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Emision Test & Mikuni Carb


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I put a Mikuni carb on my 00'XR400 last year and now it won't pass emmision this year. It failed twice. The second test I leaned out the fuel screw and turned down the idle air to the point it runs like crap, stuttering and missing. Still failed CO emissions.

Now I have to pay another $19.00 for a 3rd re-test. I only get two tests for my 19 bucks.

So before I put the old OEM carb back on just for the day, are there any additives I can put into the gas to lower emission of CO? I've heard alcohol burns clean and might work but don't know what ratio would be to much.

I got one shot at this cause I'm not going to pay for a 3rd time. Sharing any experience with this would be appreciated.

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I put a Mikuni carb on my 00'XR400 last year and now it won't pass emmision this year. It failed twice. The second test I leaned out the fuel screw and turned down the idle air to the point it runs like crap, stuttering and missing. Still failed CO emissions.

Now I have to pay another $19.00 for a 3rd re-test. I only get two tests for my 19 bucks.

So before I put the old OEM carb back on just for the day, are there any additives I can put into the gas to lower emission of CO? I've heard alcohol burns clean and might work but don't know what ratio would be to much.

I got one shot at this cause I'm not going to pay for a 3rd time. Sharing any experience with this would be appreciated.

There is a reason the xr4 came extremely restricted and really leaned out. if you want it to pass you will probably have to either rejet the mikuni or throw on the stock carb with close to stock jets. you got be careful if you have an aftermarket or modified stock exhaust so that you don't burn the valves running it it that lean. My sax teacher has an off road 1.3L suzuki samurai that as a 1.6L supercharger on it (👍) with a big webber carb on it. He has to changes the jets in it to the point where it will hardly get out of it's own way to get it to pass.

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Just remembered that the gas I used for the test (the XR tank was near bone dry) was from a different county where they sell real gas as opposed to the big city, save the planet gas mix my county sells. Might have something to do with this fail. Anyways Wikipedia has a lot to say about gasohol. Gonna make my own concoction. 👍

Mikuni 36 Jetting 130/15

PO done Gordan Mods

Sparkplug DPR8Z

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