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How To Break in a Rebuilt Snowmobile Engine?

How To Break in a Rebuilt Snowmobile Engine?

Breaking in a rebuilt snowmobile engine ensures that it performs efficiently for a longer time by allowing all piston rings, nuts, and connecting rods to sit in properly. But you have to do it right to avoid damaging the engine.

Here’s how you can break in a rebuilt snowmobile engine in 6 simple steps:

  1. Premix oil for the snowmobile without an injector oil pump.
  2. Warm up the engine.
  3. Ride the sled under 6000 RPM from 0- 100 miles (0-160km).
  4. Stop and check the snowmobile.
  5. Ride under 8000 RPM from 100-300 miles (160-500km).
  6. Ride normally 300 miles (500km).

Read on for a more detailed guide on how to break in your rebuilt snowmobile engine while taking the necessary precautions for a safe and enjoyable ride.

1. Premix Oil for the Snowmobile Without an Injector Oil Pump

Mix the right oil with the fuel at the recommended ratio from the skimobile manufacturer. You can find the appropriate oil and ratio in the operator’s manual. 

It’s advisable to mix only fresh and approved oil. Otherwise, your engine and fuel system may experience blockages and reduced flow rates due to improper, incompatible, or inadequate fuel (source).

Here’s how to premix oil for the snowmobile without an injector oil pump:

  1. Turn off the engine slowly to let air escape from the tank. This will also stop the fuel from flowing back.
  2. Fill the tank with the premix. This should be done in a warm area to avoid overflow, as increasing temperatures can cause the fuel to expand. 

If your sled has an electric oil pump, you won’t need a premix fill. However, the fuel injectors and engine oil pump will require breaking in along with the engine. Breaking in the engine oil pump will further enrich the supply of oil to the engine. 

If you feel your fuel filter needs to be replaced, I recommend the HURI 3pcs 3/16″ 1/4″ Inline Gas Fuel Filter from (assuming it’s compatible with your model). The package includes three pieces, and if you’re not afraid to do a little DIY, it should be easy to install.

2. Warm Up the Engine

To warm up your snowmobile’s engine, follow these steps:

  1. Start the snowmobile and hold the oil pump cable wide open for 1-2 minutes. 

Let it sit for 3-5 minutes in warm weather before allowing it to cool.

  1. Check the sled for any leaks, and if any, fix the seals. 
  2. Repeat the heat cycle one more time to get properly warmed up. 

Heating and cooling will prevent the engine from overheating. However, you should warm it for about 5-10 minutes under cold weather conditions.

If you have a newer sled model, its coolant temperature warning icon will go off when the engine reaches the proper operating temperature. For snowmobiles without the gauge, you can tell the engine has warmed up when the heat exchanger is warm.

Warming up the engine before you ride can prevent the engine from getting damaged, as cold starting can cause tremors that force the cylinder to scratch the piston and lower the engine’s lifetime.

3. Ride the Sled Under 6000 RPM From 0 – 100 Miles (0–160km)

Remove the brake and apply the throttle to engage the drive pulley. Ensure that you drive slowly for the first 2-3 minutes before gradually increasing the speed to 6000 RPM in a snow-packed field or lake. You should vary the speed between 6000 RPM and below to minimize friction on the rings so they can sit properly on the cylinder wall without any damage. Doing this also prevents the engine from overheating.

You can ride slightly above 6000 RPM, but only for short periods.

Besides, fuel injectors will also get broken in as they require the engine to run for 2 hours at above 3,500 RPM.

4. Stop and Check the Snowmobile

Inspect the sled to see if there are any fuel or oil leaks so you can tighten the rings and nuts. Top up the fuel, oil, and water if necessary for the efficient functioning of the vehicle.

You should also check the lines and spark plugs to ensure they’re still in good condition.

When dust builds up on the piston head and wears it out, the spark plugs may fail to ignite the engine properly, and you may end up with a sluggish engine. So you should clean up the dirt or even change the plugs if you notice that they’re worn out.   

5. Ride Under 8000 RPM From 100–300 Miles (160 – 500km)

Restart the tracked vehicle and up the speed to 8000 RPM while constantly varying the throttle between wide open and slightly open. You can also go above that speed, but not for too long. Also, keep monitoring the temperature to avoid excessive heat buildup by lowering the speed when you notice the engine getting warm. 

During this time, the engine oil pump’s enrichment will take 10 hours for it to get broken in at speeds above 3,500 RPM. That’s the same amount of time the rebuilt engine can take to get load and seat in.

After finishing the 300 miles, the engine will be broken into, and it’ll achieve full power. With that, you can be assured that it’ll operate efficiently for far longer than if you didn’t break it in.

6. Ride Normally After 300 Miles (500km)

Having done the above, your engine should be ready for crunch time. At this stage, you can crank up the engine and ride the snowmobile like how you normally would. Remember that, after the sled reaches 500 miles (800 km) of operation, you should change the oil and replace the filter. This will prevent any dangerous metals from entering the engine through the oil and damaging it.

Final Thoughts

Breaking in the rebuilt engine of your snowmobile is simple as long as you follow the tips above. Always remember to follow your owner’s manual guide on how to break in a rebuilt snowmobile engine since different models require different break-in methods. If you don’t have your manual (or lost your copy of it), you can always search for the proper break-in method from reliable online sources. 

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