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Converting pumper carbs to gravity


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You could have saved yourself a lot of work and just drilled the hole through the needle valve housing a little bigger, then counter-sink it to give the needle valve a surface to seal on.  Also, don't forget to remove the angled supply hose barb and install a straight one.  The factory hose barb that comes on pumper carbs will screw you over if you are trying to gravity feed them.

 

If you look at the pics of the gravity seat vs. the pump seat you will see a groove cut around the outside and two holes drilled through it. The pump seats do not have this. There is no way to get the seat out and modify it without trashing it. So just drilling a hole and counter sinking it will not work. That would be "ghetto-rigging" it.

 

Pumper seat on the right

20130611_105437_zps2d9bbbbc.jpg

 

Gravity seats

 

20130610_164727_zps7d8a750b.jpg

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I went through the same deal. Got hosed on pumpers that were labeled gravity. Then couldn't give the damn things away. Finally almost did then pieced together a set of gravity feed. What a pita. Thought about doin this but wasn't sure I wanted to source the brass stuff. Woulda been easier in the long run prob.

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I went through the same deal. Got hosed on pumpers that were labeled gravity. Then couldn't give the damn things away. Finally almost did then pieced together a set of gravity feed. What a pita. Thought about doin this but wasn't sure I wanted to source the brass stuff. Woulda been easier in the long run prob.

I came out significantly less then a new set of 39 's . Had fun doing it and hopefully help some other's out as well

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Oah yeah, totally a great idea when your on a budget, not hating on that at all - like you said it could be an easy sourced carb & cheap. 

 

16 miles today on the banshee went fine. I got to ride to work ;)

 

I should get some temp indicators... or atleast egt's

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Oah yeah, totally a great idea when your on a budget, not hating on that at all - like you said it could be an easy sourced carb & cheap. 

 

16 miles today on the banshee went fine. I got to ride to work ;)

 

I should get some temp indicators... or atleast egt's

So you get to ride on the street huh?  Bet thats hell on the gas pump. Wish we could make em street legal here. I would love to rip a banshee around the streets legaly.

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  • 3 weeks later...

I did some trail riding this weekend and after some spirited climbing/hills (2nd gear spinning & clutching up a long hill) I wouldn't be able to slip the clutch enough to take off if I stopped... It literally runs out of gas. The 1.5 pump needle is definitely small for hill climbing. For street / dirt it is just fine for 60mph crusing gravity fed. I think its when the stock tank gets to about 1/2 full as it didn't do it from the get go.

food for thought on this topic.

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  • 4 years later...

Thanks!  Different direction that I was wanting to go, though.  I bought a “set” that wasn’t. One is pumper, and one isn’t. Was considering converting the pumper to gravity. Might just chalk it up and buy a real set.  

Edited by DW28
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