Carb jetting question ?

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pearljam724
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Suzuki 2-Strokes: 75- GT 550 / 76- GT 750
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Carb jetting question ?

Post by pearljam724 »

Its been a few years since I rejetted a carb and cant remember if jet number size increase is a larger hole for more fuel or lower jet number ? For example, does a 120 jet supply more fuel than a 115 ? Larger number, more fuel ? Or is it lower number jet size, more fuel ? Talking about main jet.
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Zunspec4
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Suzuki 2-Strokes: T500R, SV1000S, TS125, Seeley T500
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Re: Carb jetting question ?

Post by Zunspec4 »

The higher the number the bigger the jet i.e. A 120 jet flows more fuel than a 115.
pearljam724
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Posts: 1681
Joined: Tue Jul 24, 2012 11:45 pm
Country: U.S.
Suzuki 2-Strokes: 75- GT 550 / 76- GT 750
Location: SW PA

Re: Carb jetting question ?

Post by pearljam724 »

Thank you, that’s what I thought. Long story short. Im working on a gs model that is suppose to have 115 mains. The previous owner modified the exhaust and its running leaner than it should. I bought 120’s. Disassembled carb, removed what appears to be the 115 mains, I can only make out the 5 on each. Comparing them with the 120’s I just bought, unless my eyes are playing tricks on me. The ones originally installed appear to be bigger than the 120’s ? Who knows, maybe the guy that hacked the pipes drilled the holes larger in the 115’s ? Its a 4 cylinder, he had each pilot screw all over the place in amount of turns. 2 cylinders were lean and the other 2 were barely acceptable. The only way to correct things to improve things, is to start tuning it based on the 120’s I installed and correctly adjusting the pilot screws based on plug readings from here on out. I wouldn’t think any set of carbs should need any larger mains, with a hacked end of exhaust. Than 2 steps up. Which the 120’s are. We’ll see.
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