The Yamaha Rhino 660 is one of the most popular side-by-side UTVs thanks to its rugged durability and ample horsepower. Since its release in 2004, thousands of outdoor enthusiasts have put this nimble and powerful machine to work around the farm, ranch, hunting camp, and off-road trails.
However, as with any machine that gets used and abused in rough conditions, the Rhino 660 can start to develop some common problems as it racks up the mileage. So what are the most common Yamaha Rhino 660 issues owners face, and how can you diagnose and fix these problems yourself?
The good news is that many of the common Yamaha Rhino 660 problems stem from easily replaceable parts and DIY maintenance items. With some basic mechanical skills and troubleshooting techniques, you can often get your Rhino up and running again without costly shop repairs.
In this DIY repair guide, we’ll cover the most prevalent Yamaha Rhino 660 problems owners report and provide tips to diagnose and fix these issues yourself. We’ll discuss:
- Troubleshooting starting problems with the starter motor and battery.
- Loss of power issues under load and at high elevation.
- Overheating problems and how to diagnose the cause.
- Troublesome transmission and clutch problems.
- Getting to the bottom of engine won’t start problems.
Let’s get started exploring some quick DIY troubleshooting and repair tips that can save Yamaha Rhino owners time and money.
Table of Contents
Diagnosing and Replacing a Failing Starter Motor
One of the most common issues Rhino 660 owners report is failure of the starter motor. This small electric motor is responsible for engaging the flywheel to turn over the engine when you turn the key.
Problems with the starter motor and related components can leave your Rhino failing to start or turning over very slowly. Let’s look at some troubleshooting steps and solutions.
Symptoms of Yamaha Rhino Starter Problems:
- Clicking sound but engine does not turn over when ignition engaged.
- Starter spins but flywheel does not turn.
- Slow cranking of starter.
- Starter engages briefly then disengages.
The first thing to diagnose is whether the issue lies with the starter motor itself, or battery and electrical connections feeding the starter.
First, check basic electrical items like:
- Battery – Check voltage and charge state. Should be 12V+ when fully charged.
- Battery terminals – Clean any corrosion and tighten connections.
- Starter relay / solenoid – Bypass to test if defective.
- Loose ground wires – Tighten chassis and engine grounds.
If the battery and electrical connections prove good, you can test the starter:
Starter Testing Procedure:
- Remove starter and bench test by applying 12V power directly.
- Mount starter back on engine but disconnect from solenoid.
- Jumper solenoid with screwdriver to engage starter and test.
- Turn ignition and listen for spinning sound if issue is in flywheel.
If the starter still fails to engage, it will likely need rebuilt or replaced. Some things to check internally on the starter:
- Brushes – Inspect length and spring tension.
- Commutator – Should be clean and smooth.
- Armature – Check for burned or damaged windings.
Replacement aftermarket and OEM starters are readily available for the Yamaha Rhino 660. Plan on about 2 hours or less for R&R. Just be sure to reconnect all wires and mounts properly.
With the battery, cables, starter solenoid, and motor in good shape – your Rhino should turn over strong when engaging the starter.
Loss of Power Under Load Issues
Yamaha Rhino’s are known for their responsive acceleration and robust power. But over time, lackluster performance can start to creep in – especially under load. Some common causes include:
Air Filter – A restricted, dirty air filter robs power by limiting air intake. The 660cc engine needs adequate airflow to make full power.
- Inspect and replace the foam pre-filter after every ride.
- Clean the paper air filter element periodically or replace after 20-30 hours.
- Use original spec filters to avoid premature wear from off-brands.
Spark Plugs – Fouled, worn, or defective plugs prevent proper ignition timing and weaken power.
- Inspect plugs every 20-30 hours for fouling, electrode wear, and gap.
- Replace with OEM rated spark plugs gapped to spec.
- Use resistor type plugs to avoid electrical interference.
Compression Loss – As top end wears, loss of cylinder compression reduces power significantly.
- Perform a compression test annually to measure cylinder pressure.
- Look for at least 100 psi per cylinder on a healthy motor.
- Rebuild top end or replace piston rings if below spec.
Fuel Supply – Any fuel delivery issues will lead to power loss.
- Make sure gas is fresh and the carb isn’t gummed up.
- Check for cracks in fuel lines or vacuum leaks.
- Clean carburetor jets, ports, and replace any worn gaskets.
Elevation – High altitude=less power due to loss of oxygen.
- Compensate by installing a high flow air filter kit.
- Consider a fuel programmer to enhance ignition timing.
- Jet carburetor for added fuel at higher altitude if needed.
With consistent maintenance and the above performance upgrades as needed, your Rhino 660 can deliver max power for years to come.
Overheating Issues – Causes and How to Fix
Running too hot can quickly damage an UTV engine if left unchecked. Here are some common causes of Rhino 660 overheating and how to diagnose and remedy them:
Low Coolant – The #1 cause of overheating is simply having inadequate coolant in the radiator.
- Check coolant level daily before riding – should be at cold fill line.
- Top off and bleed air from the system if low.
- Pressure test system and fix leaks if losing fluid.
Faulty Water Pump – The water pump circulates coolant through the engine. A worn impeller can reduce flow.
- Inspect rubber impeller for missing or bent fins.
- Replace the pump assembly if impeller is compromised.
- Verify the pump seal isn’t leaking.
Thermostat – If the thermostat sticks closed it blocks flow to the radiator.
- Replace thermostat if old or questionable operation.
- Test in hot water off the machine to check it opens.
Radiator – Debris packed in the radiator restricts airflow. Scaled cooling channels reduce efficiency.
- Thoroughly clean the external radiator fins with compressed air.
- Flush debris from cooling channels.
- Use a de-scaling agent to dissolve mineral deposits.
Fan – Cooling fan not working? Check the fan relay, circuit, and blades. Replace as needed.
Lean condition – Running too lean causes hot exhaust.
- Check for air leaks causing an imbalanced fuel ratio.
- Clean carburetor jets and fuel filter if starving engine of fuel.
Monitor temperatures closely and avoid running if overheating. Left unchecked, it can warp cylinder heads and blow head gaskets. But with preventative maintenance and the above troubleshooting, you can keep your Rhino running nice and cool.
Troubleshooting Shifting Problems
The Yamaha Rhino uses a manual foot-shift transmission similar to a motorcycle. Common problems include slipping out of gear or difficult/incorrect shifting. Issues to look for:
Clutch – Worn clutch components cause slippage and shifting problems:
- Inspect the clutch basket teeth, plates, springs, pushrod, and bearings.
- Measure the clutch pack thickness – replace if below spec.
- Adjust clutch cable freeplay if engagement point is off.
Gear Damage – Bent shift forks, worn dogs, and grooved bearing surfaces can affect shifting.
- Check for any looseness in the shift linkage.
- Remove and inspect transmission gears periodically.
- Replace shift forks if bent or compromised.
Shift Lever – A loose shifter assembly reduces mechanical advantage.
- Tighten shifter mount bolts to the proper torque spec.
- Inspect shift lever-to-shift rod joints for excessive play and wear.
Detents – Worn shift detents allow the transmission to slip gears.
- Replace the shift cam and inspect detent springs if worn.
- Lubricate detent ramps and pins with moly grease.
Bearings – Worn mainshaft bearings inside the case can allow gear wobble.
- Listen for any growling noises during operation as an indicator.
- Plan for a transmission rebuild or replacement if bearings are shot.
With the right diagnosis and parts on hand, transmission repairs can be performed in a weekend. Just take time to methodically inspect components and address any underlying issues. Proper adjustment and lubrication will also help your Rhino shift smoothly.
Yamaha Rhino Engine Won’t Start Diagnosis
Nothing kills the fun faster than turning the key and getting no signs of life from your Rhino. Use this step-by-step approach to getting to the bottom of starting problems:
1. Battery and Electrical
Ensure battery voltage is over 12V when fully charged. Clean terminals and charge if under 12V. Verify battery cables and starter relay connections are tight. Bypass relay to test.
2. Fuel Delivery
Make sure fresh gas is reaching the carburetor. Check the fuel valves, petcock, filter, pump, and lines. Confirm no leaks or cracks. Verify carb bowl has fuel.
3. Air Intake
Inspect air filter and carburetor intake tract for restrictions or debris. Make sure airbox and carb boots seal tightly.
4. Ignition System
Spark is required for combustion. Remove and inspect spark plugs. Test for spark by grounding plugs while cranking engine. If no spark, check coil packs, plug wires, and CDI boxes for defects.
Need 100+ psi cranking pressure for combustion. Test compression on each cylinder to identify low or uneven pressure signaling piston ring issues.
6. Mechanical Issues
If tests above check out, suspect internal engine issues like stuck valves or timing chain problems. Time to dig deeper or head to the shop.
Methodically following these troubleshooting steps can quickly zero in on the root cause when your Rhino 660 won’t start. Fuel, air, and spark – focus on these essentials for combustion.
Keeping Your Rhino Running Strong
While the Yamaha Rhino 660 is generally a very reliable machine, it’s not immune to some common issues over time. But with routine maintenance and the troubleshooting tips outlined in this article, you can minimize downtime and keep your Rhino doing what it does best – exploring the trails with power and agility.
Monitoring fluid levels, inspecting filters and spark plugs, cleaning the carburetor and radiator, and testing for issues like compression loss and gear wear can optimize performance and longevity. And understanding the common problems these machines face makes it easier to diagnose issues when they do crop up.
With the right parts and tools on hand, you can handle many repairs right in your own garage or shop and avoid expensive dealer trips. If you rely on your Rhino for work or play, taking the time to learn proper operation, troubleshooting techniques, and preventative maintenance is essential knowledge.
So get out there and keep riding your Yamaha Rhino – we hope this overview gives you confidence to handle any problems yourself and keep your machine running strong for years to come!