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Main Area => General GS500 Discussion => Topic started by: xunedeinx on July 09, 2011, 05:08:48 AM

Title: Strange oscillation? Or normal.
Post by: xunedeinx on July 09, 2011, 05:08:48 AM
This always happened, but kinda happened not as much (or i mentally thought it wasnt as much) after a carb tune.

Between 4750 and 5500ish, there is a repeating slow oscillation from the engine. It bugs me more then I think its bad, because you can feel the oscillating vibrations.

Has happened since I got the bike, dont think its bad, may have to do with the carbs (still) being out of sync?

they were pretty balls on after I synced them, they were bad.

-Justin
Title: Re: Strange oscillation? Or normal.
Post by: BrianKD on July 09, 2011, 07:36:09 AM
My '93 does that too. There's no power loss. The rpm's don't wobble. It's just a:
"HmmmmMMMMMmmmmmMMMMMMMmmmmMMMMMmmmmMMMMmmm" sound.
Right? I don't know if it's normal or a sign of problems.
Title: Re: Strange oscillation? Or normal.
Post by: joshr08 on July 09, 2011, 07:41:45 AM
squeeze the gas tank with your knees and see if it goes away
Title: Re: Strange oscillation? Or normal.
Post by: xunedeinx on July 09, 2011, 08:00:58 AM
Quote from: BrianKD on July 09, 2011, 07:36:09 AM
My '93 does that too. There's no power loss. The rpm's don't wobble. It's just a:
"HmmmmMMMMMmmmmmMMMMMMMmmmmMMMMMmmmmMMMMmmm" sound.
Right? I don't know if it's normal or a sign of problems.

Yea, that describes it pretty much.

Quote from: joshr08 on July 09, 2011, 07:41:45 AM
squeeze the gas tank with your knees and see if it goes away

Nope, im usually latched onto the tank pretty good anyway, keeps pressure off my wrists and makes back feel better.
Title: Re: Strange oscillation? Or normal.
Post by: lucifer_mr2 on July 09, 2011, 11:50:37 PM
Does the chain have any binding links in it? After a shop used a chain breaker on my chain there was a link that didn't like to move much, but I only really noticed it when riding in a very small window of speed. Rest of the time I couldn't find it.
Title: Re: Strange oscillation? Or normal.
Post by: Janx101 on July 10, 2011, 03:18:16 AM
not a long time rider but mine does exactly the same vibrate hum .. I think its just the natural harmonic vibrations of our particular powerplant .. Every engine on the planet has its own frequency of odd vibration i think? .. I drive 3 different trucks at work for example and they each have their own little rev range hum .. Used to have a 5 litre v8 ute and it had its own one .. So i dont think its just the engines i operate.

I think i remember seeing a video of a race engine being prepared and they were making micro adjustments with drilling and metal slug weights ... To the harmonic balancer on it .. To minimise any vibration .. Maybe f1 teams can eliminate it but who has that kinda cash?

Of course i could be a completely wrong gumbyhead and its some easily adjusted thingy .. But i reckon its natural :thumb:
Title: Re: Strange oscillation? Or normal.
Post by: mister on July 10, 2011, 02:59:21 PM
Mine has a harmonic hum in it somewhere. can't remember what rev/gear combo. But it is there. I'm now used to it and don't notice so I cannot tell you where it is.

Michael
Title: Re: Strange oscillation? Or normal.
Post by: andrewf on July 11, 2011, 07:09:16 AM
i have one too, around 100kmh in top gear so 5000rpm-ish. it's mildly annoying but if it's common then i'll stop worrying about it.
Title: Re: Strange oscillation? Or normal.
Post by: scratch on July 11, 2011, 09:24:00 AM
Is it a sound, or a feeling?

If it is a sound, it's normal.

If it's a hesitation (not a surge), it's the factory slightly-lean carburation.
Title: Re: Strange oscillation? Or normal.
Post by: BrianKD on July 13, 2011, 12:25:24 PM
It's just a sound.
Title: Re: Strange oscillation? Or normal.
Post by: Coccyx on July 13, 2011, 02:55:02 PM
Normal.  happens at a certain RPM regardless of gear/speed, it's just the frequency it resonates... like if you hum while using your vacuum and hit the right note your head does the same thing lol.