I would like to see a diagram for a mikuni fuel pump part# .MK-DF52-531 yamaha rhino 660.

It takes fuel, spark and compression to run. Check compression to verify within spec..

NO - Karen
from the specs below this engine is a 4 stroke engine you may wish to run it on a higher octane fuel but that is your choice
but no oil as it is not a two stroke engine .
http://www.atv.com/specs/yamaha/utility-utv/2006/rhino/660-auto-4x4/detail.html

The Rhino was released in 2004 and was offered with a 450cc or 660cc engine with a carbureted fuel system. The 450cc engine was based on the Kodiak 450 ATV engine architecture, and the 660cc engine was based on the Grizzly 660 ATV engine architecture. Both engines were modified for use in the larger Rhino chassis. In 2008 Yamaha upgraded the big bore Rhino to the 700cc fuel injected engine that was again borrowed from the Grizzly 700 ATV. Yamaha did not offer the 450cc engine size from 2011 to 2013. All engine configurations were single cylinder four-cycle designs, mated to Yamaha's Ultramatic transmissions. All Rhinos use an electronic speed limiter system to restrict the top speed of the machines to approximately 38 MPH (61 KPH So the answer is no, oil is added to 2 cycle engines.

sounds like the decompressor has broken

It could be your battery not being fully charged or possibly dirty fuel.

Worn or broken piston rings or warn valve guides. A compression test will let you know which one.

Semi-synthetic or Mineral oil, Don't use fully synthetic, it can make the cluch slip.

Go to bike bandit.com , it will give you a picture diagram of the comple engine, and transmission.