Sparks spray as Mark Daly grinds on a custom motorcycle frame that looks like something out of a science fiction movie.

Sparks spray as Mark Daly grinds on a custom motorcycle frame that looks like something out of a science fiction movie.

"It's for a show in Vegas next month," he says. "It's far sicker than anything I've ever done."

Which is pretty sick, or cool, considering the likes of Twister, a very long chopper in gleaming green and silver; Captain America, a low-slung, stars-and-stripes take on the Harley Peter Fonda rode in "Easy Rider;" and The Hammer, which Daley recently sold to Iceland billionaire Bjorgolfur "Thor" Bjorgolfsson for $175,000.

In his day job, Daley designs and builds one-off customs, customizes Harley-Davidsons and does Harley maintenance at his Thunderstruck custom bike shop in Medford. But once a year his passion turns to kids, in the form of the kid-friendly Thunderstruck Xtreme Bike Show and Street Party in downtown Medford.

They close the streets for vendors, food and a beer garden in connection with the annual motorcycle show, the 13th edition of which is coming Saturday. Last year the event raised about $12,000 for the Boys and Girls Clubs of Jackson County.

"We've raised as much as $18,000 some years," Daley says. "This year I'll be happy with $10,000. But all my sponsors have come forward again."

The event includes a display of Daley's custom bikes, exotic cars, face painting and ice cream for the kids, and it's free to the public. It costs $10 for motorcyclists to enter their machines, but most of the income comes from a donations and local sponsors.

There are classes for different motorcycles, from wild, full-blown customs to street Harleys and metric cruisers, or Japanese bikes. There's a class for vintage bikes and a lady's division. Daley says he expects maybe 100 motorcycles at the show, not counting his own.

He'll probably take about a dozen. But they're there for their ooh and ah value, not to compete for trophies.

"It's not to intimidate people," he says. "We want people to bring the bikes they ride. The guy who builds one in a garage, that's the one I admire."

Dennis Mollett, of Shady Cove, didn't do his in the garage. In fact, he invested about $20,000 in a new Street Glide Harley only to turn it over to Daley and company for another $20,000 worth of custom work. The bike is a black cruiser with faring and a theme that appears to be built around medieval battle axes with silver edges.

"There's not another bike like it," Mollett says. "It has a draw factor. Wherever I go, it draws the most attention."

Much like Sniper, the stretched-out dream bike Daley is building for that prestigious show in Las Vegas. Even half-done it looks like a sci-fi fantasy with its big Honda carburetors, exhaust pipes up front and a big disc brake in the middle of the rear wheel.

"I want it to look like a futuristic aircraft," Daley says.

And there's Twisted, a sparkling, green, 10-foot piece of eye candy with extended forks that's chrome everyplace it isn't green paint or black rubber.

There's even the Billy Bike. That's a Harley companion for Captain America. It's done up like the one Dennis Hopper rode to his fate in "Easy Rider."

Daley says he and a customer typically brainstorm a design, and both have to sign off on it before work can begin.

"They have to have an elegant presence," he says.

He says in real life, running a motorcycle shop is not much like the Discovery Channel's "American Chopper."

"We get along," he says.

Mollet says what he really likes about the show is the camaraderie and the fact it's a fundraiser.

He says, "It's for the kids."

Reach reporter Bill Varble at bvarble@mailtribune.com or at 776-4478