Your ATV has a 686cc so it should be a clone of the 700 yamaha motor which is also a 686 not there older 660.

 

The plastics more favor the 660. And, the cylinder head and valve cover favor the 660 also. The 700 engine pics Ive dug up look completely different.

 

Well, the 660 is a 5 valve design, while the 700 is a 4 valve. 686 was a common big bore for the 660. Yamaha is the only manufacturer I know of that really uses a 5 valve design to any extent.

 

That makes sense.

 

That is the BIGGEST Chinese quad I've ever seen .

 

And the Yamaha 660 had a pull start , the Yamaha 700's do not .

 

Well I'm getting a loud clunking on decel through the clutch/pulley system. So far this quad has not been very reliable. It has a new head, new cdi, and working on a slew of new clutch parts. Bahhhh Total mileage sits at 150.

 

Took her out to the ATV park this past weekend. Beat the living **** out of it. Lots of clay mud, and 4wd. The end result when running 5 psi in cheap **** china tires: Rode about 3 miles back to the truck like this.

 

What did your family member pay for it? I see list price is $6299. For that price I'd have bought a Honda Rancher. I'd guess though that he paid much less.

 

Though I never asked specifics.....I believe he paid around 4k new. Once I got it, I inquired at the atv dealership where it was purchased and they said they sold it way under list because it was stated to have sat in a shipping container for an extremely long time (for whatever reason) and the manufacturer discounted them and said "as is" don't call us for warranty stuff. So the dealership passed on the savings to the buyer. The dealership got a few of them, and said a couple had leaky freeze plugs before even being sold. Apparently just a common occurrence on these engines.