'05 YZ250: Water?

jp2396 · Mar 5, 2005

Hey all,
After washing my bike, it seems like I'm getting a little bit of water in the engine somehow. It starts great, but when I take it for a spin it seems like it doesn't want to rev. After getting on it a little, it clears up and everything is fine. I cover the air filter and have the hose on a low pressure spray. The other reason I think I may be getting water in somehow is afterwards, the power valve vent tube looks to have a very small amount of grayish water dripping out. Again, this only happens after a wash and not during a ride. Any ideas of what I should be looking for? And by the way, the airbox has been sealed and the filter is completely dry, unless it may be sucking up a little leftover water from the bottom of the air box?

Mike's 2003 YZ250 · Mar 6, 2005

Maybe the water is getting in through the back of the silencer?? Thats the only thing I can think of. :think: Try covering the end of the silencer or corking it up while washing the bike. Let us know what happens or what you find out! Mike :cool:

uts · Mar 6, 2005

Check the seal where the pipe goes on to the cylinder.

AfricaOffrd · Mar 7, 2005

Your motor is still cold and probably still running on/off the choke. Give it a chance to warm up.

I blast my 05 model with the pressure washer, and it runs just fine.

jp2396 · Mar 7, 2005

Thanks for the reply's everyone. i did have a plug in the silencer and the pipe looks to be mating properly at the head pipe. Maybe it isn't completely warmed up when I take it down the street. I'll let it run a little longer next time. Again, thank you all for the reply's.

Solid State · Mar 8, 2005

Keep A Close Eye on the Gray Stuff!

jp2396,

My '01 YZ250 has produced that gray stuff out of the power valve vent tube since new. The '05 and '01 are the same motor for all practical purposes. In my case, it is not water from washing - although at one time I thought it was. It's not from condensation either. It is indeed engine coolant that finds its way into the exhaust portion of the cylinder.

Keep a close eye on what comes out of that vent tube. If you ever see anything that is gray (not from washing) - you have a problem. As in your case, I asked myself the same question - if you completely sealed the intake and exhaust and wash the bike with low hose pressure, then how can water get into the cylinder?

Hopefully, you are inhailing some water from washing - perhaps from the bottom of the airbox as you have suggested. But if you've ruled all else out, and you notice any gray junk out of that vent tube (even a small amount) especially without washing the bike, then post here immediately and I'll try to help you.

Good luck.

jp2396 · Mar 9, 2005

Solid State,
Thanks for the info on the "gray stuff". I have only noticed the gray stuff after washing the bike, and never during any type of riding. Maybe the air box/carb seal is not seating properly or the carb/intake seal? The coolant level in the radiator looks good too. Could it be an overflow of unburned mixture? The bike starts right up, no problem. The engine also has only 3 hrs. on it (bought it brand new in January) and I was pretty easy on it during the break-in. Does your '01 still do this or were you able to prevent it from happening? If you did correct it, what was involved? Thanks in advance for your advice.

Solid State · Mar 9, 2005

jp,

You should see smoke or unburned fuel or a combination of both, but not grey. Grey out that vent means water is mixing with unburned fuel mixture. If it only ever happens after washing, then its hose water and not a problem.

There are only two other members on this board to document this condition in the last three or four years. In my case, there is a transfer of pressure between the coolant system and the rest of the cylinder. I have confirmed this with a radiator pressure tester. Eric Gore has advised me with this problem in the past.

This 'leak' between the systems can only happen in three areas - the head, cylinder or cases. The leak does not have to be very big to produce the grey spooge. In my case, the slight drop in coolant level is only detectable after a weekend of racing where only a small top-off is needed. You will not notice a coolant level drop with just 3 hours on the motor unless you are riding WOT.

So far, I have over $700 invested in solving it (sort of) and no it isn't fixed. Last season, I ignored it and just raced. The leak does not seem to effect performance. If I go for the over-bore on the original cylinder, then I would want to send the motor to Eric this time (instead of who he recommended) and have him and Rich tear it apart and fix it.

Do me a favor and let me know if you see it without washing.

jp2396 · Mar 9, 2005

Solid,
I'll keep an eye on it. I went riding over the weekend and didn't have anything in the bed of the truck or on the garage floor, so I'm going with your assessment of hose water. I'm thinking maybe a little is getting into the vent hose when spraying the underside, then when the engine is started, the exhaust is pushing it back out. If it does start leaking when I haven't washed it, I'll post a note for you. I really appreciate your replys on this.

stan921 · Mar 11, 2005

I recently started getting some grey sludge out of the power valve vent on my 2000 yz250. I noticed it immediately after changing premix oils. I used to use Castor 927 but thought I would try the Mobil MX2T. I haven't switched back yet to see if that is the reason. I mechanic I asked about it said it was normal. Still, it give me pause for concern.

'05 YZ250: Water?

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