HP carb tuning question

Johnny trigger

New Member
Jan 22, 2020
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Hey guys
I have an HP carb and offset intake. Fuel leaks out around the carb to manifold connection. i assume its from the jet being to big? Or could it be from the carb not being completely level? Either way i switched the jet from the stock carb and its slightly better.
I have a 20 piece jet kit but im not sure which jet size comes in the 2 different carbs so im not sure where to start. Neithter have any marks on them.
Thanks for ypur help
 
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kelly dean

Active Member
Oct 3, 2019
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If fuel can leak from that connection then air certainly will and thats a very bad situation, and you should address that issue first you can cause serious damage running to far lean. If your refering the sha clone carb that is commonly called the high performance carb it should have plactic insert in it to fit tight at the manifold. I've included a pic of the SHA clone for reference, If thats the critter your talking about then the stock jet should be a 70
 

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Johnny trigger

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Jan 22, 2020
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Yes thats the one. The plastic sleeve is installed and tightened up. Still leaks fuel around there. I have te NT jet in it.Should i down size the jet some? Plug was oiled up a bit.


If fuel can leak from that connection then air certainly will and thats a very bad situation, and you should address that issue first you can cause serious damage running to far lean. If your refering the sha clone carb that is commonly called the high performance carb it should have plactic insert in it to fit tight at the manifold. I've included a pic of the SHA clone for reference, If thats the critter your talking about then the stock jet should be a 70
 
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kelly dean

Active Member
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from my experience the NT is a far better carb and very much more tunable as it can be jetted as well as you have the needle adjustment the only adjustment on the SHA is to jet other than idle adjustment. That being said I've seen considerable back fueling with the SHA , if the plug is oily then yes jit running rich but as for that what mixture are you running ? But once again the leak at the mainifold should be your prime concern to begin with after that you can begin to dial it in. There is no certain formula for that there are to many varibles.. altitude the air your particular engine setup, when i last ran a SHA it worked best for me with a 68 jet im at basically 1000ft elevation and temps in the upper 70s running a 40to1 mix.
 
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Johnny trigger

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Jan 22, 2020
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I put original manifold and original carb with .68 jet. Sealed everything up good.20-1 gas with yamaha 2 stroke oil.(still newer engine)... starts and idols perfect. And goes near 40mph.. im happy... thanks for your help.
 
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kelly dean

Active Member
Oct 3, 2019
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kentucky
the NT is a much better carb.. i used the clone awhile just because i had it and have since went to a NT on that bike. glad it's worked out for you trigger.. happy trails.. kelly
 
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