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futurelaker88's avatar

Why does my motorcycle sound different (almost like a loud fan or compressed air)

Asked by futurelaker88 (1595 points ) July 1st, 2010

hello, im new to motorcycles, and have NO understanding of mechanics (cars/bikes). I mean none. I couldnt tell you one part of the bike in terms of the engine, let a lone how to fix or diagnose a problem. Lately, ive noticed my ninja (which is a 2006 in PERFECT condition) has been sounding like a loud fan or compressed air is being released when i rev the engine. I dont remember this happening last summer. Ive owned the bike for about a year and MAYBE this is how its supposed to sound, but it just seems different. it almost sounds like hissing air and it is noticeable when the throttle is opened. I had the bike serviced at 500 miles. i did drop it once, and it barely caused ANY damage at all. perhaps this did some internal damage? how can I tell? It seems to run the same, and feels fine most of the time, it just sounds like its working harder because of the air sound. does anybody have any ideas as to what this could be? THANKS!!!

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11 Answers

ApolloX64's avatar

A hissing sound would usually point to a vacuum leak. Vacuum leaks often happen when rubber hoses wear out and crack, or even gaskets for the air intake or manifold start to wear out and weaken. Since you admit you have no experience, I would take it to a shop and get it checked out ASAP.

*Edit – It could also be an exhaust leak at the mating flange. Do you smell anything “off” about the bike when it’s running?

futurelaker88's avatar

@ApolloX64 do you think that maybe the hissing i am hearing is normal? is there supposed to be a sound like this with bikes at all? the only reason im asking is because the reasons you give seem like they might not partain to my bike as its so new. it had 72 miles when i bought it last summer, and the woman never took it over 40mph. so its seems unlikely that the hoses would be worn and cracked. Also, the bike was serviced last summer at the dealership, so i would say (or at least HOPE) that the gaskets would not be worn or weakened at this point. Im trying to listen to some videos of the bike on youtube and see how it sounds, i notice the air sound on other videos.

http://www.youtube.com/watch?v=WCfZ-vJ2Qeo

go to about 3 and a half minutes in this video. this is EXACTLY how mine sounds. maybe this is normal? i dont know lol. but do you hear the simultaneous HSSSSSSSSS along with the engine?

ApolloX64's avatar

That sound you’re hearing is air being drawn through the intake. Nothing to be worried about if it’s like that. Take it out and exercise it a little on the highway.

futurelaker88's avatar

@ApolloX64 by excercise…what do you mean exactly? do you mean “push” it? im afraid to take the RPMs past 8k. would going past be bad for the bike?

ApolloX64's avatar

Rofl. It’s a sport bike. Exercise it man, it’s not a baby, use it the way it’s intended. Don’t over-rev it by any means, but definitely run it easy for a bit on a regular road then pop over onto the highway and open her up nice and wide and let her run free.
*edit – When they sit, they stiffen up, especially if you didn’t start it up periodically over the winter, so you need to ease it up, then run it hard for a bit, then ease it down again. Just like exercising your own body, you start slow, speed up then cool down.
Sport bikes are made with a lot of tolerance for abuse and fun-running, so take advantage of it. It’s like buying a Corvette and then garaging it and using it for nothing but a showpiece. That’s not what it’s meant for, if it sits too long it’ll rot faster than if you ran it every day and looked after it.

futurelaker88's avatar

@ApolloX64 lol im telling you, im new to this! lol, it feels like im pushing it if i rev too high. im not experienced enough to have the “feel” for whats good and whats too far. at first i was keeping it below 5k. now to push it to 6 and 7 feel like im breaking it lol.

ApolloX64's avatar

lol I hear ya buddy. Just take it easy like I said, then push it a bit. What you’re hearing is the intake drawing air in for the fuel mix, entirely natural. So go have some fun and enjoy the weather.

futurelaker88's avatar

@ApolloX64 thanks man. i appreciate it

ApolloX64's avatar

NP, have fun with your bike and just ride carefully.

ipso's avatar

It’s your engine fan.

It comes on only when the engine coolant reaches about 220F, which may start to happen now that summer is here. You won’t hear a vacuum hose over that engine.

However, if the sound matches the engine revs, have it looked at. I doubt it, on that bike, but you may have dinged the pipe when you laid it down and compromised the head gasket or slip-on joint. Probably not.

SeventhSense's avatar

Now I want a motorcycle.

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