Mini-Motocrosser Shootout
MINI-MOTOCROS SER SHOOTOUT
CYCLE WORLD TEST
Kawasaki KX80, Suzuki RM80, and Yamaha YZ 80: Fiercely Competitive and Nearly Equal.
Mini-motocrossers, both machines and their operators, are a specialized field. The bikes are race bikes, the riders are racers, and both bikes and riders are small and fierce. Last year we did a group test of
motorcycles for kids, a test addressed mostly to parents who’d be picking out the rug-rat’s first motor vehicle. We deliberately kept away from the motocross bikes, because they are powerful and fast and not suited for novices on the trail or the neighborhood vacant lot.
We’ve been catching flak ever since. You’ve read about how the youth of America is losing the ability to put pen to paper? Don’t believe it. You’ve been told kids don’t care today, that all they want to do is sit on their duffs and watch the tube? Wrong. No sooner did that kid’s bike test hit the newsstands than we were swamped with letters. They all began wdth the same request, a test of the real minibikes, the red-hot racers. From there they branched into the brand names and models, as in my Suzuki can beat any Yamaha in our club, and my Honda XR75 is the fastest bike in the neighborhood.
So all right. Enough.
We’ll do the group test, for minimotocrossers.
This test is more than that, though First, a note for parents, repeating our remarks from previous tests of kid motorcycles. The motocross models from three of the big four are competition machines. They have highly tuned engines. The suspensions are designed to work at speed, on a motocross track. The true pocket rockets are faster than many trail bikes with twice the displacement. They’ll carry the iront wheel through all the gears with a fully grown man aboard.
There are reasons for this. Minicycle racing is important. Most local tracks and clubs have classes for the 80s, with subclasses for beginner, novice, expert, etc. There are national championships. There are specialist shops dealing in speed equipment. Just like grownups, in short, (gasp!) and because there is a demand for full-race kid bikes, there is a supply. Kawasaki. Suzuki and Yamaha each build racers, for racing, along with the various 50cc to lOOcc play. kid. trail and camping bikes. Because the motocross crowd pays attention to details and technical advances and race results, the three factories each have done the complete job. The minicrossers are serious motorcycles, scaled dow n for serious kids.
Nor is that all. Some kids don’t race, either because the old man won't spring for it or won’t allow' it. or because there is no local track, or because riding is just as much fun as racing. And there are really tiny bikes, tot bikes as opposed to kid bikes, designed for the smallest of beginners and not just for racing. While we were rounding up and testing the minimonsters we included these other classes in the sessions, in the form of the Honda XR80. kid plavbike; Honda Z50R. kid bike with centrifugal clutch; Suzuki RM50. play/mx in toddler scale, and the Suzuki JR50. tiny tot bike with even an exhaust restriction so dad has final say in how fast is fast enough.
These four non-motocrossers are described later in this section.
For the main motocross group, we devised what we believe to be an accurate reflection of life in the world of minibikes.
The discerning reader will notice that the kids in the test are in scale. They really are kids, ages 12 to 16. rather than larger teens wringing out bikes too small for them.
Next, the kids have style. The riding group was recruited from staff families and neighborhoods. Most of them, especially the riders in the action and race photos, do in fact race at local tracks. They have full equipment, right down to motocross boots, pants and jerseys.
They’re good riders, as dazzling in person as they are in the photos. (Where were we when rich fathers were being handed out? Why were we born too soon?)
They have style and remember, these are not professionals or even national champions. You think these kids look good, reflect that at just about any local track in the U.S. you'll see riders just as fast.
Group tests and Christmas presents aside, when these kids grow up, when the best of this bunch hit the national circuit, about the time Bob Hannah becomes the Grand Old Man of Motocross, we are gonna have a talent pool the world will not believe.
The actual testing was done by these little demons, plus kids w ho ride for fun. in the woods and trails. Several are good, several are just beginning. We asked them all for comments on handling, control, power, brakes, all the findings we’d make ourselves or ask from any expert rider. The testing was done at a neighborhood track, beyond a farm whose owner’s kids are in the riding group. He and his neighbors built the track complete with jumps and berms and a water hole that comes from dragging endless garden hoses out to the pasture. No high buck fancy work here. This is a test of racing bikes that are raced by kids, on local and homemade tracks, so those are the conditions we created.
Now. the bikes:
KAWASAKI KX80
Kawasaki’s kiddie racer is a first year effort from Team Green. Like its competition, it looks like a scaled down 250. Forks are leading-axle, long travel and effective. Travel is 6.7 in. front and the canted shocks allow' 6.1 in. at the rear.
Wheel sizes are 14 rear and 17 front. The smooth rims lace to beautiful conical hubs front and rear. The lightweight hubs are partly responsible for the KX being the lightest 80 in our group, weighing in at 144 lb. with half a tank of premix.
The KX is powered by an 82cc reed controlled two-stroke Single that churns out a claimed 15 bhp at an incredible 11.000 rpm. Strangely, the transmission is only a five-speed but no one complained about it during the testing. Engine torque is good enough to pull the gear ratios without bogging and drag races with the other competitors proved them all equal.
SUZUKI RM80
Suzuki’s potent little RM80 has been popular with the mini-motocross crowd seemingly from its day of introduction. The desirable midget racer is better every year. The reed induction two-stroke engine has new intake and exhaust porting, 8.2:1 compression ratio, 28mm Mikuni carburetor, new pipe, and a six-speed transmission.
Suspension is also improved for '79. Leading-axle forks have 6.5 in. of travel and the cantilevered gas-charged shocks let the rear wheel move 5.8 in.
Front wheel size has grown from 16 in. to 17 while the rear remains a 14 in. Naturally both have full fledged knobby tires and mudless rims.
Styling was described by most of our mini-testers as neat. From its FIM-legal side number plates to its fenders, seat and tank, the 80 looks like a scaled down RM400.
YAMAHA YZ80
Yamaha’s offering for the 80 class is a mini-motocrosser that is much like big brother right down to the monoshock rear suspension. The rear shock has been redesigned and travel extended to 6.1 in. Forks are leading-axle jobs that give 6.5 in. of travel.
A double downtube frame ties all the parts together and has been strengthened this year. The swing arm is also mild steel and well triangulated.
A 3.60-14 rear tire drives the bike and a 2.50-16 leads the way. Both hubs are full width and lipless rims are employed.
The engine is a reed inducted two-stroke Single with a 7.0:1 compression ratio and CD1 ignition. A six-speed' transmission furnishes a gear for almost any situation and primary kick starting makes starting a stalled motor easy.
Styling is somewhat dated. The tank shape is old-fashioned and side number plates aren’t rear-set.
HOW THEY WORK
The evaluations and criticisms of the motocrossers were made at three levels. Principal reporters were the three experienced racers of the proper size and weight who did the riding when the bikes were being compared. Each of the three ow ns an 80-class racer, a fact that is less incidental than it appears.
Then the other kids in the neighborhood had their turns, for the novice reaction. And after that two older kids, 16 and up, thus larger (and more experienced) than the 80-class racers, did some hot laps in case they'd spot some subtle differences the younger set missed.
The Kawasaki made a good first impression on all the riders. “It’s a good slider,” said Roman, one of the class racers, “the controls are in the right places, the back is stiff but the front keeps the line and the rear doesn't kick sideways. The engine is mellow.” (Whatever that means. We forgot to ask our kids.)
Phil, another racer in the right age group, backed him up. “It’s a good jumper, turns well, has power. And it feels safer to me than the Yamaha does.”
Randy, the third racer, said “Suspension is soft, but it bites. Steering is okay, brakes are good, the engine lags when you open the throttle.”
Joe, the group’s non-racing but experienced trail rider, was dazzled. “It feels light, the front end is soft but I like it like that, and when you give it gas. it goes!”
The RM80 came through with equal praise.
Phil: “It’s nice. I think it's got the best handling. It takes the jumps smoothly, the front end doesn't skate and the engine feels fast.”
Roman: “The front end wanders in the sand some, but it's the best slider, especially when you put your foot down. Good power, good brakes and the rear tracks well.”
Randy: “Clean. I had some trouble shifting, it goes into second hard, but the rest of it feels perfect. Right there."
Next, the YZ80.
And a note of caution. We were shuffling the bikes around to make sure each kid got a fair chance, kids being kids, and the first rider on the YZ turned out to be Tommy, a 12-year-old who’s just learning how to ride.
He made one lap, got on the power too hard and low-sided as the rear end kicked out from under. No big deal, no injury except to pride, but a reminder, these little engines have more power than their exterior size would lead one to believe.
The racers had no trouble. Phil commented that “It goes as fast as the others, but the suspension feels stiff and 1 don’t think it handles as well. Narrow power band and you have to shift more often.”
Randy had no reservations. “This one is the best.”
“Why?” asked the adult in charge.
“Because he owns one.” chorused Roman and Phil.
“Stuff it. you guys,” said Randy. “It’s got primo power and the damping is right. It’s not too stiff for me."
More from Phil: “I think the YZ turns better because of the powerband, you can kick it around when the power comes on.
From Joe the trail rider: “The YZ works fine, but you have to keep the revs up. It feels light to me, and it’s fasti"
Then we began the actual comparisons, with the three racer kids racing. There was a series of drag races, in the form of starts.
There was no measurable advantage w ith any of the 80s. They all got off the line quickly, and because they weigh nearly the same and had just about equal power, they accelerate the same. Whichever kid made the best start was first into the first turn, no matter which machine he was on.
The same thing turned up in the corners. As the pictures show, the bikes corner at equal speeds. The riders used different lines for different circumstances, stuffing wheels on each other, bouncing off berms when available. But again, there was not enough to measure.
Lap times were a function of rider skill and experience.
At the end of the comparison speed sections, the kids had changed some of their opinions.
“I don’t like the KX,” said Roman. “When you land it feels like the forks flex and the back kicks out. It feels sluggish and I knocked it into neutral by accident.”
Both of the other 80-class riders agreed. Phil added that the Yamaha “doesn't jump out of corners like the Suzuki, so 1 like the Yamaha engine better. But the Suzuki has the better suspension.”
Roman: “The Yamaha was the easiest to ride. When you fan the clutch, the revs come up fast. But it’s under damped on rebound.”
Randy and Phil disagreed with that, although both said that the KX didn’t seem quite as fast as the other two bikes.
The two older racers then did some match racing. They liked the Kawasaki as well as the Yamaha and Suzuki, and we saw again that the race was a matter of riders instead of machines. One of the big kids races in the pro class and he beat the other kid no matter who rode which.
continued on page 52
continued from page 48
As a further test, the pro tried the Honda XR80 and lost to the other big kid on the KX. Nothing against the Honda is implied here. Fact is. the KX. RM and YZ are closely matched and the Honda isn’t supposed to be a mini-motocrosser.
But we have certain forms to follow. As usual for a comparison test, we took a vote.
Phil and Roman voted for the Suzuki.
They both own and race Suzukis.
Randy voted for the Yamaha.
He owns and races a Yamaha.
The two older kids, who at least are free from brand and model loyalty in this class, said all three were good, that they couldn’t find that much to choose between, but that the Suzuki had the best overall suspension while the Yamaha had the best engine and the best steering.
Joe thought all three racing bikes were as exciting as having a day off from school, and Tommy the beginner thought all three were more than he was ready to tackle.
We grownups didn't ride the anklebiters much, as we are plain too big to tell enough about them. What we did in group was act like fathers, that is, how will the racing bikes hold up under the sort of treatment kids hand out?
Not badly. The two day formal session was preceeded and followed by family riding and practice sessions. All the bikes in the group, racing or play or tot. had hours of hard use. Total damage was one dent, in the Yamaha’s tank, caused by a knee that landed on the tank w hen a kid fell. The engines, transmissions, shocks, etc., held up well. It’s safe to say that because these are competition machines, w ith engines that crank out lots of power at high revs, the three motocrossers will need frequent care and repair. But they didn’t come through as fragile as the 125 motocrossers tested earlier this year.
As a conclusion, we’ll have to score the thing a dead heat. Figure that the Kawasaki KX is a good start, impressive as a first effort from Kawasaki, even if it didn’t win over the Yamaha or Suzuki owners. The Suzuki is best known and there was agreement that it’s got the best suspension. The Yamaha looks to have the best power.
All of w hich means that the kid. or his parents, who wants to race w ill get a racing bike from any of the three. Might as well make the decision on the basis of price or dealer helpfulness, and might as well figure on making modifications if your local club has fierce competition. No one of these bikes is good enough stock to whip prepared versions of the other two.
Okay, kids. Do your homework first, see if mom needs help with the dishes and when you’ve got the chores out of the way. write those letters telling us w hy your bike should have been the winner.
SUZUKI
RM80
$679
YAMAHA
YZ80
$657
KAWASAKI
KX80
$699
