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Honda Question about jetting

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i got a full system HMF exhaust put on my 300ex. it has been jetted but it back fires alot when i go fast then let off the throttle. i was wondering if this is bad for it and do i just need to get pilot jets?

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You can try adjust the fuel screw "out" if you can or go up 1 size in the pilot jet. Less than 1 turn out means your too fat on the pilot, more than 3 out means too lean.

I hope that helps. :bonk:

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You can try adjust the fuel screw "out" if you can or go up 1 size in the pilot jet. Less than 1 turn out means your too fat on the pilot, more than 3 out means too lean.

I hope that helps. :bonk:

What do you mean less than 1 turn out and more than 3 out? and can you tell me where to find this stuff? i'm not the one that jetted it and i dont even know where the carbuerator is.

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Im not sure if the 300 has an adjustable fuel screw but if you see a small silver cap in front of your main jet cap, remove it and there should be a slotted fuel screw underneath it. You can turn it in or out. In = less pilot jetting and out = more jetting. Backfire on deceleration is a sure sign of lean pilot jetting.

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Im not sure if the 300 has an adjustable fuel screw but if you see a small silver cap in front of your main jet cap, remove it and there should be a slotted fuel screw underneath it. You can turn it in or out. In = less pilot jetting and out = more jetting. Backfire on deceleration is a sure sign of lean pilot jetting.

Yes on the mixture screw. It should not be covered and on the bottom of the carb, engine side of the bowl. I agree on the lean pilot circuit but that quad runs a little lean in the mid as well from the factory so going down a clip on the needle may help things too. Start with the mixture screw first. If you find it and need help on adjusting it post back.

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