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Drz400SM FCR jetting help

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First off let me say, I've tried searching but I see mixed results to this question.

 

I have a DRZ400SM. When I bought it, it came with a DRZ400S dynojet kit (didn't realize until after). With the 136 main in, it idles perfect but dies with any throttle. I had already pulled it twice so I'm over it and deciding to just get a FCR 39mm to put in instead since I planned on doing it at some point anyways.

 

So my questions would be, living at sea level, should I buy the jd jet kit with it? Should I change the jetting before installing? Should I do the "o-ring mod" (this one has a lot of back and forth from what I see)?

 

Basically I'm asking what would be the best set-up for a DRZ400sm with full two brothers exhaust and the 3x3 mod be?

Edited by MoreBassXD

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Morebass , I would say that the mikuni is cutting out because the dynojet kit does not come with pilot jets , so if this isnt set right the engine cuts out from idle when you twist the throttle . The FCR/MX from TT is a bolt on product , it should be OK out of the box . Just check your jetting when you get it and the needle , it should be a 160 main and an emn needle on the 3rd clip . The o-ring mod is only neede if the pump arm doesnt contact the plunger , nearly every new carb is OK . You do not need to buy a jet kit for it and the only thing you will need to do is set the idle mixture screw once it is fitted and running , so an extended screw will help ( a lot ) . If you are buying a slant FCR from sudco then you will have to tweek it and if you buy secondhand , then its buyer beware and you are on your own , greg

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Morebass , I would say that the mikuni is cutting out because the dynojet kit does not come with pilot jets , so if this isnt set right the engine cuts out from idle when you twist the throttle . The FCR/MX from TT is a bolt on product , it should be OK out of the box . Just check your jetting when you get it and the needle , it should be a 160 main and an emn needle on the 3rd clip . The o-ring mod is only neede if the pump arm doesnt contact the plunger , nearly every new carb is OK . You do not need to buy a jet kit for it and the only thing you will need to do is set the idle mixture screw once it is fitted and running , so an extended screw will help ( a lot ) . If you are buying a slant FCR from sudco then you will have to tweek it and if you buy secondhand , then its buyer beware and you are on your own , greg

Thank you. I'm ordering the fcr now. The only thing I'm curious about is what you said for the stock pilot jet..... If it runs perfect with stock jetting, why would the pilot be an issue with the bigger main in? Aren't they controlling different power bands?

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I`m guessing the 3x3 and pipe are on the bike already with the rejetted mikuni ? If it is then you either need an extended fuel screw or bigger pilot jet . I have been through this before with other bikes and it was from too small a pilot jet . The carb works by vacuum and air pressure and once you change the volume of the intake flow you have to rejet for that aswell ( pilot circut/idle circut ) It cant get enough fuel on the transition from the idle to going onto the needle and it cuts out . It works like if you wind up the idle to miss the flat spot or feather the throttle so you dont drop the airflow too much . Its easier to rejet , greg

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