dead in the water

i'm having a problum every time i go through water that is up to the skid plate my 1999 yz 400 spits sputters caughs and dies ive checked all the usual stuff i can't get it to happen when at home buy spraying everthing with a garden hose the bike is all stock i've had this problum sence i baught the bike new. any ideas

What comes to mind at the moment is that maybe a carb vent line is either crimped or partially plugged. Check all 4 vent lines all the way from the carb, making sure that none are pinched, and that the ends aren't clogged with mud. Most guys cut the ends at an angle to reduce the chance of them becoming clogged. The cylinder head vent tube shouldn't cause this problem while the engine is running, but it's possible to suck water up thru it if you stall the engine and restart it in water or mud that is deep enough to come over the end of that tube.

We go through a water crossing about footpeg deep level and my '99 will stall every time. I finally traced it to the pink carb vent hoses.... if I pull them up above the water level before I cross it doesn't happen.

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MotoGreg - flipa.gif

'92 GSXR 7/11 (Until I get a groovy 996 or GSXR1000)

'99 YZ/WR400F 'cause thumpers rule and two strokes drool!

Originally posted by yzf:

i'm having a problum every time i go through water that is up to the skid plate my 1999 yz 400 spits sputters caughs and dies ive checked all the usual stuff i can't get it to happen when at home buy spraying everthing with a garden hose the bike is all stock i've had this problum sence i baught the bike new. any ideas

If you don't want to be stalling your bike thru deep puddles you need to route 2 of the 4 carb vent hoses up near the top of the frame. If all 4 vent hoses are submerged in water the carb can't suck fuel and the motor WILL stall. Use the 2 that go up and over the carb. I run mine up behind the upper shock mount. I also cover them in cloth or foam for added protection.

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YZ A

'96 YZ 125

'99 YZ 250

'01 YZ250F

Most of us don't run the YZ in deep water. You don't usually encounter that in M/X.....maybe some deep mud at times. Looks like it would be a good idea to reroute those vent hoses. You could get a few "Tee's" and route one end downward normally, and the other could be routed up under the seat. No way could the line get obstructed.

I've seen some guys in the past (2 strokes, I can't see why it wouldn't work on a 4 stroke) use a T in their carb vent hoses as they come out of the carb and split the vent into one hose going up and one going down. Then they run one set of hoses up under the tank/seat and the other down the usual route. This way anything that comes out of the carb will go down and air can still get in even if the bottom is plugged.

sounds like my problum is the carb vent hoses i'll try to route them in a different way. thanks for the advice

Boit

I agree that the MX track don't usually get deep water, but that's not always the case. Besides, some of use YZs for off-road activities too.

You don't have to install "Tees" on the newer YZs, Yamaha already ran four lines for you, unfortunatly they sent them all down under the bike. The stock length vent lines were barely six inches off the ground on my 250F. Move two up high and it will run in water up to the air filter. :)

One other thing. If you are going to be doing a lot of deep water crossings you might want to run the trans. vent up high too. You don't want water entering there either.

Originally posted by Boit:

Most of us don't run the YZ in deep water. You don't usually encounter that in M/X.....maybe some deep mud at times. Looks like it would be a good idea to reroute those vent hoses. You could get a few "Tee's" and route one end downward normally, and the other could be routed up under the seat. No way could the line get obstructed.

YZAbuser: Yes, what Iwas getting at is that the bike should be setup for how it will be used. I suppose that since it's intended us is M/X, those low hanging vent lines aren't an issue. Once you start off-roading going across streams, you need to re-route those lines.

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