Recognise problem: whinying-rattling noise?

[elder]

Does anyone recognise this problem: yesterday, my BT125T9 started a loud (disturbing) whinying-rattling noise around at the back. The noise only presents itself when:
1. accelerating (eg from 10-20 mph)
2. above 25-30 mph with or without throttle

The funny thing is, I can't replicate the noise revving when stationary. I don't think there is something loose in the exhaust. I would have thought it was the drive belt except the noise does not seem to come precisely from there.

Any help appreciated.
elder

[hypojam]

Starter Motor Bendix May Be Getting Caught Up

[r08813]

I've got the same model.

2 things to look at

1. Is the airbox correctly bolted on? - there is (Should be) a bolt that passes through the lower part of the airbox, then through the rear mudguard and finally into a piece of metal on top of the Variator.

If the bolt is not there, you should be able to find the hole and fit one - careful about the length of the bolt as it can come out near the rear brake actuator.

2. check to see if the reed in the valve connected to the exhaust has broken

[elder]

I had a closer look on Saturday and have discovered the problem.

The top bolt of 2 (there is a further 2 bolts fixing the rear mudguard to the exhaust) fixing the exhaust to the scooter has sheared off.
The rattling noise was made by the now unbolted flange hitting the scooter when vibrated by the rear wheel in motion. Unfortunately, the bolt hole is now blocked by the remaining thread on the old bolt which is stuck. As far as I can see, I have 2 choices:
1. try to drill the old bolt out
2. have someone weld the exhaust permanently onto the scooter.

Any feedback? There is an old thread that had just this problem.
taishanowners.proboards41.com/index.cgi?action=display&board=garage&thread=1136907864&page=1

[Spaceprobe]

I had a similar noise and traced it to the speedo cable, put a few drops of gear oil down it and its fine.