There isn't a rule per se dealing with bumping a thread in the informational side of the forums in terms of only 1x per every 24hrs, etc., unlike the PX which has specific rules in that regard.
If it has been a while (like a couple days) without any responses to your OP, then I'd say its ok to just drop a post something to the effect of "Still hoping for some info on this topic. Anybody? Bueller? Bueller?" and see if that helps generate any input.
Like Blackout said though...if it isn't getting any responses...something is up as in its a dead horse that's been beaten, revived and beaten to death one many occasions.

Got a link to the topic you are concerned about?