Mono-Mania – THE OPEN CLASS ULTIMATE

’75 Yamaha YZ Monocross by the Staff of DIRT BIKE

Let’s skip the old format for a dirt test this time, and put the conclusion up here – first. That’s breaking a precedent, but the YZ Monocross breaks precedents too. OK, here’s the conclusion: This motorcycle is THE ultimate weapon right now!

Oh, it’s got stuff wrong with it. It’s not the traditional maintenance-free Yamaha of the past. But even if the motor fell out of the frame once every day, it is still the finest racing bike you can buy, right now.

And this is why: It’s got power.

YZs always had power. So does this one. It comes out of the hole and out of the corners like a greased, goosed grand prix race car. It is screaming from the moment you crack it open. It breaks the rear wheel loose in every gear. When you’re on it, your favorite track gets shortened by what feels like 20 percent. Everything comes up sooner than ever before. See that corner up there? It’s here. Right now.

Part of that performance is the suspension. The monoshock system keeps you hooked up and driving. In all kinds of places you wouldn’t think possible.

Off jumps – where everyone else is sailing a short space through the air – you’re gonna have the back wheel down and pushing. Watch your weight, though. You will go over backwards if you don’t.

Through the hoops – where everyone else is rolling the throttle on and off – you’ll be making time. More than you ever imagined. It’s that good.

It also stops.

You’ve got to admit, brakes are the best way to stop. The YZ is equipped with the standard Yam front brake, lightened up for this bike, and that brake has been the racing standard for quite a while now. The back one isn’t as good, but it’s better than most. Do not lock it up. There are zero flywheels in that engine and it won’t even warn you, it will just stop.

Braking effectiveness is derived from the monoshock too. You know those nasty ruts and lumps that develop at the bottom of a hill right before, and halfway

through, the next corner? Remember how getting on the brakes hard used to make the rear end dance and the front end twitch? No more. Pull in the clutch and stand on it. It will stop before the corner. Got to get used to that.

It handles.

Last year’s big YZ took some getting used to. It wanted to stand up all the time. That made steering a bit imprecise. Contributed some front-end watch-out to riding the bike. Not so with the Monocross. At least, not as much.

Again, it’s the suspension that makes the difference. When you whack on the power (you do; there’s no choice, no such thing as dialing it on; it’s there instantly), instead of lofting the front wheel, the YZ hunkers down on the rear wheel and grabs hold. Of course, all that travel at the back end makes for a lot of geometry changes at the front; you do keep busy.

You also slide the YZ-M if you want to, but keep in mind that sliding with a tall bike isn’t the same as it was with those low-saddled machines you’re used to.

The Yamaha steers and it goes ’round corners. Not with the precision of a Maico or a CZ (inevitable comparisons; sorry), but you can depend on it.

Back to the suspension for a moment.

Riding the Monocross is a sit-down proposition, for the most part. It’s soft enough to let you rest through more of the lap. And though it’s moving, it only moves up and down; there is no side-to-side hopping, no birth of a tank-slapper when you’re sprinting down the straights.

This is one Yamaha where even the front end works. Of course, our test bike was equipped with a Number 1 Products fork kit. A change for the sake of getting as much out of the bike as possible during the test.

There was still one large problem with the front end.

It flexes.

If you’re better than a novice, you’ll find it moving forward and aft when you’re hitting the heavy stuff in the corners.

We found out that the YZs the Yamaha team uses, like Tim Hart’s, have different tubes

strapped on them. Theirs have larger diameters and they taper down to fit into the same clamps and all. We’re sure that the flexing caused this change. Pierre and Tim probably found out immediately.

Now on to the first major snivel.

Like we said earlier, this Yamaha breaks the precedent of the past. It is not a maintenance-free unit. Ours came apart every time we rode it. Not from misuse, or lack of care, either. It was prepped thoroughly before every ride. The problem is the use of cheap hardware.

Every nut and bolt on that machine seems to be made from the cheapest possible, melted-down-tin-can kind of metal. The bolts back out, the nuts strip, the silencer cracks and falls off.

The spiffy-looking straps that hold on the YZ tanks seem to shrink from sunlight. As it is now, it’s barely long enough to hold the tank on.

Those fuzzy air cleaners – there’re two on the Monocross – came apart in no time. Partly because they’re lightweight units, partly because the interior of the air box is just stamped, unfinished, very sharp metal that eats the filters.

The back tire was junk. It went away rolling the bike out of the van. That’s why the bike breaks loose in all the gears. We were going to put on a Trelle, but never did. We suspect that good rubber might make it hard to keep the front end down, but then, that might be fun too.

And the petcock…. even turned off it works too well. If you want to park this bike overnight, you’d best drain the tank. Otherwise, it’ll do it for you.

All of the above are examples of cheap details that irritate. All seem even more irritating when you consider the price of the bike.

The price is the next major snivel. Yamaha has no retail price for the YZ, its parts, or the tools you’ll need for the monoshock unit. Out here, the bike will cost the dealer $1205. God only knows how much you’ll pay.

The monoshock unit cost the dealer $116.07. We have no idea when – or if – you’ll ever have to replace it. But you will have to work on it. The Yamaha team changes the oil and replaces the O-ring within the body every six or seven races; they make pressure checks all the time. Ours is considerably softer after five orsix weeks than when we first rode it, so it must be time for ours to get overhauled, or at least, to get another shot of nitrogen.

One last item of information about monoshock maintenance: We spoke to Gary Surdyke on the phone and he reported that his shop had been racing the YZs for about a month, but they hadn’t done any maintenance to the suspension at all yet. But they didn’t have the tools, either.

We’re guessing, but we figure that all the monoshock tools have got to cost about $100, dealer price.

There is an escape for the privateer, however – he really doesn’t have to use all YZ parts. Most MX and YZ items are bolt-ons, and using MX stuff should save some money. For example, a YZ brake pedal runs $27.02 (list price this time), but the MX version costs $6.54. A YZ fork slider costs the dealer $91.70, but the MX lists for $37.01. Use your discretion.

Back to an overall look at the YZ360B:

Despite the zero-flywheel and radical 125-like power that keeps you busier than Smokey the Bear stomping on matches in the middle of a freak forest, the 360 is an extremely competitive racer. It puts more on the ground, goes faster through the rough and is easier to ride longer than anything else in the class.

We have to reiterate: Right now, it is the ultimate weapon. We keep saying “right now” because we have no idea what’s coming next. This last year has been a blowmind for picking a bike. Just when you think you’ve found THE machine, someone unloads another dynamite scooter that’ll destroy your mind and suck you up its restrictive silencer.

BITS AND PIECES

All horribly cheap.

Except, believe it or not, for the front tire and the rear hub. Two more places where the YZ breaks Yamaha’s traditions. The front tire was nearly as good as the Trelleborg we slapped on just to see what we could see. And you know about Japanese rear hubs: Usually they have more parts than the engine. Pull the rear axle out and parts drop on the garage floor for 15 minutes. Not so with this bike. Not only that, but the thing is incredibly light. We could hardly believe it.

A SCATTERING OF SUMMARIES

“If there’s a berm, it’s boss.” – Bobby Messer

“Best handling bike I ever rode; goes around corners easier than a Maico; and I can go faster on this bike over the hoops than anything.” – Tom Brooks

“Very impressive.” – Randy Sutter

“It’s nice. Burnt my leg – just like everybody else, but it’s the best bike I’ve ridden today.” – John Speight

“Works pretty good in the back; put a Maico front end on it and it’ll be bitchen.” – Luke Messer

“That is nice. It just won’t hurt you. You can go a long time

without getting tired. It does burn both legs, but it corners any way you like it.” – Jim Connolly

“The front end washed out and it didn’t burn me; I had some trouble downshifting and had to clutch it, but it’s super. The rear end is unbelievable; that has got to be it, a real breakthrough in handling. It’s the best handling I ever felt.” – Nate Sciacqua

“It works. It’s dynamite.” – George Wegner

“I want one.” – Chet

YAMAHA 360 YZ

• PRICE: $1600 (approx.); whatever traffic will bear
• ENGINE TYPE: Two-stroke, air-cooled, single
• DISPLACEMENT: 351cc
• BORE Et STROKE: 80mm x 70mm
• COMPRESSION RATIO: 7.0:1
• CARBURETION: 34mm Mikuni
• HP @ RPM: (claimed) 39 (actual)
• CLUTCH: Wet
• PRIMARY DRIVE: Gear (3.083:1)
• GEAR RATIOS: 1) 1.789:1 2) 1.609:1 3) 1.166:1 4) 1.0:1 5) .857:1
• FINAL DRIVE: 15 -tooth countershaft 48 -tooth rear sprocket
• AIR FILTRATION: Twin wet foam
• ELECTRICAL SYSTEM: Hitachi CDI
• LUBRICATION: Pre-mix
• RECOMMENDED FUEL: Premium
• RECOMMENDED OIL: Yamalube
• FUEL CAPACITY: 6.8 liters (1.8 gallons) .
• FRAME: chrome moly, double-loop monoshock
• SUSPENSION: (front) Yamaha forks 200mm travel (7.7 inches) (rear) Monoshock 150mm travel (6 inches)
• WHEELS: DID rims, shoulderless aluminum
• TIRES: (front) 3.OOx21 Dunlop (rear) 4.50×18 Dunlop
• DIMENSIONS Wheelbase: 144.3 cm. (57 inches) Ground Clearance: 16.3 cm.(6.5 inches) Seat Height: 85cm. (33.5 inches) Handlebar width: 90 cm. (35.5 inches)
• Weight: (claimed) 98.5kg. (217 pounds) (actual) 105.3kg. (232 pounds) with no gas  (on front wheel) 45% (on rear wheel) 55%
• BRAKES: Conical drum
• SILENCER: Skyway
• SPARK ARRESTOR: No
• PRIMARY KICK: Yes

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