For a guy who knows practically nothing about cars (the blue stuff is windshield-wiper fluid and the green stuff is transmission fluid, right?) and even less about motorcycles, Harley-Davidson (NYSE:HDI) has always been something of a safe haven -- the signature look and sound of those monsters guarantees that there's at least one vehicle I can identify from a distance.

Well, Wednesday's earnings release is going to have a lot of people thinking long and hard about whether Harley-Davidson can be any sort of safe haven as a stock.

Although the reported results weren't disastrous -- revenue up 6%, EPS up 13% -- management sharply curtailed guidance. Instead of the mid-teens growth expected for 2005, cutbacks in production and shipments will bring '05 growth in on the order of 5-8%.

Given the fact that sales at the retail level were down about 1% through March, supply and demand for bikes seems to be nearly at parity -- which flies in the face of management's stated philosophy to always have demand outstripping available supply. As a result, the company intends to produce 10,000 fewer bikes for 2005 and is now targeting shipments of about 329,000 bikes.

Not surprisingly, the news brought both a swift drop in the stock (nearly 17% as of this writing) and a chorus of analysts questioning the long-term outlook for the stock. Of course, many analysts back in the early '90s were doubting that Harley-Davidson could ever get back on its feet, and if investors listened to them then, they missed out on quite a run.

On the plus side, Harley-Davidson has an incredible brand, good margins, good return on equity, and reasonable debt. What's more, cash flow is still pretty good, though a one-time voluntary contribution to retirement benefit plans lowered the number for the first quarter.

On the negative side, you have a company that basically sells only one type of product, and a pretty expensive one at that. What's more, the slowdown in retail sales raises the specter that pent-up demand has been satisfied and that there won't be enough new buyers to justify that high-single-digit production growth target.

Finally, insiders have been selling this stock pretty regularly -- stretching back into 2004. While there are plenty of reasons for insiders to sell that don't necessarily put the company's fortunes in a bad light, when you see a long string of sells without a single interruption of an open-market buy, that doesn't look good.

So what's an investor to do these days? Well, it all centers on whether or not you believe management when it says it can continue to post high-single-digit production growth and mid-teens earnings growth beyond 2005.

If you believe in the long-term demand for hogs, the current price isn't too bad for a mid-teens grower with great brand equity. If you don't believe in the ongoing demand picture, then you certainly shouldn't own the stock.

And if you're like me and really don't have any idea at all, your best bet is to probably stand on the sidewalk and wait to see a little more strength in that retail sales channel before taking the plunge.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).