How To Fix Hard Starting Your ATV When Warm

Sometimes an ATV will start fine the first time, but if you turn it off and try to start it again during your ride, you’ll struggle to get it working again. Most of the time, we think of ATVs struggling to start all the time or when they’re cold. If this odd situation is happening to you, read this post to learn how to fix hard starting ATVs when they’re warm.

atv riding gear in summer

Why ATVs Have a Hard Start When Warm

There could be many reasons for this particular issue.

Air Filter

You should check your air filter first because it’s the easiest thing to check and fix. If your air filter is dirty or the intake is clogged, it won’t allow enough air in for your quad to consistently work as it should. Overoiled filters can also cause issues because the oil changes when it gets warm.

You can visibly check your air filter for signs of an issue. If it’s dirty or clogged, you can just change or clean it.

If you need to determine if you over-oiled your filter, you can take it out and try to start your ATV. It should fix the issue. This is just a diagnostic test, though. You can’t ride without an air filter.


You may need an oil change. Sometimes when oil is old or dirty, it can cause an engine to not want to start when it’s warm.

Spark Plugs

First, look at the spark plugs. You can often tell if something is wrong with them because they are wet, white and crusty, or soot-covered. Depending on how bad the damage was, they might be able to be cleaned and used again.

You can determine if your spark plugs have a spark by taking them out of the engine, plugging one end into the spark plug wire and holding the other to a grounding part of the engine. Try to start the engine and see if any sparks fly.

Don’t automatically assume your spark plugs are bad if they receive no spark but they look fine. Rule out some other issues first.

The coil can be to be blame for hard starts, if you didn’t pass the spark plug test. Test your ignition coil with a multimeter.

You should also check the electrical connections all over your machine; the battery cables, your CDI box, the solenoid, everywhere.

Make sure your idle mixture is correct. If it’s too rich when you’re idling, it can cause hard starts when your engine is warm.


Compression is probably not to blame if you’re experiencing ATV hard starting when it’s warm, but you could check it just to be sure.

You can do a compression test. If you’d like a quicker test before you can get to that, try to start your engine with the recoil instead of the electric starter. If the problem suddenly seems fixed, this will indicate a compression problem.


Check your valve lash and your intake and exhaust valves. Testing them is pretty easy for a DIYer. You just need your service manual. Fixing them could be more of a job for a mechanic.

Fuel System

You could have an obstruction in your fuel system. This is particularly likely if you let your ATV run low or out of gas as it will have pushed gunk through your system where it may have gotten lodged.

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