Virbration at certain RPMs Stella 4t

jkblaq · Post by **jkblaq** » Mon Jul 07, 2014 3:22 pm

Hi guys,
I took a little (20 min) ride yesterday and took on some pretty large hills. Since this ride, I have notice alot of vibration during low RPMs. For example if I am in 2nd and just cruising in the band, the engine vibrates much more heavily than it has in the past (only had it for about a month). But it also seems to happen while cruising in 3rd and 4th too.

After the ride I did a check of all the bolts and tire pressure and all seemed good.

Does this sound normal? Perhaps I finally got it up to temp with my longer than average drive?

Stilts · Post by **Stilts** » Mon Jul 07, 2014 3:35 pm

Are you sure it's the engine? Check the exhaust for cracks, especially the mounting plate. If there's a small crack there, it can make the normally quiet exhaust rattle like the dickens and make a whole lot of noise and vibration, especially in the lower gears. I just had mine replaced about seven weeks ago due to such a crack and noticed last night that the new exhaust is already developing the same thing!

jkblaq · Post by **jkblaq** » Mon Jul 07, 2014 3:42 pm

No not certain its the engine, I will have to check that out. Would the crack be obvious, is that the mounting plate under the foot area or at the engine? I did inspect the exhaust and it had no movement by hand but that would not rule out vibration at speed. I did suspect the exhaust at first but could not find anything on initial inspections. Sounds like I need to give a more thorough look.

Stilts · Post by **Stilts** » Mon Jul 07, 2014 3:59 pm

This is the bit I'm referring to.

Look at that part and wiggle the exhaust a bit. Check both sides. You'll see the crack if that's what it is.

jkblaq · Post by **jkblaq** » Mon Jul 07, 2014 4:28 pm

Wow. Thanks so much for the Pic! I appreciate the help, I will check tonight when I get home.

Neurotic-Hapi-Snak · Post by **Neurotic-Hapi-Snak** » Mon Jul 07, 2014 8:30 pm

I've noticed this, too. It's just the nature of a high RPM single cylinder engine. Certain RPMs create vibrations at certain frequencies that are "in-tune" with the rest of the bike and are more noticeable than others.

slotrod65 · Post by **slotrod65** » Tue Jul 08, 2014 4:06 pm

I would check more than the exhaust... I routinely work my way around the scoot tightening nuts and bolts. Nearly any part can shake loose. Lock tite is your friend here.

jkblaq · Post by **jkblaq** » Thu Jul 10, 2014 11:21 pm

Finally checked the exhaust and other miscellaneous nuts everything looks good. Must just be me, took a few more rides and commutes and still noticed the vibration but maybe Im just over analyzing it.

Tom · Post by **Tom** » Sat Jul 12, 2014 1:56 am

Pull down on exhaust too. When u dont have the vibrations a broken weld will be seated up high as if it isn't broken. Mine shook so long and was misdiagnosed till it finally broke off at the pipe. Also mine broke not where it's pointing there, but where the flat part welds on.. Genuine replaced for me and hasn't rattled a bit since.

Post by **ericalm** » Sat Jul 12, 2014 8:07 am

The other weak point in the exhaust is the collar welded on under the header. You would probably have other symptoms if that were the case.

Have you checked your tire pressure?

Is the vibration accompanied by a noise?

jkblaq · Post by **jkblaq** » Sat Jul 12, 2014 11:26 pm

Tire pressure is good, and no other abnormal noises. I guess one thing I did change was the gas I used. I went to a place that uses 10% ethanol, when normally I go to Shell and get the good stuff. But not sure that would do anything related to vibration. It really does not seem like anything abnormal now. Thanks for all the reply's.

Today, I replaced the clutch cable for the first time, not too bad. Just hope I tightened the nipple enough, does it stop turning when its tight? I couldn't seem to get it to stop turning.

Yalzin · Post by **Yalzin** » Mon Aug 04, 2014 6:39 pm

Just to throw in my experience, but I noticed that I had a vibration as well, particularly around certain speeds or RPMs.

Turns out it was the spring on my rear shock vibrating at those RPMs.

Mechanic suggested getting rubber inserts that will dampen the vibration. I'm not sure if I should do that, or replace the shock/spring.

Yalzin · Post by **Yalzin** » Wed Sep 24, 2014 12:07 pm

Turns out no auto parts store around here has any idea about those vibration rubber thingies the mechanic talked about.

Also - update! Seems my exhaust cracked along that same seam. Hooray Warranty!

hewl35 · Post by **hewl35** » Wed Sep 24, 2014 8:34 pm

[quote="Yalzin"]Turns out no auto parts store around here has any idea about those vibration rubber thingies the mechanic talked about.

Try looking at McMaster Carr website under vibration isolators.

Stilts · Post by **Stilts** » Wed Sep 24, 2014 8:40 pm

Yalzin wrote:Turns out no auto parts store around here has any idea about those vibration rubber thingies the mechanic talked about.

Also - update! Seems my exhaust cracked along that same seam. Hooray Warranty!

Told you so.

Yalzin · Post by **Yalzin** » Fri Sep 26, 2014 2:42 pm

I'll get some pictures of the length of the crack from the old exhaust soon enough. The new exhaust solved some of the worst of the vibration! (Though getting the shop's torque wrenches on the exhaust nuts was a PITA...)

Luckily, Donna is still musical - seems that my kickstand springs are vibrating and hitting against the exhaust. They did it with the old exhaust, seem to do it with the new exhaust. Hrm.

rondothemidget · Post by **rondothemidget** » Sun Oct 12, 2014 9:06 pm

I had the same problem. If I remember correctly, the engine would begin to vibrate around 25 mph in 2nd, 35 mph in 3rd, and 45 mph in 4th. It would smooth out above and below those speeds.
As it was just past the warranty, Genuine offered to do a complete engine tear-down, with me picking up the tab for an unknown amount of labor and them paying for parts. In hindsight, I should have taken them up on the offer as the engine crapped out about a 1,000 miles later.

kmrcstintn · Post by **kmrcstintn** » Sat Nov 08, 2014 12:42 am

the Stella 2T I had used to buzz more than a pissed off bumble bee! common due to the metal sheet construction without dampening materials...

Yalzin · Post by **Yalzin** » Sat Nov 08, 2014 5:43 pm

Exhaust - replaced (hooray)

But now...

http://youtu.be/i_gIhkUJ3uQ