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Sand killed my kx450f

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My Ride: 2009 KX450F

Ok, took a trip to Silver Lake dunes in MI. Ran into some engine problems.

Background: I had been trail riding this bike for a bunch of rides leading up to this day with no performance issues. New to me bike this April, sat for months, didn't actually start riding it until a few weeks ago really. I have never washed the air filter. It was oiled and washed by the previous owner though and he took care of it pretty meticulously and knew bikes. Leading up to my dune ride, even with a bunch of trail riding, still didn't wash the air filter (and still no engine problems). 

Dune ride Day 1: rolled in, in the afternoon, but didn't have time to put on filter skins I had. Rode for about 2 hours, no problems. 

Dune ride Day 2: late start, but did some prep in the lot before riding. Don't know if any of this matters, but the only notable thing I did with air filter was put a FRESHLY OILED AND WET skin over my air filter. I know, it should've been dry, but I didn't prep the night before, but didn't want to ride all day with no skin. I think it being wet/oiled actually attracted more sand. Perhaps a better alternative for sand riding is a DRY air filter and a DRY filter skin. Still protection, but sand won't stick to it. I don't really get why air filters are oiled anyways. I get that the idea is to make stuff harder to pass thru filter and make it stick, but it seems like a catch 22 cuz it will cause it to get dirtier cuz it's attracting dirt. Sort of like a lubed up chain will attract dirt and grime on it. Anyways, didn't really have any notable spills/wrecks (had some easy drops), so perhaps that's how sand entered airbox, but anyways. The bike worked great for the first few hours. Then, out of nowhere, it started to get boggy, or feel like it was bogging. It's FI, so it shouldn't be bogging, but that's the best way to describe it. The bike wasn't giving me any power. I figured (hoped) it was low on gas, so I parked it for a while, walked down grabbed my gas and fueled up. This was a windy day, so perhaps sand accumulated a bit while riding and then while sitting there waiting for gas. Gassed up, but the engine only got worse. Got so bad, I could barely go across flat ground in 1st gear (grades I coulda lugged EASILY in 4th gear and powered around). I mean, I was wide open in 4th/5th tearing around. I rode back down and cut it off. Haven't touched it since. 

I'm not sure where to start or how to troubleshoot on this one. I've never gotten into the airbox/FI system. I'm not sure what happened to the engine (sand in cylinder maybe, scratched walls, rings lost seal, maybe it's just a dirty air filter, but considering it's been ridden dirty without cleaning whatsoever, shouldn't be that). When I opened airbox last night to check for sand, there was some gunk around the edges, but to me it didn't seem like anything that woulda killed my engine like it did. The air filter was still relatively clean. Even the skin over the filter was relatively clean. 

Any idea what's wrong? What should I check? I'm afraid to start it and let it exacerbate problems. 

Edited by Kwest364

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Do a leak down test. Check valve clearances. Wort case is the barrel, piston, head and crank are trashed. Only until you test and inspect can you know the extent of the damage. Filters should be cleaned at least every ten hours of run time and certainly the same day you buy a bike, new or used. Sorry for your misfortune.

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2 minutes ago, Kwest364 said:

2009 (I just edited in original post)

thanks.

 

You need to do some investigative work on your end before we can be of any help.

check fuel filter, check for sand in your fuel pump filter, check of the filter was actually sealing on the air box....list goes on and on.

I ride at silver lake, i get sand in my air box. Not from crashing but cause the paddle tire is a beast. Besides riding the bike harder cause its in the sand. ive never had a issue. I change filters every ride no matter what or how much i ride that day. 

 

good luck!

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Air filter must be serviced on an appropriate schedule for the conditions you ride in.  One day at the dunes is enough to do it.  Back east where the dirt stays on the ground and you don't have dust, you could probably go for months.  If you go too long, the filter will dry up and sand will fly right through it.  Foam filters without oil aren't worth a shit other than keeping birds and large rocks out of your engine.  The only media that works dry is paper but it clogs far too quickly for dirt bike usage.

For me, I ride dry conditions from hard pack to moon sand.  I can go four or five rides.  If I'm riding with buddies that can be cut in half.

Filter skins are a half assed way to cut down on filter cleaning.  I would skip them.  There is no substitute for a half inch of properly oiled two stage filter media.  I fear you are in for a very expensive repair here.  The very first thing to do when you buy a new bike is clean the air filter.  This is part of the process of inspecting and going over a new bike.

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The purpose of the filter oil is to attract dirt so it doesn’t get sucked into your EFI/carb system and through valves and into motor. As already mentioned a dry foam filter ain’t worth shit. If I’m riding trails, especially with buddies, I thoroughly clean and oil mine every 3 or 4 rides at most. Keeping a clean and oiled air filter is one of the easiest ways to keep your bike running right and healthy.

As far as what damage has been done, it’s hard to tell at this point without looking further into it. I’d start by cleaning your air filter and PROPERLY oiling it. Watch a video on how to do this. Your old one might just be so full of sand and then a skin on top that’s also plugged up might just be suffocating the bike best case scenario. At worst, sand made it through, and trashed your valves, top end, and bearings. Next I’d check your fuel filter see if that’s gummed up. After that move to valves. Basically go from least complex to most complex/time intensive

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1 hour ago, Fore-50 said:

thanks.

 

You need to do some investigative work on your end before we can be of any help.

check fuel filter, check for sand in your fuel pump filter, check of the filter was actually sealing on the air box....list goes on and on.

I ride at silver lake, i get sand in my air box. Not from crashing but cause the paddle tire is a beast. Besides riding the bike harder cause its in the sand. ive never had a issue. I change filters every ride no matter what or how much i ride that day. 

 

good luck!

Yeah, I know, I'm trying to investigate, just wasn't sure how to go about investigating. Which is the point of my post. Anything else I should check? After fuel filter, fuel pump filter, filter sealing on air box, what else? More of those ideas, that's perfect. 

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I should let everyone know, I've only put 10 hrs on the bike since I've had it, so I've not ridden it that much. Just so everyone doesn't think I've put 50 hrs on and haven't done ANY maintenance. 

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