Husqvarna 510te

HUSQVARNA 510TE

CYCLE WORLD TEST

YOU THE LIGHTEST, MOST NIMBLE BIG'BORE THUMPER BUY

BY NECESSITY. A FOUR-STROKE Single can't help but be heavier than a two-stroke of the same displacement. A four-stroke does, after all, have a lot more parts. Even so, four-stroke Singles don't have to weigh 30 or 40 pounds more than comparable twostrokes. But somehow, they always do. And the reasons why usually have something to do with engines that seem slightly overdesigned. and with cost-cutting measures that designers take when deciding on the material for a four-stroke's frame, swingarm and other weighty components.

A better approach. some people think, would be to first design a four stroke engine that is as light as possi ble, and install it in a proven moto cross or enduro-bike chassis. The end result would be an unsually light. good-handling and competitive four stroke dirt bike.

That's more or less what Hus qvarna did when designing its three hike line of tour-stroke dirt Sin2lesthe 5 1 OTX motocrosser. the S I ()TC cross-country, and the 5 lUTE en duro. the hike you see here. The TE's performance in the woods and hills

seems to hack up the theory that a thumper built specihcallv to he light can handle competitively with a twostroke. The way that the TE unravels woodsy trails is sheer delight, at both high and low speeds. Steering is quick and accurate, and the front wheel doesn't skate or try to run wide in turns: and, unlike other four-stroke Singles. the TE doesn't have a top heavy feel. All in all, it's the most nimble four-stroke dirt hike we've ever ridden.

None of this a2ilitv has come at the expense of engine performance. ei ther. The 5 tOTE makes almost per fect enduro power that starts pulling strongly right from idle and increases in a flat, uninterrupted climb all the way to maximum rpm.

To accomplish these marvels. Husqvarna had to build an engine that is as unusual as it is light. For all intents and purposes. the 5 1 0 motor is simply a four-stroke. single-over head-cam. fiur-valve top-end bolted up to a typical Husqvarna two-stroke bottom-end. There are no counterhalancers or anything of that sort. and, in fhct, there isn't even an oil pump: the engine sump is dry, with the two quarts of lubricating oil car ried onl~ in the transmission and clutch cavities (dry-sump engines usually have a separate oil tank or employ the bike's frame as an oil res ervoir). Oil is transported to the top end solely by the cam chain. which picks up lubricant from the clutch case on the left side of the engine and slings it onto the single overhead cam and the two fbrked. roller-tappet rocker arms. Excess oil is then carried back to the clutch cavity by the re turn side of the cam chain.

Lubrication for the piston. rod and crankshaft is provided via three 3.9mm holes drilled through the left side of the cylinder about mid-stroke. The piston's upward movement sucks oil mist through those holes from the cam-chain cavity, thus oil ing the vital parts. As the piston moves down, crankcase pressure pushes excess oil through a single petal reed valve in the cavity's bot torn, returning it to the clutch area.

Such innovative thinking has pro duced a 5 1 0cc four-stroke engine that weighs just 78 pounds complete with carburetor, kickstarter and shift lever (hut with no oil). That's 15 pounds lighter than either an `84 Honda XRSOOR or Yamaha TT600 engine. The Husk~ four-stroke also is around 2 inches shorter in overall height than the Japanese engines. mainly the result of using a small. two-stroke bottom end. Indeed, the six-speed transmission is the same as used in Husky's 500XC. the primary gears are identical to the WR400's. and the clutch plates are standard Husqvarna two-stroke items. The clutch basket and clutch springs. however. were designed just for the t(~)U r-stroke.

This engine first appeared in 1984 accompanied by lots of fanfare-hut lots of problems. as well. Marginal ig nit ions, slipping clutch es. quickly worn valve guides. and problems with overheating and carhuretion im mediately earned the Husky fourstroke a had reputation that prompted a factory recall. But for 1985. there are improvements in all those areas. New bronze valve-guides promise longer life, a new ignition makes a stronger spark at kickstarting rpm. stronger clutch springs prevent slippage. longer cylinder fins better dissipate the heat, and a 40mm I)eII'Orto carh-minus an accelerator pump-replaces last year's 36mm pumper.

According to Husqvarna. these changes are supposed to eliminate the reliability problems and hardstarting nature of the `84 models. With only 500 miles on our test bike as this is written, we can't comment on long-term reliability: all we can say is that our 5 1 OTE has suffered no major mechanical glitches so far. As for ease of starting. however, the bike still needs help, for lighting the 5 1 OTE's tIre can best he described as a kick-and-hope proposition. During a two-day. 300-mile outing. our test bike only started easily twice. The rest of the time. I 5 to 50 kicks. or a steep hi!!. were required to get the en gine running.

(`arhuretor jetting is the culprit here. althou2h youd never know it by the way the hike runs alter it is started. We ultimately cured the problem for a mere S I by swapping the stock No. 70 choke jet for a No. 65. replacing the No. S'S pilot jet with a No. 52. and by installin~ a lighter float (10 grams vs. 14 ram~ tbr the stocker). We got that jetting infl.rnia tion Irom the people at Ron Wood Racing Products(755 W. 17th Street. Costa Mesa. Califhrnia 92626: [714J 645-0393). who not only had the cure but distribute the necessary Dell'Orto carb parts. as well.

With these carh modifications. the Husky is no more cantankerous than any other big ftur-stroke Single. and starts first kick much of the time-if the rider stands on the left side of the bike and kicks with his right fhot. transmission in neutral, no throttle. Trying to start the bike while seated doesn't work: your left heel hits the shock spring and your toe often slams into the footpeg.

Once running. the engine is cleanrunning and predictable. never surg ing or coughing or balking in any way. It does emit a lot of vibration at idle and mid-range rpm. hut smooths out remarkably at high revs. If the 5 1 OlE is ridden on smooth ground or a paved road at a fairly steady rpm. the vibration can he tiring. But when negotiating the woods or hills that are typical of enduro-tvpe riding. the vi bration is not bothersome.

And it is in those woods where the TE shines. Its motor is so torquev that it will easily pull a gear or two hi~zher than the ideal one in practi catty any situation. That allows the rear wheel to maintain good traction on slippery ground and makes climb ing those slick, rutted. near-inipossi ble hills much easier. And when trac tion is good. the TE can crawl up steep hills at a walking speed without stalling, spinning the rear wheel or trying to loop. A snail couldn't get up a killer hill with much more precision and control.

When a fhst enduro section pops up. the TE's engine will propel the hike above 90 mph in sixth gear with out much pain, although it does re quire a halfofa mile or so to get corn pletelv wound out. Stopping the 5 10 from high speeds is no sweat, either: the large brakes work better than those on any previous Huskys we've tested, even though they aren't me chanicallv different from those on re cent two-stroke models. The dual leading-shoe front brake is powerful at high speeds without being grabby

at low speeds: and even though the rear lacks feel and requires a lot of lever pressure. it does an adequate job of stopping.

When wat~r gets on the shoes, though. the brakes go away alto gether and don't return until after they've been dragged as you ride along the trail. Stopping part way up a steep hill can be a problem. too: All dual-leading-shoe front brakes work poorly going backward, and the TE's are worse than normal in that respect. Turning the bike sideways is the only safe way to keep from rolling back ward on the side of a hill.

Aside from that, we had few real complaints about the 5 tOTE. One was that the clutch would sometimes make horrible clanging noises when being slipped repeatedly on a steep. difficult uphill. The clutch never slipped, but the freeplay at the han dlebar lever would increase signifi cantly. The other gripe concerned the dual-pipe, dual-silencer exhaust sys tem that not only adds unnecessary weight to a bike designed specifically to be light, but also is routed outside the dual shocks in a way that makes the TE ridiculously wide in the mid section. Consequently, the only way you can stand on the pegs is to as sume a bowlegged position. And al though we found a workable solution (see "The Pro-Circuit Touch," pg. 62 ). the problem shouldn't have been there in the first place.

Probably, that exhaust-system configuration is a by-product of Husqvarna's desire to use as much of its two-stroke chassis as possible in

the design of the four-stroke. The TE's frame is simply a two-stroke model slightly modified in the area above the carburetor to provide clearance for the high-mounted 40mm Dell'Orto: and the riding posi tion and control placement are typi cal Husky-the rider sits high on a firm seat, the handlebar is low and wide for good control in corners, and the seat-to-footpeg distance is longer than on the Japanese thumpers.

So is the TE's suspension bor rowed from the two-strokes. The front fork is essentially the same Husqvarna-built unit found on the WR models, and the twin-shock rear suspension is the tried-and-proven Ohlins arrangement. Both ends of the TE work smoothly and effectively, although a couple of our test riders thought the fork felt a bit harsh when hitting smallish rocks at speed. And, also true to Husky form, the fork seals started leaking within 400 miles.

Neither is maintaining the 510 much different or more difficult than on the two-stroke. The engine can be plucked out of the frame just as eas ily, and the oil can be changed in a snap. The carburetor is easily accessi ble, and removing the cam cover (for adjusting the screw-type valve adjust ers) and cylinder head (for piston or ring work) is a painless operation.

uying~'aHu~qvarna 51OTE might be more difficult than doing the maintenance, however. With an ask ing price of $3195, the TE isn't meant for everyone. Rather, it is a se rious, four-stroke woods racer for the rider with a fat bank account. And,

like other European-built racebikes, the Husky requires a bit of set-up by a knowledgeable dealer or owner be fore hand.

- Buta serious enduro rider proba bly won't mind spending a couple of days and a few extra bucks to get the TE properly set up. Because it would take a lot more time-and, in the end, money-to make any of the Japanese four-stroke Singles as light and com petitive as the 5 1 OTE. Despite its faults, it's the best woods thumper there is.

HUSQVARNA 500TE

$3195

Husqvarna Motor Co, Inc.