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Harmonic howl(noise) in Attak?


harmonic noise

Maybe Mr. Sled could find out from Yamaha eng. if placing weights on certain places on the exhaust pipes might help with this howlling noise at the lower RPM'S. I have a 05 shorty and the noise is very bad at between 4500 and 6500 RPM. :rocks:
 
If the noise was coming from the exhaust which I believe it is not you will hear it even more if you are not moving. I tell you this is not the problem. If you dont believe me take your belt off and run your sled at 4500 to 6500 rpm and all you will hear is a 4 stroke purring. The noise is coming from the track,skid & drivers combination and like others have said the tunnel could be resonating the sound even more. Tunnels have not changed much in design so I doubt that is the cause.
 
If the noise was coming from the exhaust which I believe it is not you will hear it even more if you are not moving.......[/b]...
Today I tested your excellent idea sled dog and ran the sled without the belt and the annoying hum is vibrating out of the tunnel . I also tested it on 5o mile ride today when going down hills and let off on the throttle the noise is gone so I know it is not track related...[[/quote]
 
trlbrkr said:
If the noise was coming from the exhaust which I believe it is not you will hear it even more if you are not moving.......[/b]...
Today I tested your excellent idea sled dog and ran the sled without the belt and the annoying hum is vibrating out of the tunnel . I also tested it on 5o mile ride today when going down hills and let off on the throttle the noise is gone so I know it is not track related...[
[/quote]

Same here. My Attak does it right at 5250 RPM. If I go up a steep hill it is at 5250 RPM at a slow track speed, or down hill at a fast track speed, same 5250. One thing I noticed was after a long wide open pull out on the lakes when the pipes got very hot it was way less until the pipes cooled back down.
 
Really! Well that surprises me actually. I can only go by what I ride our 05 makes the noise all the time louder at some speeds than other speeds. It seems to harmonize with the exhaust note at a certain speed and that is where it is the loudest. The noise on mine is directly related to ground speed so that is how I know it is track related. I also did the engine noise test with the belt off and all it did was purr. So two different sleds both with two different howling/noise related problems.
 
trlbrkr said:
If the noise was coming from the exhaust which I believe it is not you will hear it even more if you are not moving.......[/b]...
Today I tested your excellent idea sled dog and ran the sled without the belt and the annoying hum is vibrating out of the tunnel . I also tested it on 5o mile ride today when going down hills and let off on the throttle the noise is gone so I know it is not track related...[
[/quote]

This is true, the vector does not have this noise, and it is monoshock this year too.
It has to do with the inline 4 cylinder engine, the exhaust and tunnel. It is somewhere around 5000 RPM or so.
The motor give off vibes, which the exhaust and tunnel are sympathetic to. what the car manufacturers do is NVH or NHV (noise vibration and harshness) tuning, or lots of cars would have more noises too, especially 4 cylinders. They use stiffening ribs, sound deadening material and so on to tune out sympathetic and other vibrations.
Older hand built cars (Rolls Royce I think) used to do some of this tuning with a hammer, changing a piece of sheetmetals shape and thickness to do some of this type of thing.
I mean somebody with some thermal exhaust wrap, aluminum angle strips, or some heavy sound deadening material could probably solve much of this, if they had a couple of days to experiment.

would be nice to know if the white Knuckle or Excell exhaust changes anything too.
 
I had the same type of noise last year on my Vector, it was so loud I cound not stand to ride it. This year I put on a fully clipped 136" Rip Saw quite track on with external drivers. Noise is now gone.
 
Slush Monster said:
One thing I noticed was after a long wide open pull out on the lakes when the pipes got very hot it was way less until the pipes cooled back down.

I agree with Slush Monster & Tork. I too have noticed that after ripping up a forest road between 70 & 90 mph.....the sound is not as bad once you slow back down. But just give it a few minutes driving slower.....and the drone noise comes back. Tork's definition sounds on par from what I'm hearing from my sled.

I don't mind it when pulling into towns to get gas or food....because it sounds like you're riding on a "caged animal" ;)! Although.....I'm not sure if it sounds this mean to the other sledders! LOL! But driving on the trails........yeah.......it will get old real quick.
 
Vector1 said:
I had the same type of noise last year on my Vector, it was so loud I cound not stand to ride it. This year I put on a fully clipped 136" Rip Saw quite track on with external drivers. Noise is now gone.

Very important to note we are talking about 2 different noises.
Track howl, which is worse on the vector (I own one) but RX had some howl too.
And the harmonic on the Apex Attak (I own an apex)
(some RX 1 sleds had some harmonic as well as track howl)
This harmonic noise for the most part goes away much above 40 MPH or 6000 RPM, track howl does not react the same way.
I may not have the MPH and RPM exact, but you get the idea

The fact that the 06 4 cylinders are louder may have something to do with the exhaust change, which is they went from dual pipes to the muffler to single, I'm pretty sure
 
I removed the seat on my Attak today and found the plastic bottom of the seat is in contact with the tunnel ...I laid a cloth in there and took it for a ride...Voila ...Harmonics substantially reduced ...
 


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