1974 Yamaha 125 Dirt Bike Test – is the Yamaha YZ125A better than the Yamaha MX125A, place your bet and lay your money down on the table….

There’s only one logical question and you know we’re going to ask it: “Is the 125 YZ worth the extra money?”

And of course, there are only two logical answers: “Yes and No.” Huh?

Back up for a minute and take a look at the differences in the two bikes. You pay about $110 more for a YZ than you do for an MX. The trick stuff they give you is easily worth that. No way could you buy it that cheap if you paid retail for it on the open market. Differences, basically, are as follows:

MX125A

• Paint – vellow and black
• Weight
• 16 horsepower
• Mild steel frame
• Oil injection
• Steel rims
• Normal ratio gearbox
• Ordinary gas tank
• Magneto ignition
• Little bits and pieces made out of ordinary metal

YZ125A

• Mostly silver gray
• Less weight
• 18.2 horsepower
• Alloy steel frame (lighter)
• Pre-mix
• Aluminum alloy rims
• Close ratio gearbox
• High-zoot gas tank that weighs exactly the same, but holds less
• CDI ignition
• Little bits and pieces made out of aluminum and magnesium

Let us add it up for you. Lessee . . . 35 bucks for the porting, maybe 50 for the frame difference, 30 for the rims, 60 bucks for the CDI and toss in 20 bucks for the odd bits and pieces. Disregard the visual stuff, as it does not make you
go any faster. Anyway, you get the idea. just about 200 dollars worth of goodies – some of which you may not need or want – but still, a bargain price for them.

What Yamaha has done, in essence, is eliminate the middleman. These things they have tacked on the YZ are pretty much after-market items that Yammie riders have been bolting on their bikes for years. If they could afford it, that is.

So in that respect, the YZ is most assuredly worth the tab. But we feel, in the final look, that overall performance is not that much different from the plain old MX version. Yes, the YZ is faster, but not that much faster. Lap times for most riders were about the same. And on a tight, twisty course, the standard model is actually a better machine, except in the hands of a top 125 class rider. Quite frankly, that top 125 class rider will not be on a Yamaha at all. There are better bikes in this class. Faster bikes. Bikes that handle in a superior manner. Bikes that cost more.

Which is one of the big reasons why so many riders are on the Yamaha line of budget racers in the first place. Most of those faster, better handling bikes cost well over a thousand bucks – and need additional money to make them “right.” Additionally, reliability on a stressed European 125 MXer is not all that wonderful. Just take a look at the activity in the pits between 125 Expert motos. Parts are constantly being worked on or replaced.

The Yamaha motocrossers, then, are primarily sold to huge numbers of Novices and play racers. They’re affordable machines, and do indeed seem to hold up well. None of the budget buyers are content to leave the bike alone – everyone is constantly diddling with the carb and hanging on one miracle expansion chamber after another – trying to make the damn thing run like a 400. Mostly, they just succeed in altering the power curve and shortening the life span. Such is life in the 125 class.

And life in the 125 class, in most of this country, is crawling with jillions of Yamahas. With this some-what sobering thought in mind, let’s take a very long, very hard look at the choice Yamaha is offering.

Obviously, the YZ has more beans than the MX. At least on top. But from 4000 rpm to 8500 rpm, the standard motocrosser offers almost a full horsepower more. Right at 8700 rpm, the YZ takes a deep breath and goes nutty. Take a close peek at the dyno chart and you’ll see how steep the power curve is. If riders of equal skill are placed on the two different machines, the winner will be largely dependent on what level of skill we are examining. If both riders are below average in riding skill, the rider on the standard model will probably turn quicker lap times, especially if the course is demanding.

The 125 MX is much easier to ride, with the powerband being tractable enough to allow trail riding. Second gear was strong enough for even the tightest turns on our test courses. As long as the bike had any forward motion at all, no clutch slipping was needed.

Some care had to be taken when riding the YZ – selection of the correct gear for the situation was an absolute must. Unlike the MX, the YZ didn’t like to be forced at low revs and would blubber and moan if the motor was asked to work. A moment too late at the shift lever often meant that the rider had to go down several gears to regain momentum. There simply isn’t room for error in the YZ’s engine.

In the hands of fairly skilled riders, the YZ would surely pull the standard model – at least down the straights. Horsepower is, after all, horsepower.

To get an idea of the difference in output, we drag raced both the bikes a whole bunch of times, switching riders back and forth for comparison. Invariably, the MX would pull the YZ out of the hole and stay a length or two ahead until the bikes reached fourth gear. Then, the YZ would start to stretch its legs and edge ahead of the MX. It’s fairlv safe to say that the YZ is worth about one to one-and-a-half lengths at the first turn. Top end on both bikes is about the same, but the YZ will get there sooner than the MXer.

One interesting sidelight took place while drag racing. A Honda 125 showed up on the starting line with George Ethridge aboard. We put Russ Darnell aboard the Yamaha YZ and let Him have a string of passes to get used to the bike. Then, George and Russ punched off 11 straight passes – the YZ winning all but one. Yup. In a straight line drag race, the YZ will edge ahead of a standard 125 CR Honda. A standard Honda, by the way, means one that is jetted too rich. As of this writing, Honda has not offered an assortment of jets for their bikes, and all of them come jetted far too rich. Shame. That means that, as delivered, a stock CR125 is down two, maybe three ponies. The Honda will, however, pull the MX version a bit. The big difference happens on the track, though, where the 125 Honda’s broad powerband (5000 to 8000 rpm) puts it on the YZ fairly well. Still, we preferred the power characteristics and output of the standard MX Yamaha over both the YZ and the Honda. It sure would be nice to own a Honda with a Yamaha MX engine.

HANDLING

All things considered, the MX handled better than the YZ. Yes, the YZ is lighter, but the narrow powerband made the bike spooky compared to the cheaper model. Horsepower directly affects handling, and these two Yamahas prove this point rather clearly. Both chassis are identical in dimensions, but the MX is much easier to ride quickly. And on bikes with marginal suspension components, this is forcefully brought to light.

Mounted on the rear of both racers are Yamaha’s verv own Thermal-Flow shocks. While these shocks work OK on the big Yamahas, on these lighter bikes they appear to be a classic case of overkill. Even some of our beefeater-type testers complained that the springs were too stiff. When you consider the fact that most 125 class riders are smaller in stature, one can only wonder why Yamaha didn’t cut that spring rate right in half.

Adding to the suspension problems is a set of forks (on both machines) that are positively loathsome in their performance. Yes, they move up and down – but that’s about all they do. Harsh impact is transmitted directly to the rider – causing hands and arms to tire prematurely from the beating.

And no, a change of oil will not cure the problem. At least not any oil in this world that we know of. These forks are not only a step backwards, but a giant leap into the past. They appear to be the very same trash that is mounted on the Enduro line. Maybe they’re not – but who really cares when they don’t get the job done.

Adding to the staggering miseries in the handling department are the tires. These wretched excuses for hobbies are sooooo bad, that we can only guess as to what the chassis really handles like. Yokamaha is the culprit and lack of traction is the crime. No Knobs to speak of are on the sides and any time the bike is leaned over, the square profile of the tyre creates a panic situation. Even when the bike isn’t moving. The shape and pattern are much like that of a 15-year-old Dunlop and you know how grim those things were.

Because of the square shape, if the bike has to make an abrupt change of direction on anything less than an ideal surface, the machine will take little breath-stopping hops outward. Or maybe a big hop. And on hard packed dusty surfaces. the rider will find himself in a constant state of recovering from a case of Terminal Wiggles. Like we said, the frame might be good, but we really don’t know because the rubber refuses to cooperate with the rider.

In straight line handling, the Yamahas both appear to handle better than in years past. Some rear-end hop is apparent, but not any queasy tank-slapping stuff. Aside from motocrossing the hell out of both bikes, we also took them out in the desert and entered a 50-mile hare scrambles. Here, both bikes worked well, but the MX version was clearly a better cross-country machine. Especially when climbing a loose hill, or attempting to shift up in deep sand. On the YZ, if the upshift was less than perfect, some clutch slipping or a downshift was in order. Too, the gearbox on the MX version proved more flexible under more conditions.

Under racing conditions, we were able to get only 30 miles out of the MX gas tank and about 25 from the smaller YZ tank. Definitely not even enough for a long moto. Of course, a trail rider or desert racer will want to fit a larger tank to thtbike. but any motocross bike should carry enough fuel for a 45-minute moto.

IN GENERAL

Braking has always been a Yamaha strong point- perhaps too strong on the rear, but both of these little racers are far too prone to rear wheel lock-up and subsequent engine stalling. Even after we bent the brake rod for sponginess (a cure we’ve used on many bigger Yammies), we were still stalling the engine often. Front brakes, on both bikes, are superb as per usual Yamaha practice. Water didn’t seem to have much effect on either end of the bike’s braking system. One or two seconds with the brakes applied got them back to original strength.

Shifting was beyond reproach on both racers- neutrals were caused by rider error, not by the gearbox. Even with the much shifted YZ, it was clickitty-click, with or without the clutch.

When first riding either bike, test riders complained of poor layout and feel. Nothing seemed to he set up for rider comfort. Knees are drawn up too high when sitting and the bars induce a strange crouch. The bike appears to have been designed for a four-foot, ten-inch rider with his crotch located an inch above the collarbone. Both bikes feel shorter than they actually are, but the tape shows 53 inches on the wheelbase, with another inch and a half left in the chain adjusters.

The more the bikes were ridden (like most bikes), the more comfortable they felt. Still, they are not relaxing machines to move around on. One always has the feeling of being on the end of a tall chair. Whatever.

BITS AND PIECES

Chains on the YZ and the MX are identical. Pathetic. They kinked and stretched, rekinked, restretched andretightened. We lubed and adjusted until we were sick of the damn things. Right before one moto, we oiled the chain up for a half hour and left it a little on the loose side. At the end of the mato, it was as tight as a drum. This was on the M!ier and we had similar happenings on the YZ. This chain should be taken off before the bike is ever ridden, and used to tie down a foo-foo dog somewhere. If you don’t mind the critter escaping, that is.

Servicing the air filter is a minor hassle. Seems the filter doesn’t want to squeeze out between the frame rails, so you have to deform it a bit. While you’re deforming it, crud from the dirty filter drops right down into the air hose and you’ll have to take that apart, too. The filter is one of those fuzzy foam things, that sheds hair like a sheep dog.

SUMMATION

Quite frankly, we like the yellow standard MXer much better than the YZ. It is a far more versatile motorcycle and much easier to ride. Because of the smoother power delivery, handling seems superior to the YZ and at racing speeds, the MX is less tiring.

We wish Yamaha had taken the extra $110 and spent it on suspension, though, instead of hot rodding the motor.

Face it, both of these bikes will be purchased mostly by Novices and play racers and they need better handling, not more horsepower.

To answer that question we posed earlier, yes, the YZ is worth the difference in money. But they could and should have spent the money differently. We’re positive that a rider on a properly suspended MX could beat hell out of a rider on a stock YZ. And that’s what racing is all about, isn’t it?

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