"Feedback"
"FEEDBACK"
DUAL PURPOSE YAMAHA
I recently read the Feedback column and the request for rider impressions of various kinds of dirt bikes so I thought I might respond by commenting on my present dual-purpose machine, a 1971 Yamaha RT-1 360cc Enduro.
This bike is designated as an enduro model, but perhaps is more at home on fire roads or cow trails. It presently has slightly over 11,000 miles on it, 6000 of which have been off-road use. As a road bike, the Yamaha has sufficient power, but incorrect gearing and excessive vibration. The cornering capabilities are necessarily limited by the trials universal tires. Speeds above 60 mph on the road are uncomfortable for any period of time due to the high engine speed and vibration.
The bike came equipped with turn signals and full lighting for road use. The turn signals malfunctioned and blew two bulbs after 200 miles and the headlight puts out only token illumina tion. The electrical system is just not adequate for such lighting devices, and as they are not necessary in the woods anyway, both were removed. .
Lxcessive plug touling plagued tile bike immediately after purchase, the cause of which proved to be improper carburetor jetting. The 32mm Mikuni main jet was changed from a 240 to a 210 and I switched from an NGK B9 to a Champion N-4. The result was less fouling, longer plug life, and smoother engine speed.
The drive chain and rear sprocket wore fairly rapidly and had to be replaced at 5000 miles partly due to negligent maintenance and also due to poor quality materials. The replacement rear sprocket, a 41-tooth compared to a 39-tooth original, and chain are both in good shape after another 6000 miles, and the two extra teeth provide more usable dirt gearing.
As far as the Yamaha's performance in the rough, a few major faults cause the bike to be less than admirable. The steering head and front forks had far too much flexing, which caused loss of control on rough cornering and at higher speeds. This was cured by adding an alloy fork brace, which prohibited any slack. Also, the rear shocks had poor damping characteristics, allowing the rear end of the bike to hop around. These were replaced with Koni units which added greatly to the control and stability. Another fault is the tendency for the engine to bog below 2500 rpm. It has good torque but throttle action is jerky and unresponsive at low revs. The 1972 models seem to have this problem solved with the reed valve.
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With a few other minor adjustments such as plastic fenders, serrated footpegs, and Firestone knobbies, the Yama ha has become a much better machine for the dirt while remaining in basically stock form. All engine parts are original and the power is still there. And on top of this, in over 11,000 miles not one drop of oil has shown its mark outside the engine or forks.
This bike has been a very reliable and fun machine that is capable of being ridden on the street or with a few basic changes you can turn into an adequate and legitimate enduro motorcycle.
Lee F. Hays Nashville, Tenn.
TRIALS IRON 1972 MONTESA COTA 247
This was my first trials bike, and was purchased in lieu of an Ossa MAR, which was unavailable for a long time last summer. The engine should be broken in by gentle trials riding, with plenty of cool-off time and clean oil. This was not done in my case, and caused a delay in achieving good trials performance, as when used as a slow road bike, the thing seems to run like a slow road bike. Out of the box, the engine was very jerky at low rpm, the skid plate was inadequate, there was no kill switch, and the air cleaner allowed gravel to pass through at will, presum ably being designed by an ornithologist to keei out small crows.
The jerkiness remained with the bike forever and ever, but was minimized by a switch to a No. 30 pilot jet from the 35 stocker. Side tabs were welded on the frame to protect the engine from rocks. When you have to pay for your cases you soon learn to cherish them. The filter was replaced by very thin free breathing foam, normal thickness spoil ing the low end power. The forks seals, made of soft swiss cheese, are designed as emergency rations, not to keep in oil. Ceriani seals fit nicely, and I fit some gaitors to keep them smiling. Now for the good part: I will stick my neck out and say that Cota trials suspension is the best in the world. Great small-bump sensitivity combined with a big margin for absorbing big bumps. I can't say enough good about the forks, in parti cular.
The long wheelbase of the Cota makes for good stability in sections, good for a beginner. With a 26m Mikuni fitted, the bike has started sec ond kick at down to -35 below, and never once required timing until about 1600 miles. Reliable to a fault; if it didn't run spot on, you changed the plug and rode on. It made a lot of tranny noise, but usually shifted. The gearbox is not a strong point, like the Ossa. The bike does its best on long rocky uphill streambeds, like Pipeline in the Scottish Six Days, but is hampered by the lack of Dunlop trials tires. If you don't believe me, try them and see. The bike seemed to improve with age, and I would go back to a `73 Cota anyday, all else being equal.
1973 COTTON-MINARELLI 170
I bought this in preference to all the other trialers I have tried, because of its light weight, agility, smooth en gine, and superb quality. All nut~ are elastic lock items, the welds are beautiful, and little conveniences abound, making working on it a pleas ure. The Minarelli engine is as quiet mechanically as any engine around, and also displays good quality control. The Dellorto carb is very good, with no flat spots, easy starting, and good low end. The air cleaner can be serviced without removing the tank, unlike most. The right side of the engine can be made 2 •nches narrower, by disposing of the ocker pedal shift and making a nar rower side case; this should be done at the factory. They must not have rocks around the Cotton factory, for the skid plate is absurd.
There is plenty of flywheel effect extant, and the engine's smoothness on an off camber mud section is a revela tion to me after the Cota. The front wheel is not used often in some sec tions, being light enough not to have to come down much. This is a good thing, too, for the suspension is bad news. When harshness is reduced with lighter oil, the forks top incessantly, and still are too stiff. I am spoiled, of course, after the Cota. Gearing is spot on as stock. The precise handling is as good as one could wish, with good ground clear ance that will leave Ossas hung up. riminally, no kill switch is fitted, though even when the idle is set properly low so that it will kill, acci dents will happen to the throttle, leav ing you with no device to shut off the engine save a hard to get to spark plug wire.
The four-speed gearbox allows only first for trials sections, crimping some rider's style and requiring a slow precise approach and riding style. It isn't a 326 Bul. Incidentally, there is no six-speed Cotton, as was falsely reported by an other magazine. The Cotton is consider ably less money than the 250 trialers, which are now over a thousand dollars, and is better in some ways, worse in others. Given the suspension it cries for, the bike would truly be superb. As it is, they should sell like hotcakes.
John Olsen Albert Lea, Minn.
'72 SUZUKI 550
I purchased my 1972 Suzuki 550 in June of 1972. It is my 11th motorcycle. To date I have 5765 miles on the machine. Most of the mileage has been put on 200 and 300 miles at a time. The last 1200 miles were put on during the "California 1000" road run, which my wife and I successfully completed in the company of another couple, on a 750 Suzuki.
Accessories added to the bike include a handlebar mounted fairing, sissybar, and a luggage rack-travel box combina tion.
Performance is more than adequate with good power between 3000 and 6500 rpm. It does have an obvious power surge at 5000 rpm. Seventy mph ruisin~ gets you 5000 rpm, which makes downshifting unnecessary when passing on the freeway. The only time the bike bogs or appears to work hard is when pulling a steep grade. Highest indicated one way speed so far is 105 mph sans accessories. The engine was not red lined at that speed.
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T.T. (Tavern to Tavern) racers might be disappointed in the handling and angle of lean available, but 99 percent of the riders should not find cause foi unhappiness. An 80 mph two-up dash down a winding road in Death Valley provided no unpleasant surprises.
Best gas mileage achieved was 52 mpg with 35 mpg being the worst. Oil mileage has been surprisingly good so far, getting 600 miles to a quart of Torco 30W.
The Suzuki is amazingly smooth and quiet at freeway speeds. At 60 mph it's almost as if someone switched off the engine. There is a slight but not bother some vibration in the foot pegs at 70 mph.
Modification to the engine have been limited to blocking off the crossover pipes to achieve better passing perform ance and relocating the condensers to underneath the gas tank. If the condens ers are left in the engine the heat tends to shorten condenser and point life.
The rather disappointing tour shoe front brake was discarded in favor of Suzuki's optional front disc brake kit which recently became available. The disc is a vast improvement and well worth the $115 retail price.
Only three problems have appeared so far: The seat is comfortable for only about 150 miles. After that you begin to wonder if the Japanese are trying to get even for World War II. The lacquer coating on the engine cases has begun to peel off. I plan to remove it entirely and buff the cases. At about 4000 miles the internal (welded in) baffles in two of the exhaust pipes broke loose, creating a terrible racket. Since the bike was over six months old U.S. Suzuki would not warranty them. Careful welding tempor arily repaired them. At 5000 miles the right muffler baffles fractured too badly to be repaired. I called U.S. Suzuki to see if they would consider replacing the muffler under warranty, because of the relatively low mileage, even though the portion of the warranty covering the muffler had expired. I was told politely by three different people (I don't give up easily) that they wouldn't even consider it, the warranty was up, and I would have to cough up $50 for a new pipe. Apparently U.S. Suzuki thinks it's perfectly all right for a $160 exhaust system to fall apart at 5000 miles.
My local dealer, Rancho Suzuki in Thousand Oaks, deserves a special men tion. The service provided by Norb, Lou and Mike has been outstanding even though the bike was purchased elsewhere. They'll get my recommendation anytime.
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Doug Kiassen Newbury Park, Calif.
'71 R/75 BMW
I have a 1971 R/75 BMW purchased in June of 1971. I have 25,800 miles on my BMW and have found it to be one of the most amazing motorcycles I have ever had the pleasure of owning. My suspension has never bottomed once even when overloaded 400+ lb. The bike leaks no oil whatsoever. The speedo and tach work ok, etc. Now for what I consider to be amazing. I got 14,000 miles out of the original plugs-24,000 miles out of the original points and 10,000-21,000 to my rear and front tires respectively-my brother has a new 500 Honda and my braking ability is not much lower than his.
Don't get me wrong I don't plug along. I have gone from the top to the bottom of California three times on my bike, I cruise at 75-80 mph, and on occasion have surprised a few 750 Hon das and the like with its quiet but quick acceleration and flawless high speed handling on twisty roads.
This is not my first bike. I put 20,000 unhappy, expensive miles on a 1970 750 Honda, most of them worry ing about my chain (twice through the cases), and I was forever adjusting the carbs and replacing plugs.
Yes the transmission clunks, but there are no false neutrals to fall into. The ignition switch is weird I'll grant, but I can't imagine any machine match ing my BMW for pure pleasureful, quiet, smooth, trouble free touring.
Tony Gatts Azusa, Calif.
