In the midst of battle or just bar-banging fun on the trails you can easily miss or even ignore the mounting symptoms that indicate an overheated engine on your dirt bike or ATV.
If you adhere by the adage that there's no quitting in riding or racing as steam spews out the radiator, choose so at your engine's peril, though who actually pulls off when the finish line lingers a minute plus 2 away. Keep in mind that an overheated engine ridden for too long causes damage to internal engine parts as well as to the cooling system. Catch it early and get it cooled off you probably won't have much further issue but let the radiator fluid boil over and/or completely evaporate you might have a complete engine rebuild and radiator replacement in your very near future.
Engine overheating occurs for a number of reasons including a leaky or damaged radiator and a bad water pump but other causes not even precise routine maintenance can prevent raises the temperature. A clogged radiator from mud and debris or even riding on a hot day can overwhelm the cooling system no matter how new and high quality the coolant. The best line of defense always consists of fresh coolant, enough coolant (riding with low coolant almost guarantees an overheated engine) and a high quality coolant made specifically for dirt bikes or the powersports industry from a trusted manufacturer.
See the white plume? This MotoSport employee took a risk and finished a Loretta Lynn's battle on an overheated bike
When a dirt bike or ATV engine begins to overheat a number of warning signs present and if you pay attention especially when riding in demanding conditions like the heat or mud you can at least determine whether to risk continuing your ride. The following conditions result from an engine overheating:
- Power loss
- Dripping fluid
- Super hot case
- Ticking noise in engine (oil burning off)
- Sweet smell (burning coolant)
- Piston expands and seizes (you waited too long)
None of these occur all at once and the symptoms generally follow a specific order. You probably smell the burning coolant around or at the same time steam bellows out from radiator. If riding, don't expect to notice the fluid dripping but most certainly you can feel the hot case. Depending on conditions and how hard you ride, you might have five minutes or even an hour but consider your time up in about 15 minutes if you plan to gut it out.
Once you feel the bike losing power you need to shut it down. Before long, if not already, you will hear ticking noises in the engine because oil has slowly burned off at this point and engine parts no longer have enough lubrication to function properly. Shortly after the ticking noises the piston will seize.
If you catch the overheat early and turn off the engine (the only solution to an overheated bike) check the radiator fins for clogs or bending, check to see if the water pumps spins freely and if all checks out OK, dump the old coolant as it probably lost most, if not all, the protective properties and add fresh coolant. Replace the radiator if you find bent fins or other damage.
Unfortunately, waiting too long, even if you shut down after losing power or hearing the clicking sound and before the piston seized, requires a rebuild. You will need a new head and base gasket anyway after letting the engine get that hot so definitely replace the top end and inspect the bottom end for any damage.