Smoke or steam coming out bottom of bike

Rode my Yamaha wr450f around for probably 45minutes, stopped to send a text and noticed it was smoking out of a tube or tubes on the bottom. Have no idea why this happened. Attached a video of it to hopefully get answers. The coolant was completely drained out after this also

you boiled off your radiator fluid.

this happens when you start a ride with too little fluid, or when slowly climbing hills too much without giving the engine a chance to cool down.

It also happens when stupid people only use water to fill their radiators. Usually a 50/50 mix of radiator coolant and distilled water is used.

If you fill it to the top with 50/50 and keep a good pace riding the trails and it happens again then the head gasket is blown. Don't ride far from home when testing it in case you have to push it home from losing all fluid which can lead to engine seizure.

Thanks. Haven't run it since yet so hopefully the head gasket is good. Noticed the coolant level was higher before I rode it that day and a coolant bottle empty laying in the ground, someone doesn't want me riding lol


Filled the coolant tank up, 50/50, let the bike run for about 15mins or so, rode it around the block, had noticeably less power. Pulled into my garage, it made a noise and all the coolant drained out.

No smoke this time, but afterwards the coolant tank was filled with a black liquid, doesn't smell like oil or anything

Have you put coolant in the actual radiator ??


The tank is for fluid expansion only.

Oh, did not know that. I've only been putting it in the rear tank near the muffler that's labeled coolant. I opened the cap on the radiator and it had a liquid filled up to the top already

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