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4/26/2022
Location
Delray Beach, FL
US
My 2009 KX450F will run fine for about 15 minutes before it shuts off. Once it shuts off I cannot start it back up immediately. I have to wait about 20 or so minutes (maybe to let it cool down?) to kick start it and it'll start right up. Along with this, I noticed when I rev the engine at a high RPM in neutral, the coolant overflow hose spews out coolant, or water... I'm not sure which.
I have read online that the cause could be many things, blown head gasket, bad radiator cap, or other things.... I recently had the head gasket replaced so I doubt it is that.
Will overheating cause the bike to turn off(stall) automatically? Any advice and information would be greatly appreciated.
I have read online that the cause could be many things, blown head gasket, bad radiator cap, or other things.... I recently had the head gasket replaced so I doubt it is that.
Will overheating cause the bike to turn off(stall) automatically? Any advice and information would be greatly appreciated.
What do you mean your not sure which? what ever you put in your radiator is what's coming out the overflow and unless you are running straight water then its coolant, why would you put straight water in the radiator unless your road racing or drag racing? You need to take it to a shop and let them handle it.
The Shop
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To those who gave me positive comments - thank you, I appreciate your advice.
There is no cracks in the cylinder head, the entire top end was just rebuilt by a professional shop. It cost me a ton of money, all gaskets were replaced, new spark plug was inserted, gaskets were sealed with proper sealant.. had an oil change, multiple times to assure oil was clean.
“He’s in way over his head” - thanks for your disrepesctful comment. As mentioned - I am just trying to understand. I suspect it could be 1. Faulty cap, 2. Warped head, 3. Radiator clogged, 4. Thermostat malfunction, 5. Faulty water pump. - This is just what I’ve obtained from a Professional service shop that did not see the bike in person and gave me advice over the phone.
I'd start there first.
Again, Id start with your gas cap first before the big stuff.
Pit Row
The pump transfers the coolant from the radiator, through the radiator hoses, into your engine where it cools the engine but is made warmer from the heat transfer during this process. That coolant is then pushed back to the radiators to be cooled while the coolant that was just cooled in the radiators heads towards the engine. Repeating the process in a constant flow.
The easiest check here would be to swap your radiator cap with someone else's and see if it that process continues. When you state you're holding it at a consistent RPM, how long are we talking? If the bike is hot enough, it'll push coolant out no matter what as the stock 1.1 radiator caps aren't typically efficient for most track riding.
Back in 2009, many OEMs, Kawi included...were having fuel pump issues that would appear with heat and run time. Your fuel pump could be an issue. A bad stator could possibly be causing the problem as well.
Do you know what brand of parts the shop or mechanic used when rebuilding the engine and how long ago did the work happen? If you just got the bike back and it's having these issues, I would return to who did the work or find another reputable source to assist you. If your experience is as lacking as it seems, you could really chase your tail on this one and either cost you more money just trying things or worse, cost you a bundle more if there's a serious problem and the bike receives further damage.
If the head is warped, nothing is going to help you until it's fixed/replaced...
My theory on the stalling and not starting for my YZ450, was the coolant was slowly leaking out while running, making the engine hotter. The coolant temp sensor would try to compensate for the higher engine temps and lean the bike out to a point where there wasn't enough fuel to run. Shut down for 20 min and it would cool off and start right back up.
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