By: Chris

Chris — Mon, 23 Aug 2010 08:44:38 +0000

Wow. That’s got to be the longest comment we’ve ever had on Bike EXIF, Sven! But thanks—it’s a great insight into the vintage motocross scene and a salutory warning to potential buyers of works bikes!

By: Big Sven

Big Sven — Mon, 23 Aug 2010 08:22:02 +0000

Nice looking bike, but the only real good thing about it are the Ohlins shocks. If that’s a standard engine it WILL break. The rocker arms snapped like glass and there was something seriously wrong with the lubrication system and the gearbox shafts bent under full throttle, causing teeth to strip from the cogs. The fit of the various engine-parts wasn’t good, you needed to strip the engine and check and mod it as best could before ever taking it out on the track, cylinders were often found to be leaning over, not square to the cases, for example, and the conrods could be bent (as well as being 2-3mm too long for effective power-transfer). Racing engines they were not. Sten Lundin and Bill Nilsson had been looking at uprating a CCM, wanting to use the Husqvarna 5-speed box as many tracks on the continent had very fast straights and gearing for the entire track with a 4-speed wasn’t easy. That project ended when Bill’s son, keen to race a big 4-stroke in the GP’s, was killed on his factory 125cc Yamaha. Seeing the new Yamaha motor Lundin thought he was onto a good idea, but it made him go grey overnight! I’ll not forget the day up at a race in Älvängen, north of Gothenburg, when all 3 of his bikes stopped at the same time, all bellowing oily smoke. “Och det var inte första gången DET har hänt – And that’s not the first time THAT’S happened,” he growled, stuffing his hands even deeper into his pockets. Every component in the engine broke, and by the time they got it reliable enough to seriously race NOTHING inside the cases had ever seen the shores of Japan, but had SoCal or Hedlund written all over it. But they were still on the edge and many parts needed regular replacing. A local ‘born again biker’ bought one of Åberg’s practice HL’s and blew the gearbox first time out. He went white in the face when told what a genuine replacement cost, and bought a standard box instead. He also saw how expensive the rest of the engine internals would cost to hold in trim, and not long afterwards sold the bike off. Moral: NEVER buy an ex-works special, and certainly not a 4-stroke. (I once bought an ex-works 4-speed 360 HVA engine, and it snapped the gearbox shafts off like carrots. I later found out the factory changed the entire gearbox every 3 GP’s! Well, it did produce 50bhp…) Many 4-stroke riders sold off their CCM’s to buy the HL, but were just as quickly trying to buy them back again when the tuned standard Yamaha engines broke like confetti all over the place, despite having the mods Lundin had devised to improve reliability. By the way, a local Gothenberg racer made about a dozen replicas in his garage, using genuine HVA and ex-works Yamaha parts sourced from ‘a couple of guys with connections’ (ahem…) using the profits to help buy a house, so there’s no guarentee that Swedish-sourced bike is a genuine HL, though he did a good job. Hallman drew-up blueprints for a dedicated racing engine, knowing the Americans liked big 4-strokes, but Yamaha vetoed it. The famed 3-valve head was a spin-off from this, he made various bits to show the Japs. The 3-valver gave a slightly better throttle-response and acceleration, but Hallman’s test-rider told me if it was his money he’d stick to the 2-valver. Hallman had designed his new engine with the cylinder leaning BACKWARDS, to improve the inlet angle for best performance, but to fit the head to the standard engine he had to bend the inlet to fit the carb into the frame, thus the inlet didn’t flow as well as his original design. I’m not a 4-stroke fan, but I raced a 4-stroke for 5 races in ’78, a HVA special with a Yoshimura-modded Honda 420cc XL350, but it got stolen and wrecked before I finished developing it. In retrospect, a waste of time, and cost a fortune to make – double what a new HVA cost. I should have saved my money. But it sounded good and after experimenting with engine-placement, swing-arm positioning, and springing, was beginning to handle well, luckily, as I had to ride the socks of it in the corners as it was slower than 390 HVA’s. The Rotax 4-stroke never took off for some reason, but there were a few slotted into HVA’s. Then salvation, one of the HVA engineer/racers slotted a Honda XL350 head on an old 4-speed HVA 2-stroke engine and soon afterwards we had the excellent HVA 4-stroke! I personally think Bill Nilsson was on the right track with his 5-speed CCM, there’s nothing wrong with pushrods, but mating the HVA gearbox to the CCM ment a new crankcase and that cost huge money, despite Hedlund offering to do it for cost. Bill used an idler-gear from the crank to the clutch, to get the right rotation (NSU did the same on their fabulous racers in the 50′s, their idler-gear also drove the camshaft). But. I’d dearly like to see Hallman’s 4-stroke engine design! I’m sure THAT was a right cracker!

By: lee

lee — Sat, 21 Aug 2010 16:46:01 +0000

Nice. But somethings on this dont look right.
77-78 Front forks with DLS?wrong position
seat sits a bit high over the tank.
Chain guide could have looked more period correct.
Fenders off a 78? White.
IMO. just sayin!

By: rich

rich — Tue, 13 Apr 2010 11:12:49 +0000

Indeed a classic

By: PeteP

PeteP — Mon, 12 Apr 2010 12:37:11 +0000

Always loved the HL500s. I have three XT/TT/SR engines in my garage. Time to get busy!

By: Glenn Edley

Glenn Edley — Sat, 10 Apr 2010 23:17:06 +0000

That would be one LOUD bike. Enough to shake the snow from the trees.

By: ddlee

ddlee — Sat, 10 Apr 2010 20:57:16 +0000

Mold tities still on the tires, that’s just not right.