Cycle News - Archive Issues - 1980's

There's no contest when it comes to best rear brake - the KX shines. The YZ's Monocross suspension is second best to the eR's Pro Unk. The chrome-moly Sleel frame has a IOmm-longer steering head to increase strength and to reduce fork flex. Gusseting around the swingarm pivot area has been increased. The new gas tank, which holds 2.1 gallons, is reshaped and lowered on the left side and the new petcock is smaller. The front disc brake is 20mm smaller in diameter, and the disc material is changed from stainless to S45C steel. Pad material is also changed to match the new disc. The airhox and filter are larger in size to improve air flow and servicing. The airbox, side panels, rear fender and seat are interchangeable with the YZI25 and YZ490. Wheels are unchanged, but the front hub is much smaller to reduce weight, and M-22 and M-23 Bridgestone tires replace M-37 and M-38 Bridgestones. The motor in last year's YZ was so good that it probably could have gone unchanged another year without complaint. But Yamaha felt it needed modification to make the YZ's powerband even smoother than before. Port timing is different than, used , for the 1985 YZ, and the YPVS (Yama- ha Power Valve System) power valve is now 7.9mm smaller in diameter. The cylinder head now uses two 0rings instead of a single, flat head gasket; the head also has larger coolant passages, and a stronger headstay boss. The two piston ring locating pins are relocated to the upper edge of the groove (vs. the center), and, combined with reshaped rings, piston-tocylinder sealing is improved to lengthen piston ring life. To match to the new poning specs and smaller power valve, the exhaust pipe is redesigned, and the 38mm Mikuni carburetor has different jetting. . To hel p lower the cen ter of gravity, the left radiator is mounted 20mm lower, and the right radiator is mounted 10mm lower. A new cross tube provides more rigid mounting, aided by new radiator shrouds which now mount to the radiators and the gas tank. Transmission changes include more widely spaced fourth and fifth gear ratios; a 3.0mm-longer actuating arm on the clutch to lighten the clutch lever pull, and a slightly longer, folding aluminum shift lever. A new, longer-lasting aluminum silencer, redesigned handgrips and a stronger kickstaner lever provide the finishing touches to the new YZ. Riding There are really no big surprises this year when comparing the horse- 20 end and pull strongly through the gears in smooth fashion; on the track, neither of these bikes have a major advantage over the other in performance. But the Yamaha's motor is easier to maintain. The idea of having to tear down the eR's motor after every two hours of riding to remove carbon build-up off the power valves isn't appealing. Plus, when raced in longer events - such as GPs, which sometimes exceed more than two hours - the valves could stick open during a race. The Yamaha delivers the same kind of performance as the Honda without all that hassle. All four bikes have excellent transmissions, and missed shifts were fairly uncommon throughout our testing. The only complaint we had was with the Yamaha's shift lever, which is still a little short for size-nine-andlarger feet; the Yamaha's shift lever throw is also extremely short, whiCh takes a little gelling used to. Besides the previously mentioned hard pull experienced with the Suzuki, we were quite happy with the rest of the bikes' clutches. The Honda clutch is the smoothest of the four and has the lightest pull. Both the Kawasaki and Yamaha clutches are a little grabby, but other than that, work fine. The Honda's Showa forks, impressed us the most. They were the smoothest of the bunch, and we would do little to change them. The Yamaha's Kayaba forks are much improved over last year's mushy YZ forks. The stiffer fork springs, revalving and Alumite-coated damper rods really help out, but there is still room for improvement. The Kawasaki's front end is a,tad on the soft side, and stiffer (KX500) fork springs would probably help. In stock form, the forks feels too harsh and twitchy. The Suzuki's forks are set up badly right out of the crate and could use serious modifications. The fork springs are way too soft and there isn't enough compression or rebound damping; the fork is always working in the sti££est pan of its travel, making for an extremely harsh ride over smaller, squared-off bumps:'ln stock trim, the Suzuki's forks will pump up a rider's arms instantly on rough tracks. The most improved rear suspension of the four is on the Honda. Last year's Pro-Link didn't cut it, but this year's Honda has the best rear'suspension. Only the Yamaha's Monocross comes close to Honda's ProLink in performance. Both the Honda Honda CR250R Kawasaki KX250-D2 Engine type ..... Liquid-cooled, reed-valve, two-stroke single Bore x stroke 70.0x64.9mm Displacement 249cc Compression ratio ••• _.. 10.4:1 Carburetor Mikuni 40mm Horaepower ....•........ N/A Torque N/A Starting BYstem Primary kick Ignition .•••••............ COl Lubrication. • . . . . . . . . .. Premix Primary drive Straight-cut gears Final drive .•....... #520 chain Gear ratios Primary 55/20; 2.750:1 Final 48/14; 2.428:1 5th .....•... 24/24: 1.000:1 4th 25/22: 1.136: 1 3rd 25/18: 1.388:1 2nd _ 30/17: 1.764:1 1st 32/15: 2.133:1 Frame Single downtube, split double cradle Rake _..•............. 28° Trail 4.7 in. power of 1986 250s to 1985 250s. The most improved motor of the four is the Honda's. Last year's CR made good power o££ the bottom but flattened out too much on top. That's no longer the case with the new CR - it makes almost as much low end as before but the power doesn't let up like it used to, especially on top. The rest of the bikes aren't radically changed from the previous year. Actually, the Yamaha's motor has slightly less overall power. It does, however, still pull extremely hard off the bottom and continues LO pull and pull in a predictable and manageable way. Rarely is the clutch needed LO help the motor out when exiting tight turns. The Kawasaki has explosive power. It's super responsive to slight throttle movement at low RPMs, but lacks torque and mid-range pulling power compared to the Honda and Yamaha. It hits hard down low. mellows out in the middle, then hits hard again on top. It's a quick revver, and the transition from an exploding-type low end. to flat mid range makes the KX a little tricky to handle on rough, dry and slick tracks. The rear wheel likes to spin and suddenly shoots out to one side or the other when the throttle is quickly opened at low rpm. Given good traction, the KX is extremely potent, especially when blasting out of turns, but the front end likes to rise erratically when the rear wheel hooks up. Unfortunately, the Suzuki feels very much like last year's RM. It still has absolutely no power off the bottom, but now comes on stronger in the middle'and maintains decent power at high rpm. Coming out of tight turns, the Suzuki bogs off the bottom and takes too long LO come on the pipe. Fanning the clutch usually helps the Suzuki hook up, but the lever is very hard to pull in; it's nearly impossible to pull with one finger. The Suzuki's powerband is more suited to dry, slick conditions, where wheelspin can be used to advantage, gaining rpm and bringing the bike back onto the pipe quicker. Once the Suzuki reaches rnid-range and hooks up, it pulls hard and predictably. A Beginner or Novice rider will like the Suzuki's non-explmive powerband, but an Intermediate or Pro will want more low end, and more revs on LOp,too. Compared to each other, the Yamaha and Honda engines are the most evenly matched, plainly better than the RM motor, and marginally better than the KX's. Both have good low Front suspension type .... Telescopic fork Fork tube diameter 43mm Front wheel travel 11.8 in. Rear suspension type Single shock swingarm , Rear wheel travel _12.6 in. front brakes 8.7-in. disc Rear brakas 7.5-in. disc Front wheel 1.60x21 in. Rear wheel. 2.15x18 in. Fronttire 80/100-21 51M Dunlop K990 Rear tire .... 110/100-18 84M Dunlop K990 Claimed dry weight ..... 212.7 Ibs. Certified wet weight .. 235 Ibs. Overall length 86.2 in. Overall width 32.1 in. Overall height 48.2 in. Wheelbaae _ 58.3 in. Fuel capacity 2.1 gal. Ground clearance 14.8 in. Seat height 37.8 in. Colors •............ Lime green Retail price $2649 Engine type Water-cooled, reed-valve, two-stroke single Bore x stroke •••••.. 66.4x72mm Displacement ..•.....•. 249.3cc Compt'enion ratio ... '.' ••.. 9.9:1 Carburetor .•••...• 38mm Keihin Horaepo_r N/A Torque ..........•....••• N/A Starting aystem ....• Primary kick Ignition ....•...••.•....•• _COl Lubri,C8tion . _ _ _.• Premix Primary drive Straight-cut gears Final drive. __ #520 chain Gear ratios Primary , _ 63/21; 3.000:1 Final 53/14; 3.786:1 5th 20/23; 0.870:1 4th 21/21; 1.000:1 3rd 23/20; 1.150: 1 2nd 25/18; 1.389:1 1st 27/15: 1.800:1 Frame Single downtube, split double cradle Rake _ 28° Trail ...........•........ 4.4 in. Front suspension type •.•.• Telescopic fork Fork tube diameter 43mm Front wheel travel 12.0 in. Rear suspension type Single ~ shock swingarm Rear wheel travel ..•.... 12.8 in. Front brakes 9.4-in. disc Rear brakes ....••.. 5.1-in. drum Front tire ........•. 80/100-21 Bridgestone M-41 Reartire 110/100-18 Bridgestone M-42 Front wheel .. , ..••. 1.60x21 in. Rear wheel .......•. 2.15x18 in. Claimed dry weight 212.7Ibs. Certified wet weight 234 Ibs. Overall length 85.8 in. Overall width 32.5 in. Overall height ..••••..•. 47.8 in. Wheelbaae 58.3 in. Fuel capacity 1 .8 gal., Ground clearance .....•. 13.4 in. Seat height 37.8 in. Colors Red Retail price ' $2798

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