Long-Range Test Yamaha Yz465g
Long-Range Test Yamaha YZ465G
The Motocrosser We Couldn't Break
Sometimes we are so overwhelmed by a test bike we can't stand to give it back. The Yamaha YZ465G was that kind of bike. Our hardest dirt riding editor decided he simply couldn't get along without it. Yamaha agreed to a longrange test and the YZ started on its year of torture.
One year and more than 4500 mi. later, we’re sad at its departure. It was the strongest, most dependable open motocrosser we’ve tested. Mileage traveled was estimated because the bike was used most of the time without a speedo. The first 4500 mi. of its existence the bike was mostly used as an off-road play bike. But not play in the normal sense. Playing to the guy in charge of the 465 meant at least 100 mi. of desert every week or 300 to 400 mi. of Baja riding. Play speeds were mostly as fast as the bike could be ridden with the gearing raised two teeth at the countershaft and lowered two teeth at the rear sprocket. Occasionally the gearing was put back to stock for 100 mi. or so of mountain riding through the Pines.
The bike was enduroized for the Jack Pine National. Although the rider crashed out and didn’t finish, the bike didn’t let him down. After 4500 mi. of hard desert and mountain play we let one of our pro motocross test riders try to break it. Two CMC races at Saddleback, one CMC MX at Carlsbad and one race at De Anza later, we retired the bike. It was starting to develop transmission problems. Interestingly enough, the bike was still competitive with all those miles on it. A second and third were taken at Saddleback, and first at De Anza and Carlsbad.
A few modifications were made to the YZ. A 3.2 gal. Vesco tank was installed and bolted to the stock mounts at the front by using longer 6mm cap screws. The padding didn’t even require change. It was necessary to slightly dent the top of the pipe for clearance around the petcock dummy plug though. A fuel filter was used between the tank and carburetor to keep the dirty Baja gas from causing carburetor flooding. The low octane Mexican gas caused considerable pinging so two base gaskets were used to lower the compression—end of ping. The double base gaskets also had a slight detuning effect on the engine’s power output. Not much, just enough to slightly tame it and make offroad use more pleasant. A Malcolm Smith aluminum skid plate was installed. It did a good job of protecting the engine cases but didn’t help the low-slung headpipe any. It’s full of small dents and scratches but engine power doesn’t seem affected by them.
Lots of time was spent trying to jet the richness out of the bike. It was finally worked out with expert jetting advice from Gil Valencourt, owner of Works Performance Shock Co. But we went back to stock jetting after White Bros, came out with a reed block spacer that cleaned up the running with stock jetting.
Some fiddling with different controls took place during the time we had the 465. The first change was the too-short shift lever. A folding International Motor Sports unit worked much better and it’s a little longer. The throttle was changed to a Gunnar Gasser straight-pull and a Terry Cable hooked the parts together.
Most of the plastic parts were left alone until they became ugly or broken. Most pieces were replaced once, with stock parts except for the front fender. We used a Petty on it.
Almost all of the parts on the YZ held up well. The handlebars are the exception. They are the right bend but the wall thickness of the tubing isn’t enough and they bend easier than they should. They were replaced with O’Neal stainless steel OW bend bars that’re filled with plastic balls to absorb vibration.
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The pipe and mounting brackets went the distance. The silencer worked fine until the packing burned out, then became too loud. We drilled a 3A in. hole in the back side of the shell, jammed the cavity full of fiberglass mat strips and plugged the hole with a steel press plug, available from any hardware store. It in effect made the unit repackable. Later in the year the unit was replaced with an Answer Products DG rebuildable aluminum silencer which is also lighter and quieter.
Tires were a big expense during the year. The big YZ eats rears like they were made from cheese. And trying to get all the power to hook-up isn’t possible with a tire smaller than a 5.10-18. Eighteen rear tires were worn out during the year. Experimenting with different sizes, brands and models took a while. Dunlop’s 5.10-18 K88HT put the power to the ground well and lasted a reasonable amount of time. We stuck with K88HTs for several months. When Metzeler brought out a new open class rear tire, a 150/80-18, we tried it. The 150/80 is wider, heavier and has bigger, wider knobs than a 4.50 Metzeler. It’ll tame the back of any open class motocrosser. Wheelspin is replaced with traction. It sells for around $80 but lasts almost twice as long as any tire we tried. The last five months of the test we didn’t use anything but a Metzeler 150/80. It’s worth the money.
Front tire choice was easy. A Metzeler 3.25-21. The best off-road tire around. The 3.25 Metzeler isn’t any wider than a 3.00-21 Metzeler, but it is 1 in. bigger in diameter. The larger diameter means rocks are farther from the aluminum rim. Riding on a flat is easier with the larger front tire also; the tire wraps around the rim helping protect it. Nine 3.25s took the 465 through the test year.
Rear sprockets are a problem item for most off-road riders. Newer bikes mostly have aluminum rear sprockets. The one on the YZ, like other bikes with aluminum sprockets, lasted about 600 mi. That’s not very long for an active desert rider. Fortunately, there’s another way. Yamaha’s TT500s use steel rear sprockets, and they’ll bolt right on. They won’t fit ’81 YZs however. The steel sprocket triples sprocket life and it costs about $10 less than the aluminum one.
Many people criticize stock Japanese air cleaners. The one in the Yamaha lasted eight months, more than a reasonable amount of time. And it did an effective job of filtering. When it simply wore out from being cleaned so often, it was replaced with one from DG. Not because the DG filter was any better, because we couldn’t find a dealer that stocked the original. The DG filter did an equally good job of cleaning incoming air.
Remember when riding a new bike required replacing all of the stock cables first? That era is past us. The stock Yamaha cables lasted for six months before we replaced them with more stock Yamaha cables. The excellent cable guides went the complete time without replacement but it was time for replacement by the end of the test.
Ten sets of grips were used during the 12 months. Rider choice naturally deter mined the brand and the YZ's main mar used Malcolm Smith/American Pro grip~ the whole time.
The Yamaha's incredible front brak took time to get used to. After endoing th~ bike four times, the last time 200 mi. be low the American border, we beveled th leading edge of each brake shoe to reduc the suddeness. Still the bike stopped to quickly on sandy surfaces for comfort The brake backing plate, shoes, springs and actuating arm were changed to 250C units. The 250G set-up let the rider relax yet stopped the bike well. The rear brak worked fine stock. Rear brake linings wen replaced twice during the test period.
We ignored the excellent Yamaha owners manual replacement times for th~ piston and rings, preferring to run the bik until it actually needed parts. It covere over 3000 mi. before the piston and ring~ were touched! Then a new piston brough the piston skirt to cylinder clearance dowi to 0.004 in., well within allowable toler ances. Still, the bike had gone through hel so we gave it a bore job. The rod, bearing~ and other moving parts weren't worn al though the bike had been ridden with 100 to 1 fuel/oil ratio several times whih in Baja. BelRay MC-1 was used the entir~ time. Mixing ratio was normally 60 to 1 but 100:1 was used in emergencies with out damage to the engine.
The transmission held up equally wel It went 3200 mi. before experiencin problems. During a Baja ride it suddeni started missing shifts. Still, it pulled dead Maico 450 over 40 mi. while actin up. The problem was a broken engag ment dog on third gear. The piece, aboL the size of a large bean, fell to the bottoi of the cases and started interfering wit the shift drum's movement, thus th missed shifts. Castrol GTX 20/50 fou~ stroke engine oil was used for transmissio oil during the test period.
Major and minor parts all were durabk The stock clutch and springs were still i: the bike when we returned it, and didn' need replacement. The stock hubs didn' crack, the stock spokes didn't break, th stock rims were still on the bike after year of tough use. Even more amazing wa the frame and swing arm; neither neede repair the whole time. No cracks, no bend ing, no problems. The seat started ou being a little firm and ended the test little firm. The foam didn't collapse, th seat base didn't break and the seat cove didn't rin
Saying we liked the YZ465 wouldn't b doing the bike justice; saying we loved it i more like it. Heading for Baja for thre days with little or no notice, and no time t prep the bike was no problem; just g ahead and go, the bike was reliably read: anytime. It never let the rider dow: once-not once. Not many machines rid den as hard as this one would be able t boast such a record.
