Swamped WR450

About 3 weeks ago, my cousin found a really deep mud hole, and sunk his '04 WR450 in the mud. It was buried up to mid gas tank and took almost 3 hours to get out. I really wish I was there to see that, but then again, I probably would have been the first to go through the drainage tube instead of him.

He got it home, and we tore it apart. We found mud throughout the carb, and in the head. We disassembled the whole top end of the engine, washed all the parts in a parts washer, and re-assembled.

We triple checked the valve clearance, cleaned out the carb 3 times, and we are still getting a lean fire. The plug is turning white, the backfire popping is unbelievably loud, but the bike has plenty of power otherwise.

My cousin is flipping out, saying he's just going to get a new bike... I'm thinking that we are really close to having it run again. Is there anything else anyone can think of that maybe we didn't think of? I hate to see my cousin blow 7500 bucks on a new bike, especially since this one isn't really in the best shape to sell. Any ideas would be appreciated.

Here's all the things we did to the engine:

The bike was never started or tuned over after it sank. We got as much mud out as we could before finding TDC. We removed the airbox, carb, head, and cylinder wall. All the valves & springs were removed from the head, cleaned individually, and installed in the same position they came from. Proper lapping paste was used & new seals were installed. The cylinder did not have any scoring, so we lightly re-crosshatched the wall, and re-ringed the piston. There was no visible dirt or mud below the rings.

The carb was soaked in cleaner, and we shot carb cleaner and air through each passageway. Where we could, we used pipe cleaners to clean out passageways.

The spark arrestor of the exhaust was totally clogged with mud. But, the water that was inside the pipe was really clear and clean. We made sure everything was cleaned out.

You know, thinking about what to write made me think of the electronic timing. I really hope he did mess up his CDI, but with the current symptoms, we really need to check the timing advancement. I love when forums help that easily...

It's got to be in the carb, and it sounds like the cam timing is off.

I agree that makes sense. I was there when we installed the cams, I know that both had their marks in the correct locations. Before we put the cover on, we turned the motor over once, and the marks all lined up again.

I personally think there is still crap in the carb, but my cousin is adimate that it's totally cleaned out. Other than that, or a timing advancement issue, I'm out of ideas?

Which mark did you line up with, the H or the I?

I would not trust any carb cleaned unless it was done with compressed air and lots and lots of brake cleaner. Don't use Carb Cleaner! It will mess with the rubber in the Float valve, the Vacuum plate on the slide, the Fuel screw o-ring, etc. You have to take out the pilot jet and hold it up to the sun to make sure all the passages are clear.

I've cleaned a pilot passage with brake cleaner and it came out clean. Added some compressed air, and sand came out!

You need a manual, then re check the cam timing(s)

Proper lapping paste was used & new seals were installed.

Not to be a downer, but lapping Ti valves is a no-no. You may have inadvertently removed the hard coating from the sealing surfaces of the valves.

no kidding, with most of these modern fourstrokes you should NOT be lapping valves. Is that true of honing or re-crosshatching as well? I think there's a coating on the inside of the cylinder wall too. did you guys use a manual?

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