Strange oscillation? Or normal.

[xunedeinx]

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

[BrianKD]

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.

[joshr08]

squeeze the gas tank with your knees and see if it goes away

[xunedeinx]

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.

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.

[lucifer_mr2]

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.

[Janx101]

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

[mister]

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

[andrewf]

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.

[scratch]

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.

[BrianKD]

It's just a sound.

[Coccyx]

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.