Yamaha Big Bear Troubleshooting

[tparente]

I was wondering if anyone could give me some assistance trying to figure out what is wrong with my ATV. I have owned a 1999 Yamaha Big Bear 350 for about a year now and have not had any trouble with it until I decided to let my sister ride it. It was wet and extremely muddy and it did not take her long to roll the bike over. It was upside down for about 5 minutes. I turned the gas off, rolled it back over and let it sit for about 15 minutes. It started right up and ran fine for about ten minutes. After that it has not been right. It ran so poorly that I could not even drive it on to the trailer. Every time I gave it gas it just spit and bogged down. I got it home, opened up the air filter compartment, and it was full of what appeared to be a mixture of oil, gas, and obviously water. I drained it, cleaned the filter, let it dry and re-installed. The bike ran fine for about half an hour after that, and it began acting the same way again. This time when I opened the air filter compartment, everything was clean. What else should I check? Does this sound like carberuation problems, or could it be more in depth? Any suggestions would be greatly appreciated.

Thanks,
Tony

[Snafoow]

Not sure if this is your problem but the engines oil pump picks up oil from the sump at the bottom of the engine. With the machine upside down the oil pump had no oil to pump threw the engine.

Is it knocking or smoking?

Have you drained the carb in case water got in there?

Have you run it with the intake off?

Is there any metallic color in the oil , or on the oil filter?

[The Buck]

Tony
Just wondering how much water did you see ?.
One thing you need to remember when dealing with water.
Is that you can bend a rod real easy if you suck up any fair amount of water in to the cylinder. (Even oil will not compress)

You did not say if she rolled it on dry ground / Mud or water.
Just remember if its in water pull your spark plug & cycle the eng at least 10 rev.
To try to get any water out, put in some type of lube in the cyl then try to start it up. The extra time could same you a ton of money before you start it up.

It ran for about 15 min - that could be 1 carb full at Idle
Pull the fuel line off then open the fuel valve to see how the fuel is flowing.
Then try to blow air lightly in to the carb - recommend to do this with your mouth & a piece of hose to see if the needle is open.
I say start there then get back to everyone

Just my 2 cent's
Brent

[TWIZDdirtRIDER]

its amd at you for lettin a girl ride it

[tparente]

Originally posted by Snafoow@Mar 13 2005, 11:35 PM
Not sure if this is your problem but the engines oil pump picks up oil from the sump at the bottom of the engine. With the machine upside down the oil pump had no oil to pump threw the engine.*

Is it knocking or smoking?

Have you drained the carb in case water got in there?

Have you run it with the intake off?

Is there any metallic color in the oil , or on the oil filter?
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[/quote]

The engine is not knocking or smoking, I checked the oil level and it is at the proper level. I did start the engine yesterday with the intake off, it idled fine, however I did not want to run it for long periods of time like this, or ride it like that either. Once I put the air filter back on, and closed it all up, I rode it and within a matter of minutes it started doing the same thing. There is no metallic color in the oil or the filter.

[tparente]

Originally posted by The Buck@Mar 14 2005, 06:21 AM
Tony
Just wondering how much water did you see ?.
One thing you need to remember when dealing with water.
Is that you can bend a rod real easy if you suck up any fair amount of water in to the cylinder. (Even oil will not compress)

You did not say if she rolled it on dry ground / Mud or water.
Just remember if its in water pull your spark plug & cycle the eng at least 10 rev.
To try to get any water out, put in some type of lube in the cyl then try to start it up. The extra time could same you a ton of money before you start it up.

It ran for about 15 min - that could be 1 carb full at Idle
Pull the fuel line off then open the fuel valve to see how the fuel is flowing.
Then try to blow air lightly in to the carb - recommend to do this with your mouth & a piece of hose to see if the needle is open.
I say start there then get back to everyone

Just my 2 cent's
Brent

How would I know if I bent a rod?* It was muddy, but she did not roll it in water more than ankle deep.* When I pull the fuel line off, and blow air into the carb, what should happen?* Or how can I tell if the needle is open?

Thanks,
Tony
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[macgyver]

check the parking break swich. the one on my wolverine would act up like that now and then. it will knock out your spark like a rev limiter.the quad would hardly run.it started to do this after i flipped the quad.this is a very common problem on a yamaha i ended up un hooking it.

[Snafoow]

Originally posted by tparente+Mar 14 2005, 06:07 PM--><div class='quotetop'>QUOTE (tparente @ Mar 14 2005, 06:07 PM)</div>

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The rod is not bent. If it was it would run poor at idle and revving, Cold or hot. It would have also staled the engine if that much water entered the cylinder for damage like that to happen. It would probably not crank over until the water was drained from the cylinder.

Replace the spark plug with a new one if you haven't already. It may be oil fouled from the bike being upside down.

If still no luck make sure you have good fuel supply and maybe take the bowl off the carb and make sure the float and needle are free and clean and bowl and jets don't have any crap in them.

It isn't by chance a rev limiter shorting is it ? Or maybe a spark related problem?