04 TC450 dies in water

The first time I forged a relatively small stream on my 04 450 it came to an abrupt stop. The starter would crank over but absolutely no indication of a spark. Once it was dragged out it fired right up. I didn't take this very well. The water was only up to the shifter when I came to a complete stop in the middle of the stream.

Is this an electrical feature of the bike or could it be a carburetor overflow hose issue?


I would think that if you had the engine cradle submerged for a while while the bike is running it would suck water up the vent tubes into the carb. It might take 15 to 20 seconds or more to do though. the intake vents should be run into the airbox to alleviate any dust pick up. I was picking up dust in my intakes and into the float bowl. I ran the into the airbox and it stopped. Some guys put little air filters on them.

The stream was only 15 - 20 feet wide so I wasn't in long. It's funny that it fired up immediately when I got it out. I almost ran the battery dead trying to start it in the water. I was planning to run the hoses into the air box but haven't yet. I guess I'll give it a try and see if it happens again. I'm guessing that there shouldn't be an electrical issue that would cause this. Now that were headed into the cold of the winter, I'll hope to heck that it doesn't happen again.

Thanks for your reply!

Had a similar thing happen a couple of weeks ago,was in the water 20 or 30 seconds and it coughed and nearly died,my take is its like the potato in the exhaust only with the carb,I ran the hoses up under the tank,not the float bowl one,its the overflow.

The carb is under a vacuum so if all the hoses are submerged it will suck water. If you take the two side hoses that are going up and route that into the airbox area and leave the other 3 hoses going down you should be fine.

One time to prove the theory we took a stock MX bike into a mud puddle and watched the brown water get sucked up the hoses. With this simple mod you should be fine in the water.




You can kind of see the hoses routed in the pic.


And when you over do it and a freek set of waves come in...... Nothing like sand and pacific ocean in the engine... I really thought this was the end of the "champions bike".



With the Mikuni on my '04, on both sides of the carb there is a "T" coming out of the carb . The tubes going up out of the T are the intake sid or breather tubes, these are the ones that go into the airbox. The tubes that run down out of the T is what I call the exhaust side or the bleeder tubes. I tried running the exhaust tubes into the air box and the bike ran like shit. I could see fuel trapped in the low spot created by routing the tubes into the airbox. I pulled these two tubes out of the air box and let them run down & out the normal way and the bike ran great.

What is happening here is the air area above the gas level in the bowl must be vented to atmosphere or gas can not run into the bowl. The manufactorors run all those hose down and long as this is the best way to reduce the risk of fire from gas getting on exhaust when bikes are on their side etc. When we ride into water even not up to the frame, those hoses hang in water, gas can not flow in, engine dies. Last year I stopped in a stream of about 8", left the engine idling in neutral while I rinsed some mud off a glove, engine died, it took 3 of us to push the bike up a steep bank , then the engine started. In hind site I should have pulled one hose up and waited 5 seconds.

Ever since then I have one hose down, the other up and extended back down to the bottom of the air box. On my 05 Kehein I toss the "T"s and nuke 2 hoses (and the closing cable of the throttle)


That's a good idea and it works real nice too.


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