well my friend bought a china quad mainly cause there wernt any name brand used quads that fit discription and price. its a 125cc p-65 from powersportsmax, not sure if its a good one or not but we made the mistake of rushing and riding it with the factory oil during our testing everything ran good, acceleration and speed were a little slow, but at full speed a really loud grinding, gear grinding ocurs but stops when it slows down a little. im guessing top speed on it is maybe 35 so when its at 33 or so the grinding starts. any help or tips are greatly appreciated

 

Welcome to the forum tjend!

Id call powersportsmax and see what they say..

 

Weird. I wonder if it isn't a resonance phenomenon. Maybe at just the proper speed something gets tuned up and starts shaking? I can't think of anything that would so abruptly change between 33 and 35 MPH other than a resonance of some sort.

What happens if you jack up the quad rear and run the wheels spinning in air. Does the same thing occur? Try applying some rear brakes to give the engine some load. Does this change anything?

You really need to be careful when doing tests like this - if the quad comes off the jack stands at full running speed you can do some serious damage to the surrounding environment. Tether the quad, and make sure the forward path stays clear, stay well away from rotating machinery, etc.

 

also, drain the oils and change them both. engine and tranny(i don't know if your axle is chained or shafted, so if shafted, take care of that also). looks for metal shavings. that'll be the clue to look for when it comes to damage. take advantage of any warranty that is offered for repairs/replacements.

 

Good thinking LE... my 125 vibrates a lot.. especially at high rpm...

 

yeah im not to sure but its just like bang screetching loud noise, then you slow down 1 mph and its fine, but ill work on it today and see what i can find. changing oil sparkplug cleaning carb out. are stock air filters on these things good ? and its chain drive. thanks