05 450 EXC Hot Gas?

OK...riding tight trails this weekend, about 75 degrees ambient temp. The bike dies while hitting the throttle in an uphill corner. After I pull it back onto the trail, I hit the button and the battery is dead, so I begin kick starting it. It would not start after several kicks. Thought maybe it had overheated, so as a last resort I drained the carb bowl and it started first kick. This happened several times throughout the weekend. Bike dies (or I just shut it off), starter won't turn over, won't kick start until I drain the carb bowl, then kicks right over. Got back to camp, and checked/cleaned the battery connections. They looked pretty corroded. After cleaning, the starter worked fine. But why would I have to drain the carb bowl to get it to kick start? Thanks for any help.

Make sure you have removed the check valve in the gas cap and don't put one of the little check valves on the vent hose coming out of the gas cap. It must vent freely in both directions. What can happen is the gas tank can build pressure and sink the float and flood it. Very common problem.

Another thing to check is that the vent hose coming out of the carb. are clean and not clogged. You also need to re-route two of the vent hoses to the air box so the engine won't die when doing water crossings.

It has the little check/PCV type valve on the gas tank cap. Should I remove this check valve? If so, do you just leave the tube open, or should I replace it with a new one? Thanks for your help.


The tank MUST vent freely in both directions.

Great. I'll pull the check valve out. Thanks for your help.

Try some 'water wetter' additive. It works with AF, distilled water or coolant. My 450 did much better in hot weather removing & replacing it with one ounce of WW. Kind of a fan in a bottle mod.

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