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hi all new to the site but been reading everything about carb jetting i can find but still dont really have an answer. i have just bought a new jet kit from sigmaracing. however they sent me 125x2 127.5x2 130x2 and 132.5x2 jets. in the fitting instructions they sent me they are saying to start of fitting the 125 jets to 1&4 carb and fitting 127.5 to 2&3 carb and if thats not right then change up a size (127.5 to 1&4 and 130 to 2&3). might be me but i thought the jets would all have to be the same size in all the carbs for balancing and setup or am i being stupid. or have i just been sent a half set of jets. sorry for the long story but want to try get my bike back together for a rally in couple weeks cheers for any help. sorry forgot to mention my bike is a 1999 RR-X
 

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hi all new to the site but been reading everything about carb jetting i can find but still dont really have an answer. i have just bought a new jet kit from sigmaracing. however they sent me 125x2 127.5x2 130x2 and 132.5x2 jets. in the fitting instructions they sent me they are saying to start of fitting the 125 jets to 1&4 carb and fitting 127.5 to 2&3 carb and if thats not right then change up a size (127.5 to 1&4 and 130 to 2&3). might be me but i thought the jets would all have to be the same size in all the carbs for balancing and setup or am i being stupid. or have i just been sent a half set of jets. sorry for the long story but want to try get my bike back together for a rally in couple weeks cheers for any help. sorry forgot to mention my bike is a 1999 RR-X

Some engines the inner cylinders run hotter than the outers so they run slightly richer jets to cool them.
 

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cool cool did not know that not got a lot of bike mechanics under my belt but am a car mechanic so try to give anything a go. i have a haynes manual but its at work so am in middle of downloading one so have one on computer as well cheers for your reply bladeracer
 

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cool cool did not know that not got a lot of bike mechanics under my belt but am a car mechanic so try to give anything a go. i have a haynes manual but its at work so am in middle of downloading one so have one on computer as well cheers for your reply bladeracer

One of the advantages that bikes have over cars is the ability to precisely tune each cylinder seperately from all the others. Not many cars run seperate carburetors.
 

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hi all new to the site but been reading everything about carb jetting i can find but still dont really have an answer. i have just bought a new jet kit from sigmaracing. however they sent me 125x2 127.5x2 130x2 and 132.5x2 jets. in the fitting instructions they sent me they are saying to start of fitting the 125 jets to 1&4 carb and fitting 127.5 to 2&3 carb and if thats not right then change up a size (127.5 to 1&4 and 130 to 2&3). might be me but i thought the jets would all have to be the same size in all the carbs for balancing and setup or am i being stupid. or have i just been sent a half set of jets. sorry for the long story but want to try get my bike back together for a rally in couple weeks cheers for any help. sorry forgot to mention my bike is a 1999 RR-X
Each bike is going to respond differently to mods, and the air to fuel ratio will vary due to elevation and outside temperature. Best thing to due is start rich and then lean it out until the plugs look good. Black plugs and you are rich, white and clean plugs means you are lean. Also listen for detonation. If it's detonating then you know it's running real lean. Burn premium 91 gas to prevent detonation and a blown engine.
 
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