# Yamaha 50 2 stroke running issue



## Palmbeach757

I have a 2005 yamaha 50 2 stroke, I have been through these carbs as they were filthy and cleaned them as I have a thousand other carbs and successful. These had rubber plugs(cabs) over the jet in the bottom. I didnt put them back in thinking I may get a little more umph out of this thing and it runs great until you try to get her up on plane. Then she misses something terrible and wont accelerate to full rpm's. Does great in neuteral but under a load she is a dog. My question is.... I'm not familiar with needing these caps and what are they for and is that my reason for the chitty running. I took off the spark arrestor and it seemed like it was getting a little more air and running a little better but no cigar. Can I adjust fuel/air mixture screw to offsetmaybemorefuel by removing the plugs. I'm really trying to keep from removing these carbs again wifi can help it. Thanks I advanced further help


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## Palmbeach757

I have a 2005 yamaha 50 2 stroke, I have been through these carbs as they were filthy and cleaned them as I have a thousand other carbs and successful. These had rubber plugs(cabs) over the jet in the bottom. I didnt put them back in thinking I may get a little more umph out of this thing and it runs great until you try to get her up on plane. Then she misses something terrible and wont accelerate to full rpm's. Does great in neuteral but under a load she is a dog. My question is.... I'm not familiar with needing these caps and what are they for and is that my reason for the chitty running. I took off the spark arrestor and it seemed like it was getting a little more air and running a little better but no cigar. Can I adjust fuel/air mixture screw to offsetmaybemorefuel by removing the plugs. I'm really trying to keep from removing these carbs again wifi can help it. Thanks I advanced further help


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## backcast

Following


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## backcast

I have 2009 yamaha 50 2 stroke. Contemplating doing carbs myself. I looked at YouTube and seems like only 2 main jets.
Joe


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## DuckNut

Sounds like your high speed jets are still clogged.

Try an ultra sonic cleaner.


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## Palmbeach757

DuckNut said:


> Sounds like your high speed jets are still clogged.
> 
> Try an ultra sonic cleaner.


So are the rubber caps important in The carb


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## DuckNut

Palmbeach757 said:


> So are the rubber caps important in The carb


I have no idea.

@Cut Runner is a certified Yamaha dude. He could help you out.

A motor that is not under load won't need the secondary jets to work properly to get the rpm's up. But when under load they are a must.

No clue what the caps are for. Were they covering or plugging an orifice?


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## NativeBone

I beleive @Palmbeach757 is describing is the rubber cap that is installed over the pilot jet.


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## Palmbeach757

NativeBone said:


> I beleive @Palmbeach757 is describing is the rubber cap that is installed over the pilot jet.
> 
> View attachment 135454


Correct


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## NativeBone

https://forums.iboats.com/forum/eng...ki-outboards/362257-rubber-plug-over-carb-jet


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## Palmbeach757

NativeBone said:


> https://forums.iboats.com/forum/eng...ki-outboards/362257-rubber-plug-over-carb-jet


That kind of confirms my theory on that


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## JC Designs

The plugs are needed. There are 3 circuits in those carbs and without the plugs you are bypassing the intermediate circuit basically flooding the engine before it can build any power or rpms. @DuckNut, guess who else is a certified Yami tech?


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## DuckNut

@Palmbeach757 

I say put the plugs back in. hehe


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## Palmbeach757

JC Designs said:


> The plugs are needed. There are 3 circuits in those carbs and without the plugs you are bypassing the intermediate circuit basically flooding the engine before it can build any power or rpms. @DuckNut, guess who else is a certified Yami tech?


That sounds like exactly what it is doing, dumping too much fuel and not enough air to compensate. Thanks,.I guess I will order these plugs


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## JC Designs

Palmbeach757 said:


> That sounds like exactly what it is doing, dumping too much fuel and not enough air to compensate. Thanks,.I guess I will order these plugs


You are welcome.


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