What's causing the engine vibration at 90kmh plus?

Question

I have a Honda Wave X 125 cc moped-style bike. Made in Thailand. It's new. It gets this nasty vibration in the engine above 90 ks. It should do up to 115 or so smoothly, but there's something wrong. Now, I took it to the Honda joint where it's under warranty and they say 'nope it's normal'. It most certainly is not normal . You can feel it right through the bike and the engine sounds rough too. What are some possible causes and what's my next move? PS The bike is tuned and the gas is right. The mountings are fine.

Answer 1

Get a sport bike thats designed to go fast

Answer 2

could be a poor design, out of balance.

could be a worn bearing.

could be the fact it was made in Thailand.

You're absolutely right!, you don't think:)

have you ever heard of bearing wear 'flat spots' during transit? i guess not, It is caused by the ocean tidal system, these bikes are packed into a container and loaded on a ship, a ship that is subject to oceanic motion, this causes bearing in machinery (including your rice burner) to move back and forth ever so slightly in the same position, the adverage container ship will suffer over 12,000 of these movements a day, times that by the number of days it takes to get to the US (around 5) so now you have 60,000, that is 60,000 movements in one position.

now tell me it has no effect?

Answer 3

I agree with Kelly on this one.  If the chassis doesn't have any cracks or loose motor mount bolts, then it's most likely either a chassis bearing, or an internal bearing.  

Since it's at a specific RPM, it's harmonic.  You can isolate it somewhat by seeing if it engine rpm makes a difference, or if it's chassis speed.  

This is tougher with a scooter without a manual clutch - if it's got a manual clutch, get it up to the 'buzz' zone, pull in the clutch and allow the engine rpm's to drop - if the vibes are still there, it's something in the chassis.  If the vibration goes away, it's internal.

Without a manual clutch, you might still be able to do it using neutral (if it's got it) and by turning off the bike, but it'll be tough.

Believe it or not, even BMW has worn/bad parts on new vehicles.  ALL major motorcycle manufacturers have had recalls in the past few years due to parts failures on various models.  Of course it's possible, or you wouldn't be having a problem!