Buying a carb

boater1234

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[FONT=&quot]I just bought a used 25hp carb for my 20hp merc to upgrade power and a bit of wot. My biggest thing is when buying a used carburetor is it usually worth it? I'm going to completely rebuild it from the bottom up. I'm going to clean and replace everything. My question is ,is there anything I really need to worry about buying a used carb? I bought it from eBay and has a 30 day money back guarantee to. The carb came off another 25hp 2 stroke mercury that was running but lost compression according to the ad. The carb came off a 94 engine and mine is a 93 so that worked out nicely. Good thing is his feedback is 100% so that says something I would guess. He runs like a salvage yard but sells a ton of parts on ebay. I paid $90 for it so I think I got a great deal. I wanted new but merc said they are so far on backorder and are $330. It could be a long time before they come off backorder and I mean no one has one in stock new or used as this one just popped up recently. I'm guessing if I rebuild everything from top to bottom it should be ok. Good thing is my 20hp carburetor is identical except the bore which is the only difference. I can take everything from my 20hp carb if needed and use it on the new one I'm getting if needed. Any info on anything I should look for when I get it would be great. I would think carbs are pretty tough and not much goes wrong with them besides the rebuilding parts I'm installing.[/FONT]
 

gm280

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You should be good to go after rebuilding it. The usual things that need to be careful of is the adjustment needle(s) and the butterfly plates and shafts. If the carb has been well used, there can be a lot of butterfly shaft (throttle shaft) air leakage. And that is because the shaft wears and allows air to be sucked in. And that usually makes them run iffy if there is a lot of wear. Other then that, not much more if the needle and seat are replaceable. If the PO turned the adjustment needles in too far, that passage can be damaged, but that usually doesn't happen with most carbs either. I think you will be okay. I would however buy a carb kit and go through it well. JMHO
 

boater1234

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Yes sir,that was the fist thing I did after getting it was buy the big repair kit ,not the diaphragm kit,the whole kitten Kaboodle,lol. So how would I know if the butterfly was bad,anyway to tell just by looking at it? This guy is a salvage guy on ebay and like I said has 100% perfect feedback selling tons of parts so I went with it. I usually buy new but trying to find this carb new is I tell u impossible as I called over 200 places that I could find numbers for and I called merc themselves and they said it could be a very long time as they have been on backorder for mths and show no release date on them. I almost got lucky,I missed a brand new one by one day a week ago,other than that, I would have better luck hitting the power ball then finding this carb,lol,as of now and anytime soon anyways. All I can do is hope for the best. He said it came off a good running engine till the compression went kaput on it so I hope it's in good shape. From what I can see it looks good.
 

gm280

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Yes sir,that was the fist thing I did after getting it was buy the big repair kit ,not the diaphragm kit,the whole kitten Kaboodle,lol. So how would I know if the butterfly was bad,anyway to tell just by looking at it? This guy is a salvage guy on ebay and like I said has 100% perfect feedback selling tons of parts so I went with it. I usually buy new but trying to find this carb new is I tell u impossible as I called over 200 places that I could find numbers for and I called merc themselves and they said it could be a very long time as they have been on backorder for mths and show no release date on them. I almost got lucky,I missed a brand new one by one day a week ago,other than that, I would have better luck hitting the power ball then finding this carb,lol,as of now and anytime soon anyways. All I can do is hope for the best. He said it came off a good running engine till the compression went kaput on it so I hope it's in good shape. From what I can see it looks good.

If you have any butterfly plate issues OR the shaft problems as well, you can move the shaft around some. It really shouldn't move around other then turn to open the butterfly/throttle plate. The plate should be tight and not moving at all other then with the shaft turning. If the plate is loose, it needs to be tighten. And if it is bent, you will be able to see that. It should be perfectly flat and tight.

I don't think you will have issues from what you stated. I still would install a new carb kit though. That is just a very good precaution and allows you to see everything about the carb. Just a good idea in my book.
 

boater1234

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Should be here tom or Tues so I will check all that. How would I tighten the butterfly plate up? Never done that before. The plate should be perfectly flat so u say,and the shaft should have no play besides opening the butterfly plate. I will inspect it when I get it,ty very much for this info,means allot to me.
 

boater1234

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I have bought many used 25hp mercs and I guess all the carbs were good on them,so the chances are good that everything on the carb is tight and works as it should,100% though I am doing a full rebuild.
 

gm280

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boater1234, the only way the throttle plate could be loose is if it was ever removed. The screws they use to fasten such plates are usually splayed after installed. So all you would have to do is re-tighten them and see if they stay tight. But I really don't think you will have that problem. I only mentioned it because you need to examine the carb before installing it. And since you are going to rebuild it, you will see everything as well. Let us know how it all works out. Pictures are always welcomed as well.
 

boater1234

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Just got the carb today,will post pics. It looks really good from what I can see. I'm tearing it apart next week when I get my carb rebuild kit. As of now we're dealing with a tropical storm so I will wait till that passes. Everything seems to work perfectly on it though.
 

boater1234

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The one thing I never really paid attention to on my 20hp carb was the butterfly plate closes but on an angle due to the throttle only being able to go so far. Is this normal ? Everything seems to function properly though. The butterfly plate closes,but at a slight angle which seems normal.
 

boater1234

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I answered my own question by finding it on YouTube, yes it's normal for the butterfly plate to be at a slight angle when closed .
 
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