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Specific jetting question for my 7R

1034 Views 8 Replies 6 Participants Last post by  jeeps84
I have searched past threads but didn't find anything that specifically answered my question. I have found through various sources that the 7R actually runs rich from the factory instead of the typical lean condition of most sportbikes. How rich, I have no idea but I do know that my 7R will backfire (blue flame out the can) after sitting during high humidity. Now, it is said that adding an aftermarket slip-on, bolt-on, or full exhaust will lean the bike (severity based on type/style/manufacturer). My 7R has a Yosh RS-3 bolt-on.

I was planning on buying a stage 1 jet kit over the winter but what purpose would it serve if I am already running more fuel than air? I am assuming that the purpose of a jet kit is to utilize larger jets (not smaller) forcing more fuel through the carbs to richen a lean condition. Can you go with smaller jets to lean a rich condition? Is it better to adjust the factory jets? I am not sure what I am going to do but I want to fix this over the winter. I am also entertaining the idea of a full (Akra) system with new jetting.
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First of all, the money you spend on a jet kit is not just paying for some are paying for the research and development needed to figure out what taper to use on the needle along with what size main jets to use. Remember that the needle controls most of your fueling for most of your riding conditions so it only makes sense that it's taper be properly sorted. In some cases (not many) the jet kit does use leaner than stock jetting...but even if the main jets are smaller the needle taper could be richer than stock in some locations. However, it is designed to work as a system.

Second, every bike is different. The only way to properly set up the jetting on your bike is to start with a jet kit (I prefer Factory brand for many reasons) and have it tuned using a dyno and some form of exhaust gas analyzer. Anything else is a best guess. If you are considering a different pipe, get it all done at the same time so you have the tuning done with the components you plan on running.

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It's the popping on deceleration which is pretty noticeable (second gear only) and then the pop during start-up. I'll be pulling the tank as well as all plastics in a few weeks or so as my bike will be painted over the winter. I'll pull the plugs at that time and take pictures of each. I'll update this thread accordingly. I was planning on going with the Factory stage 1 jet kit as I have read it is easier to install than the Dynojet.
You'll also want to make sure that the air injection system has been disabled. The Factory directions may include this step, I don't remember for sure, but most Kawasaki's with a pipe/jet kit need this done to prevent most of that backfiring under deceleration.

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