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2006 V50 T5 6spd Manual
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Discussion Starter #1
This has to be something little or basic. I recently acquired an '89 Yamaha YFM200 DX Moto 4 from my grandfather since he upgraded to something bigger and smoother.

Basically, I can drive around a little, and it runs like a champ. Then it bogs, and I have to give it a little choke for it to do anything but idle.

When I start slowing down is where it bogs, then I'm flicking the throttle trying to get it to accelerate again. Any ideas?

http://www.youtube.com/watch?v=Lt6TrmXNqP4
 

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2006 V50 T5 6spd Manual
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Discussion Starter #4
Have you checked the basics? Make sure the carb boots have a good seal, your fuel lines are in good order and the air filter is alright?

Also, has that thing sat for any length of time? You jets might be clogged.

PS - Karla and I are jealous that you have a quad!!
Checked the carb boots, fuel lines are fine, it has what appears to be a pretty new filter. The air filter is funky (foam is old and nasty, cleaned it up some). Runs just the same without the filter though. Never sat for more than a couple days at a time, he drove it almost daily to go get the mail, etc...


Haha. This is my new project quad! The one that you see at the end of the vid is my 'nice' one. '02 Polaris Magnum 325 4x4 (Mossy Oak Edition with winch, bumpers, etc...). My grandfather replaced the Yamaha with an '02 Sportsman 500 H.O. with independent rear suspension. That thing is sweet!
 

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2009 Forester X Premium
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Carb needs cleaned out, you can either remove it and clean it or run some Seafoam thru the gas tank and that may clean it up without removing anything.
 

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2006 V50 T5 6spd Manual
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Discussion Starter #7
Carb needs cleaned out, you can either remove it and clean it or run some Seafoam thru the gas tank and that may clean it up without removing anything.
Yeah, it has a regular diet of SeaFoam. Will probably have to pull the carb off and clean it, I suppose.
 

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An ATV this old is likely to have multiple problems. Here's what I think may be going on.

1. The oil is contaminated with fuel from an overflowing the carb due to a stuck float and leaving the fuel petcock open or just from lack of oil an change.
2. The choke jet in the bottom of the carb float bowl is clogged.

That will make it start easily cold even if the choke (enrichener) jet in the bottom of the carb bowl is clogged. When the engine gets warm though the fuel is boiled in the crankcase and makes the engine run too rich. Using the choke (really an enrichener circuit) opens up an air passage which, because the enrichener jet is clogged, actually makes the engine run leaner because it's not pulling up any fuel to mix with the extra air.

I know it seems counter intuitive but I've seen the scenario above several times.


So I'd do this.
1. Change the oil and filter
2. Replace that air filter element
3. Clean the carburetor thoroughly. (Skip the Seafoam)

Guy
 

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2006 V50 T5 6spd Manual
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2,519 Posts
Discussion Starter #10
An ATV this old is likely to have multiple problems. Here's what I think may be going on.

1. The oil is contaminated with fuel from an overflowing the carb due to a stuck float and leaving the fuel petcock open or just from lack of oil an change.
2. The choke jet in the bottom of the carb float bowl is clogged.

That will make it start easily cold even if the choke (enrichener) jet in the bottom of the carb bowl is clogged. When the engine gets warm though the fuel is boiled in the crankcase and makes the engine run too rich. Using the choke (really an enrichener circuit) opens up an air passage which, because the enrichener jet is clogged, actually makes the engine run leaner because it's not pulling up any fuel to mix with the extra air.

I know it seems counter intuitive but I've seen the scenario above several times.


So I'd do this.
1. Change the oil and filter
2. Replace that air filter element
3. Clean the carburetor thoroughly. (Skip the Seafoam)

Guy

Thanks for all the tips, Guy! I'll get on it as soon as I get back from our Christmas trip. :biggrin:

-Zach
 
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