My son got a taotao 125d for Christmas. It starts, idles and runs good. After a couple of minutes of riding at low throttle, something is making a loud, brief grinding noise that sounds like it is coming from the engine. When it does it, you can feel it in the seat. It only lasts for a second, and it does it every couple of minutes. I have taken it to the dealer three times, but they have found nothing yet. Their first thought was the chain was too short and too tight. They fixed that, but the noise still happens. Any ideas?

 

Welcome to the forum 150cc

My Jetmoto 125 has a heavy kind of vibration at about 3/4 throttle.. It rattles the plastic and feels like a engine problem.. The reason mine does it ( I think) is the engine is mounted at only 2 places.. They sort of hung the engine in the frame like its mounted in a Honda 50..

Id start by checking the engine bolts..

 

This is a very clear brief grinding noise at low throttle.

 

Does it do it when its moving?

 

Only when in gear and moving.

 

In neutral.. no noise?

 

does it have forward and reverse?

 

No noise is nuetral. It does have forward and reverse.
I have been able to get it to make the noise with it in forward on jack stands. I haven't tried it in reverse.

 

If its safe.. try it in reverse.. maybe we can isolate the noise to one gear/shaft..

 

The dealer replaced the engine, problem solved.