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Sunk EXC 500 Starting and idling issues

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I posted this content in the KTM 4 stroke section but hopefully will get more eyes on it here. I will add I am considering buying the bestdualsports TPS tuner and exhaust cap to my things to try as the emissions canisters are removed. Not sure that'll help but it seems like the throttle position is a key factor here...

"Reviving my sunk EXC500

I recently sunk my 2015 exc500 in a dirty mud hole. I was thrown off and the bike drank till it was full. I removed the spark plug and ejected as water with kickstarter then electric starter. It took a all the battery power and jump starting to get it going. The only way it would start way to hold throttle open and work the starter hard. I limped it for a few miles through the trails back to camp but it died on a steep uphill. I have now flushed 5 oil changes and to get milk and silt out. I cleaned all the fine silty dirt out off the air box and line. Changed the fuel and fuel filter. The bike is still really hard to start, only gets going with throttle cracked a bit and does not like to idle. I now took all the emissions canisters off (one was soaked for sure) and plugged holes with xcw plug and cap from local shop. The bike will still only start with throttle cracked a bit and holding on the starter for a long period. After warming up it'll idle but is finicky. The water my bike drank was very muddy. I really hope I didn't do too much damage. Any tips that'll help me get the bike running and limit further damage? "

 

https://thumpertalk.com/index.php?/topic/1238241-Reviving-my-sunk-EXC500-/page__view__findpost__p__13868122

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Pull the injector nozzle and pressure clean it.  It will be thrashed.

Inspect the pump for dirt damage (needs to run 50psi for 5+ minutes)

If the TPS was submerged, it's probably toast....but it will give you a FI error if it's bad (2016 and later), otherwise it may put the ECU into 'safe' mode, which prevent you from getting full power.

I would bet the injector is corroded and filthy.

 

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Pull the injector nozzle and pressure clean it.  It will be thrashed.
Inspect the pump for dirt damage (needs to run 50psi for 5+ minutes)
If the TPS was submerged, it's probably toast....but it will give you a FI error if it's bad (2016 and later), otherwise it may put the ECU into 'safe' mode, which prevent you from getting full power.
I would bet the injector is corroded and filthy.
 

Thanks for the tip! I'll be doing this on the upcoming weekend. Fingers crossed!

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Leak down test. The last 500 I seen this happen to destroyed the rings and cylinder wall

Thanks for the info! I'll see what my local shop can do for me.

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Silt in the combustion chamber can also damage the valves and valve seats, which would lower compression and induce hard starting when cold.  

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