This article is excerped from a Motocross Action Magazine from 1974 and is reprinted here for preservation of information. The article was timely and contains great information for a restoration buff or a VMX racer.
“Used to know this dude that lived out in the middle of a big swamp in south Georgia down amongst the cotton mouths, red ants and chiggers. He was what we used to call a good ol’ boy—made downright excellent home brew he called “Mother’s Milk” and had this big, mangy dog he just called “Yaller.” Which made sense, because he was.
Anyway, Yaller was a strange dog. Like, he had absolutely no socially redeeming qualities, but you still couldn’t help but like him a little bit. He was kinda fat, clumsy and snappier than hell, and not very good at all at the thing which he was supposed to do—which was hunting. Yet, there was something about Yaller, some indefinable quality which made you sort of like him even after he’d just taken a piece out of your leg to show you he really cared. Yaller had character, I suppose you’d call it; and if that was about all he had, it was still just enough to make you not mind too much having him around. You might avoid him, but you liked to know he was there.
It should tell you at least a few things about Yamaha’s MX 360 if we say that the bike reminds us an awful lot of Yaller. First of all, it is yellow; bright, searing, gawdawful, Suzuki-reminiscent, dayglowyellow. Second, it’s fat, heavy, an armful even for the Jolly Green Giant (who’d clash with the color scheme anyhow). Third, it’s clumsy. Fourth, turn your caution off for a moment and it’ll scrape your skin off quicker than Yaller’d bite the head off a chicken. And fifth, well, we kinda like it. Don’t ask why, it probably doesn’t make any sense.
Look at it. Like its stablemate, the MX 250, the 360 seems almost a step down from last year’s model. It’s a bit heavier, the same stuff is still wrong with it and (gasp!) it can be seized. Ever hear of a Yamaha that could be seized before? I mean really? Us neither. It all has to do with believing what you read in owner’s manuals.
THINGS THAT STOPPED MOVING IN THE NIGHT
When we first got the MX 360, we decided to take in a little nighttime motocross at Indian Dunes. Of course, we were gonna read the owner’s manual first to see what was what, but when the folks at Yamaha told us it was the same manual that they had used for the ’73s, we said, “Oh pshaw, why bother then?” So we hustled our cheeks out there with the other heavy iron artists, and in the second moto we seized it. Hard and fast.
Aside from this little (and unexplained) quirk, the 360′s engine is still the same strong, rugged, heavy powerplant of yore, putting out yards of usable, well-placed grunt. The bike doesn’t have a really exceptional low end, but there’s enough there, and there’s lots of mid-range. Whole bunches, in fact. You can rev the 360 till old Yaller (who also ran away a lot) comes home, but it’s not going to do you whole great gobs of good. The hot tip is to keep the bike running in the mid-range where the acceleration is strong and the power gets to the ground most efficiently. Try to scream it and the rear wheel will start to spinning and then start hopping sideways as the substandard old-model Dunlop Sports the 360 is shod with grasp halfheartedly for traction and the overweight rear end seeks out directions of its own. No fun at all, and not likely to win you many races.
In point of fact, the 360′s power plant is what makes the bike livable, even lovable. It’s rugged and dependable, with great bites of blubbering, low-throat power. As long as you keep the revs in the mid-range, that power is always there to get you out of the fixes that the marginal suspension and the over-weight mass tend to get you into. High-siding? Dial on more power. Front end chattering out in a fast sweeper? Stab a foot down and dial on more power. Things getting frantic in the whoopdies? Get the front end light and dial on more power. The MX 250, with no guts to spare in a crisis situation, was a hurtful machine. The 360, because it does have the extra grunt, does not necessarily have to be.
WHY PIERRE DOESN’T RIDE A STOCKER
The thing to remember about the MX 360 is that it weighs a hefty 251 pounds. Dry. Everything’s heavy. The frame is strong, but since it’s mild steel it also has to be heavy. Figure 40-plus pounds. The rear wheel comes in close to the 50-pound mark. The engine, for all its virtues, is one of the heaviest in the business. Fenders are plastic, but the tank is steel. The pipe has never been light, and with the new and very effective Skyways silencer hung on the end like an overweight German sausage, it weighs more. The pipe mounting brackets, the most ‘complex system since Skylab I, have gotta weigh a couple of pounds all by themselves.
So the MX 360 is way too heavy—and rear-heavy as well. All that ill-distributed weight is just too much for suspension components that aren’t exactly state-of-the-art as it is.
The official-type Yamaha Thermal Flow shocks at the rear are pretty good units, but in real heavy going they’re overmatched. Still, if you keep the front end light, stay in the mid-range and hang on real tight, you’ll generally make it through. At least on a motocross track. Desert types (perverts abound) will have to make some changes.
The front suspension is, at best, marginal, with poor damping and a tendency to bottom. Non-vented fork caps are part of the problem, dated fork technology the rest. Now that Yamaha seems to have gotten their front end act together on the GP machinery, it shouldn’t be too much to expect them to make improvements on their production models in the near future. As things stand now though, the forks will chatter enough on a bumpy sweeper to make precise tracking the stuff of dreams. And even breathing on that excellent front brake on a downhill is likely to introduce you to the intricacies of the endo as the forks bottom and the wheel toes in.
Breathe easy on the rear brake too, though for different reasons. It’s a full-floating, maximo-grabbing number, and if you lean on it any too hard things at the rear start hopping up and down real quick. Bending the brake rod will give you a little better feel, but it’s still touchy. Veteran Yamaha riders tend to be front brake riders, feeling that when it comes to the rear unit discretion is the safest course.
On a muddy course, however, the rear stopper may start taking matters into its own hands. The tolerances between the return spring and the pivot point on which it is wound are quite close, and sticky grit, once introduced, is very hard to dislodge. So after a muddy moto or two, the little bugger starts sticking. On. Whoops. If you ride the mud a lot, a spring added to the rear brake rod may save you some heavy-duty brake rub.
The combination of lots of weight, a skittery rear end and marginal suspension makes the 360 a tiring bike to race. The rider has to muscle the bike a lot, using maximum body English, and 251 pounds plus is a lot to try to throw around. Rider acrobatics are also slowed down by the through-the-frame pipe. It sticks out noticeably on the right side of the tank, and will eventually burn you through even the thickest set of leathers. If you ride the 360 the way you should, you’ll need extra padding at the right knee.
Because of the rear end weight bias and the substandard forks, there are few occasions during a moto when your weight should not be kept well forward on the 360. You have to really hang it up there in the turns to keep the front end tracking in any reasonably predictable fashion, and a steep uphill with good traction will have you looping faster than you can say, “Aieeeeee,” if you don’t keep things well forward.
The 360′s other accouterments are a mixed bag. Down in the cases you get Yamaha’s Omni-Phase Balancer, a little series of gears and other doo-dads which keeps things smoother but adds to the engine’s weight and complexity. You also get an automatic compression release—nice when it comes time to kick the beastie over, but don’t point it upwind in a sandstorm.
Rims are Akront-type and collect mud; tires are bad, the same old stuff. That goes for the handlebars, too, which are the same wrist-wrenching units that have graced Yammies from the first. Urg. Foot-pegs are nice, and the CDI does what it’s supposed to.
One further caution point on the 360 is the front brake cable. It’s routed through a little wire loop in front of the number plate, and it is very important that it stay that way. By routing it behind the number plate you run the risk of having it hang up in the triple clamp pinch bolts when you come off a jump, activating the front brake. You DO NOT want this to happen.
Like we said, ol’ Yaller is kind of snappish. But he’s still a halfway lovable old dog. Don’t ask why. Maybe it’s the way he’s always ready to go for a run, no matter how you’ve been treating him. Or maybe it’s the way he seems to try so hard, even when falling on his (and your) head. Or could be it’s just the way he sorta seems to snuffle up to you after snapping your Jofa off and saying, “Wanna try it again?” Whatever. We’ve got a warm spot for him in our garage—but we try never to turn our back on him”.
Yamaha 1974 MX360A Specifications
|83.1 in (2,110 mm)|
|374 in ( 950 mm)|
|44.6 in (1,130 mm)|
|Wheelbase||55.9 in. 11,420 mm)|
|Ground clearance||8.9 in. ( 225 mm)|
|Weight (dry):||234 Ibs. (106 kg)|
|Braking distance||50.5 h. (15.4 m) 31 m.p.h. (50 km/h)|
|Min. turning radius||82.7 in. (2,100 mm)|
|Type||Air cooled, 2-stroke, gasoline, Torque induction|
|21.42 cu.ln. (351 cc)|
|Bore and stroke||3.150 x 2.756 in. (80 x 70 mm)|
|Starting||Kick starter (primary kick)|
|Ignition||Capacitor Discharge Ignition|
|Spark plug||NGK B-8EV|
|Primary reduction||Gear, reduction ratio 64/24 = 2.666|
|Secondary reduction||Chain, reduction ratio 51/14 = 3.642|
|Gear box||Constant mesh 5 forward speeds|
|Low||36/16 = 2.250|
|Second||32/19 = 1.684|
|Third||29/23 = 1.260|
|Fourth||26/26 = 1.000|
|Fifth||23/29 = 0.793|
|Frame||High tension steel pipe, double-cradle|
|Suspension (Front)||Telescopic (coil spring oil damper)|
|Suspension (Rear)||Swing arm (coil spring oil damper)|
|Trail||5.1 in (129 mm)|
|Tire size||3.00 – 21 – 4PR|
|Tire size||4.00 – 18 – 4PR|
|Gasoline tank capacity||2.4 gals. 19.0 liters)|
|Oil tank capacity||0.6 qts. (0.5 liters)|