If your favorite restaurant tomorrow starts offering a new dish, you might be tempted to try it.

The same phenomenon and thought process exists in mutual funds, and it was proven last week when two big-name fund firms rolled out new offerings that represent a departure from their usual lineup. Wasatch Advisers announced the opening of its Strategic Income fund, while Janus Capital Management unveiled Janus Advisor Long-Short, which will be managed like a hedge fund.

News of a new fund from either company tends to be greeted with excitement, as both firms have a history of starting funds that get off to a good start. Moreover, investors love being in on the ground floor of a fund, especially because the new fund phenomenon purportedly gives issues an extra pop.

But the newest issues are head-scratchers. Wasatch has a terrific record on stocks, but zero reputation for running fixed-income portfolios. Janus is at its best when the market favors growth, but now is creating a fund that times the market and avoids growth stocks when they are out of favor.

In each case, while the new funds are driven by research, the addition smacks of marketing, an attempt to stem outflows by filling a new niche.

During the bull market of the 1990s, firms routinely expanded past their core competency, so that they could lay claim to being a one-stop shop. They’ve been closing laggards and refocusing on what they do best ever since.

Investors can’t just assume a good firm’s newest offering is a winner.

The investor needs to approach the new fund a bit like a baby bear; it may look cute and cuddly, but it could have a vicious temper.

The question is whether management’s skills are transferable from one arena to the next, and that’s hard to tell, says Jerry Tweddell of Tweddell Investment Management in Sonora, Calif. who follows new funds closely because he believes start-up issues have a bit more pop in the early going.

Adds Thurman L. Smith of the Equity Fund Outlook newsletter: With a new fund that invests in a way the firm hasn’t really done it before, step back and let some numbers come in before touching them. Don’t be tempted too quickly.

Indeed, compare the new funds to their existing peers and take a best of breed approach, making your pick from the top of the list of available funds.

It is hard to project a new fund into that group, just because management is adept at running funds with a different style. After all, if management was brilliant at running funds in their new style, they might have started doing it a long time ago.

If they were opening a fund similar to what they do best, taking a chance makes sense, says Jeff Tjornehoj, research analyst for Lipper Inc. But exceptional skill in one area doesn’t mean someone is exceptionally skilled in others. If a new fund makes you scratch your head and wonder `Are they good at that too?’ you shouldn’t buy until that question is answered over time.