2013 Yamaha YZ85 Smokes on Startup – Causes and Fixes

Shop parts for a 2013 Yamaha YZ85 Dirt Bike.

Understanding Startup Smoke on the 2013 Yamaha YZ85

Seeing smoke from your 2013 Yamaha YZ85 when you first fire it up can be concerning, but it isn’t always a sign of trouble. Knowing when smoke is normal and when it signals a problem is key to keeping your YZ85 running strong. This guide breaks down the most common causes of startup smoke and how to address them, so you can get back to riding with confidence.

When Is Smoke on Startup Normal?

  • Cold Starts: A brief puff of smoke is common when starting the YZ85 after it’s been sitting, especially in cooler weather. This is often due to condensation or a small amount of excess oil burning off in the exhaust.
  • After Long Periods of Inactivity: If your YZ85 hasn’t been started in a while, oil can settle in the crankcase or exhaust, leading to a smoky startup. This usually clears up quickly as the engine warms.

Common Causes of Excessive Smoke on the 2013 Yamaha YZ85

If the smoke is thick, persistent, or has a blue tint, it may indicate an underlying issue. Here are the most likely causes specific to the 2013 Yamaha YZ85:

  • Premix Ratio Issues: The YZ85 relies on a precise fuel-to-oil premix. Too much oil in the mix can cause heavy smoke at startup and during riding. Double-check your premix ratio and ensure you’re using the correct measurement for your riding conditions.
  • Oil Pooling in the Crankcase: If the bike has been stored for a while, oil can settle in the bottom end or exhaust. This pooled oil burns off when you start the engine, creating noticeable smoke. Regularly starting the bike and running it for a few minutes can help prevent this.
  • Worn or Leaking Crank Seals: The crank seals on the YZ85 keep transmission oil and air separated from the combustion chamber. If these seals wear out or fail, transmission oil can seep into the crankcase and burn, causing persistent blue or white smoke. This issue typically requires seal replacement.
  • Excessive Idling or Rich Jetting: Running the engine too rich (too much fuel or oil) or letting it idle for extended periods can cause unburned oil to accumulate in the exhaust, leading to smoke on startup. Adjusting the carburetor jetting and avoiding long idle times can help.

Diagnosing the Source of Smoke

To pinpoint the cause of smoke on your 2013 Yamaha YZ85, consider the following steps:

  • Observe the Color and Duration: Brief, light smoke that disappears as the engine warms is usually harmless. Thick, blue, or white smoke that lingers may indicate oil burning.
  • Check the Premix: Review your fuel-to-oil ratio. For the YZ85, a common ratio is 32:1 or 40:1, depending on riding style and oil type. Too much oil will increase smoke.
  • Inspect for Oil Leaks: Look for oil residue around the crankcase, exhaust, and cylinder base. Leaks can point to worn seals or gaskets.
  • Monitor Oil Consumption: If you notice the transmission oil level dropping without external leaks, it may be entering the combustion chamber via faulty crank seals.

Practical Fixes for Startup Smoke

  • Adjust the Premix Ratio: If you’ve been running a rich oil mix, switch to the recommended ratio for your YZ85. Use a quality two-stroke oil and measure carefully.
  • Run the Engine Regularly: Starting and running the bike periodically helps prevent oil from pooling in the crankcase and exhaust.
  • Replace Worn Crank Seals: If you suspect crank seal failure, replacing them is the only long-term fix. This job requires splitting the cases and is best done with the right tools and patience.
  • Clean the Exhaust: Excess oil can build up in the silencer and expansion chamber. Removing and cleaning these components can reduce smoke and improve performance.
  • Check Carburetor Settings: Ensure your carburetor is jetted correctly for your altitude and riding conditions. A rich mixture can contribute to excess smoke.

When to Take Action

If your 2013 Yamaha YZ85 only smokes briefly on cold starts and clears up quickly, it’s likely normal. However, if you notice any of the following, further inspection is warranted:

  • Persistent, thick smoke that doesn’t clear after warm-up
  • Noticeable drop in transmission oil level
  • Oily residue around the exhaust or crankcase
  • Loss of power or rough running

Addressing these issues promptly will help maintain your YZ85’s performance and longevity.

Keep Your 2013 Yamaha YZ85 Running Clean

Startup smoke on the 2013 Yamaha YZ85 is often a normal part of two-stroke ownership, especially after periods of inactivity or cold weather. By understanding the common causes and knowing when to take action, you can keep your bike running clean and strong. Regular maintenance, correct premix ratios, and attention to engine health will ensure your YZ85 delivers reliable performance every ride.

Related Shopping Categories

Shop Oil for a 2013 Yamaha YZ85 Dirt Bike.

Shop Spark Plugs for a 2013 Yamaha YZ85 Dirt Bike.

Shop Carburetor Accessories for a 2013 Yamaha YZ85 Dirt Bike.

Shop Gaskets for a 2013 Yamaha YZ85 Dirt Bike.

Shop Air Filters for a 2013 Yamaha YZ85 Dirt Bike.

Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.