Mud sucked into engine - WR250F

[TY REX]

A worst-case scenario happened yesterday: my bike fell over into a 2-foot deep mud bog while running. Mud got sucked up into the engine and everything. The bike hydro-locked and I pushed it back to camp. 

We drained the oil and it looked just like the mud that got sucked in. Removed the spark plug and cranked and blew out the mud. Cleaned the oil filter and air filter. Drained the float bowl. 

We got the bike back running. But now there's blue smoke coming from the muffler like a two-stroke, so the piston and rings will have to be replaced.

I'm starting this thread to chronicle the overhaul and for anyone to chime in with advice.

[JonWR250f]

Should be an interesting read, I’ll keep an eye on this one

[intimdatr]

Feel free to check out Jon's and mines posts, plenty of pictures to make the task far less daunting. 

[Vintage Not Pimpage]

Strip and clean the whole thing asap and you might just get away with only a piston kit.

[Torchsport]

Might be some helpful info here. 

 

 

Edited June 12, 2018 by Torchsport

[ehall]

wonder if you could of saved the top end by not turning it over before taking it apart?

[intimdatr]

1 minute ago, ehall said:

wonder if you could of saved the top end by not turning it over before taking it apart?

Hindsight is always 20/20. 

[ehall]

1 minute ago, intimdatr said:

Hindsight is always 20/20. 

absolutely

[ThrustWasher]

On ‎6‎/‎10‎/‎2018 at 11:20 AM, TY REX said:

A worst-case scenario happened yesterday: my bike fell over into a 2-foot deep mud bog while running. Mud got sucked up into the engine and everything. The bike hydro-locked and I pushed it back to camp. 

We drained the oil and it looked just like the mud that got sucked in. Removed the spark plug and cranked and blew out the mud. Cleaned the oil filter and air filter. Drained the float bowl. 

We got the bike back running. But now there's blue smoke coming from the muffler like a two-stroke, so the piston and rings will have to be replaced.

I'm starting this thread to chronicle the overhaul and for anyone to chime in with advice.

Omg why would you start the bike after its blowing mud out of the spark plug hole?????? For future reference when going through deep mud holes always keep your thumb by the kill switch!

Edited June 12, 2018 by ThrustWasher

[TY REX]

The answer to that question is simple: I didn't know better and I wasn't taught that in public school. It doesn't make sense to ask someone why they did something when it is an admitted mistake.

Anyway, the second oil change on the bike showed a dark, battleship grey color. Any suggestion on what caused this, i.e., was it mud, steel, or both?

Shortly after starting (when the engine warmed up) copious amounts of white smoke came steady from the muffler. I'm guessing that this is the piston rings?

I maybe could have saved the top end by not turning it over; so let that be a lesson for anyone else. Needless to say, damage done.

I'm going to overhaul the top end and then take the sides of the case off and clean. Any tips?

I'm also going to clean out and rebuild the carburetor. 

 

[ThrustWasher]

30 minutes ago, TY REX said:

The answer to that question is simple: I didn't know better and I wasn't taught that in public school. It doesn't make sense to ask someone why they did something when it is an admitted mistake.

Anyway, the second oil change on the bike showed a dark, battleship grey color. Any suggestion on what caused this, i.e., was it mud, steel, or both?

Shortly after starting (when the engine warmed up) copious amounts of white smoke came steady from the muffler. I'm guessing that this is the piston rings?

I maybe could have saved the top end by not turning it over; so let that be a lesson for anyone else. Needless to say, damage done.

I'm going to overhaul the top end and then take the sides of the case off and clean. Any tips?

I'm also going to clean out and rebuild the carburetor. 

 

You're going to need to split the cases and take the entire motor apart. If its in the cylinder and oil its in the crank and tranny!

[Vintage Not Pimpage]

Just split the cases and clean everything out asap or you will need to replace all bearings/crank etc 

[TY REX]

So, along with the piston rings likely being trashed, the starter system busted too. When I hit the start button, the electric motor just spins freely. Upon further investigation, I found that the starter clutch drive gear spins freely---is it supposed too? Is this the problem? If so, anyone ever take a flywheel off a WR250F?

 

 

[JonWR250f]

I think off the top of my head it spins one way and locks the other, on a one way bearing. 

Youll need a flywheel puller, 30mm

Edited June 16, 2018 by JonWR250f

[JonWR250f]

Something like this

[TY REX]

Something like this

I think you're right. A buddy of mine said the same thing. I'll get the puller.

[intimdatr]

Id bet the diode is full of schmoo. Clean and see if it holds before throwing parts at it. 

Edited June 17, 2018 by intimdatr

[TY REX]

Id bet the diode is full of schmoo. Clean and see if it holds before throwing parts at it. 

Interesting, what/where
is the diode?

[intimdatr]

A diode is a device that allows energy to flow one direction, and not the other. In this case, the mechanism that allows the start to "override" and disengage from the stator is a mechanical diode. Some may call it the starter clutch, but its not really a clutch IMO. 

There is what kind of looks like a needle bearing that rides between the flywheel and the starter gear. If the needles get pack full of grit they won't bite the flywheel (and thusly the crank) and lock up allowing the starter to spin the engine and start it. 

Ill go grab a picture of mine since its all apart.


Edit: part number for reference:  5UM-15570-00-00 

Edited June 17, 2018 by intimdatr

[intimdatr]

Here are some quick pics of what im talking about. 1st is the starter gear, and second is the flywheel and the diode/clutch.