gas/oil Marzocchis with 120- to 140-pound/inch progressive-rate springs. Besides delivering faultless action for enduro usage, the A Italian Marzocchis are completely rebuild- able with parts available from Hi Point, the accessory division of Penton. Damper-valve components are variable so you can experiment with damping rates. Spring pre-load is adjusted with a five-position cam. Since there is no air in contact with the fluid and the reservoir is generously finned, two of damping’s worst enemies - aeration and heat - do not debilitate the Marzocchi’s performance. A collapsible rubber bladder, filled with nitrogen at 28 psi, takes up most of the space in the finned reservoir outboard of the main shock body. As the shock body moves, oil being displaced by the piston and rod flows through a foot valve into the outboard reservoir, forcing the bladder to collapse proportionately. A valve on top of the reservoir controls nitrogen pressure and various plugs on the shock body facilitate oil draining. Press-fit silent-bloc rubber bushings in both eyes prevent bind and defy faulty installation. Light weight and excellent quality make these among the best of new-breed rear- suspension units.
A major benefit of controlling bumps so well is that the tire spends more time on the ground and traction is improved. Much of the wheel-spin common in older Pentons has been converted into hard acceleration. A stable, ground-hugging rear wheel likewise improves braking noticeably, an important consideration since a fully floating brake is mechanically not feasible with long-travel suspension. With a 200-pound rider our test bike worked best as delivered: shocks in the lay-down position, no spring pre-load and no change in compression damping - which is slight to begin with. Only a much heavier rider or terribly rough terrain would dictate stiffer settings. In front, the latest Ceriani fork easily matches rear suspension quality. Early eight-inch-travel Cerianis had binding and breakage problems at the slider/ stanchion joint. The new ones eliminate these problems with longer sliders and a reinforcing rib along most of their length. These Cerianis are referred to as the 200-millimetre versions because their travel is 200mm--an amount equivalent to 7.88 inches. Non-leak seals and air- bleed check valves in the upper stanchion caps help the excellent action stay that way. An extremely rigid triple—clamp holds the fork legs with a taper fit on the top crown so fork, bar and wheel stay solidly locked in alignment. You don’t have to brace the front wheel against a tree and tweak the bars back straight after unloading on the Penton because the fork usually doesn’t get twisted. There’s a lot of strength everywhere and the bike is relatively crash-proof because of it. It’s also heavy-251 pounds wet. But perhaps this weight contributes to one of , the 175s most important characteristics: terrain feedback to the rider. You can always feel exactly how the bike is reacting to your inputs. Nuances of traction, speed and handling come through to the rider without getting lost in the nervous, super-quick reactions common to ultra-lightweight bikes. Though 251 pounds is a bit bulky for a 175 competition bike, the Penton never feels heavy. It only looks heavy on paper. Its durability and feed-back effect far outweigh what is registered by the scale. Much of the Penton’s success in terms of control in feedback and handling comes from superb tires. The 3.00 x 21 Metzeler front knobby performs well everywhere, even in rocky desert terrain where fatter - section 3.50 tires are the rule. Penton’s own 4.00 x 18 Hi-Point tire works equally well in back and exhibits surprising wear. Previous Pentons’ wheel-spin ate tires voraciously, but this one should survive 750 miles. Wheels are also tough once the spokes bed-in (four or five tightenings) since Penton wisely chose the stronger ridged Akront rims instead of their muddles equivalents, which bend easier. Cross-three spoke lacing connects the rims to magnesium hubs containing incredibly good brakes. They get wet easily, are slow to dry and there is a slight wheel chatter on extremely bumpy downhills, but otherwise the brakes are faultless. Feel is again a strong point. You can tell exactly how hard they are working and how much more stopping power is left.
Neither brake will lock up without plenty of warning. New chassis components include a simplified chain guide, which provides better control of the three inches of chain sag recommended with shocks in the lay-down position; straight splines on the rear brake arm to replace the tapered splines, which used to strip; bigger sprocket bolts; a new brake-stay arm aluminium pet-cocks with more fuel-flow capacity replace the old steel ones; and an aluminium seat base eliminates the breakage common to fibreglass versions. Penton does not sell enduros, as such. You must first buy a motocrosser, then purchase an enduro kit for $95.00 and install it yourself - an aggravation almost inexcusable in the case of a machine costing $1525. Neither does the kit transform the motocrosser into a specialized enduro mount, with more low-end torque, wider gear ratios, etc. This hardly matters because Pentons are built as all-around competition machines and it happens that they are better cross-country bikes than motocrossers. The 175’s performance as an enduro bike is staggering. The engine contributes as much to this success as the chassis. Pentons have always produced awesome amounts of raw and somewhat less than useable horsepower. The 175 used to feel like a 90 until the pipe switched on and then it went berserk. This Jackpiner is different - partly because new cylinder porting raises low- and mid-range torque, but also because the suspension contributes so much to overall tractability. A larger intake and redirected transfers smooth the powerband without robbing the peak horsepower a 175 must have if it is to maintain speed averages in sand or up grades. This one made more power on the Webco dyno than any other 175 enduro Cycle has ever tested: 22.68 bhp at 8000 revs. That output explains why the Jackpiner feels like a 250 and why it can zero even tough enduro courses. At low revs (below 4500) the Penton won’t accelerate at all, but it hangs in there without dying until you shift. Steady acceleration above 4500 revs turns into a surge at 6500 and becomes a jet on after-burner at 8000. Nothing will stop it. An extremely low first gear ratio (31 turns of the engine to one revolution of the rear wheel) makes plonking on level ground possible, but on hills speeds must be sufficient to crank up at least 6500 revs. The Penton doesn’t like to be ridden slowly. You’ll have to slip the clutch to climb through rocks or go up tough hills without a running start. Four-stroke torque just isn’t there. But when did you see an enduro with 5-mph averages? Elaborate porting and lots of compression are mainly responsible for the engine’s high output. Huge finning and precision production help keep it reliable. A pressed-together crank with full-circle flywheels (-spins in ball-bearing mains supported by magnesium cases, which have been thickened for more strength this year.
The two-ring piston reciprocates in a shrunk-fit steel liner and is known for its strength. Air cleaned by a Twin-Air wet-foam filter and mixed with gas by a Bing carburettor ultimately makes its escape through a rather noisy high pipe that has no spark arrester. The silencing system should do a good job of capturing sparks, but tell that to a Forest Ranger. Spur gears transmit power through a rugged 10-plate clutch to a never-miss six-speed transmission that works with or without clutching. The whole engine seems able to survive even merciless punishment. Feeding high in the mountains where our 140 main jet was fat and low end power disappeared, we had to run the engine wide open and slip the clutch until it would hardly disengage to climb a series of rocky switch- backs. But after a mile of normal use, easy lever-pull returned, the friction point became definable again and no damage was discernible. At the District 37 "Tuff-E-Nuff" enduro in the Mojave desert the Penton ran nearly wide open all day in winning its class and would still start with one kick and idle evenly after the fray. Riding in that enduro served to strengthen our extremely favourable opinion of the 175. Sure, it needs a kill button; it needs new grips; the leaking kick-starter seal needs to be fixed and the seat cover needs stronger glue. And it would be nice if the shifter was hinged and if the carburettor needle was easier to change on the trail. But most of all it would be nice if the Jackpiner was a little cheaper so more people could experience off-road riding at its absolute best.