left my bike out in the rain for about an hour yesterday and now its reving really high. when i start it it starts at bout 1.7 (where it sits normally) then steadily rises to about 3-4, when i put it in first it stays at about that, but it does go higher at times (highest its sat at is about 6). i'm guessing its not good for the bike, and it makes me look like a total reject as im sitting at the lights with the bike revved heaps. so what are some probable causes? how easy is it to fix? could this be a problem that fixes itself?