Strong vibrations at 3500-4000 rpm

[mikitio]

Hello everyone,

Excuse my English, I am Spanish and I am using Google translator.

My name is Luis and I have a Stelvio 2008 with 43 thousand kilometers.

I would like your help with a problem I have on my bike.

Suffer a strong vibration moving between 3500-4000 rpm, are not the normal vibrations of our engines. These vibrations begin on the handlebars (3500), continue on foot (3800), returning to the handlebar (4000) and then seems to decrease, but if I keep up revolutions I feel the vibration on the feet.

I've tried just about everything I could think of:
- Tighten motor mounting screws, so good both outside and under the fuel tank.

- I'm synchronized cylinders and control valves, so good.

- The tires are in good condition.

- The rear wheel has no strange movement.

- The suspension seems fine.
I put the bike on the center stand, I put 3rd gear and have accelerated to reach 3500-4000rpm and no vibration producien, which means that only happens when the bike is moving or standing with wheels on the ground ( in this situation the vibration is low).

I not know what else I can look.

Well, if someone has suffered these vibrations (much more sensitive than normal) and can help me be very grateful.

Greetings to all.

[lucian]

Are you running the stock exhaust? Have you had the flat tappets inspected?

[Seamaster]

That means only when engine is under a load

[Wayne Orwig]

In the US, they put mirrors on the bike that have the turn signals in them. They aren't very good, and tend to vibrate a LOT. That adds to the handlebar vibration.
You likely do not have those bad mirrors, but I mean that you may want to look for vibration in other things. Loose mirrors, etc.
Have all of the motor mounts checked. Especially the mounts on the top of the heads under the fuel tank.

On a trip last week I started to get a buzz and vibration, that turned out to be a loose exhaust clamp.

[jabberwocky]

I don't know how severe the vibrations you're talking about are, but that's exactly the range where my T3 with 89mm bores is least happy. At 4k it becomes super smooth. 3700 is about the worst, as far as vibes go.

[Triple Jim]

Could it be a failing universal joint in the drive shaft?

[Tom H]

My '04 Cali EVT gets a vibration in the same range in 5th gear probably in the other gears as well, just most noticeable in 5th.. That puts it at about 80mph. Once over 4000, it smooths out. Still not as smooth as 3500rpm though.

The vibration is in the engine or trans. Seems like engine as it feels like I'm about to throw a rod out the block. Then it smooths after 4000rpm.

Tom

[MLR]

It wouldn't hurt to make sure the tires are balanced correctly; it could be a broken belt in one of the tires as well.