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Motor sputters when I open the throttle

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I have a 2000 XR400 that I bought new. I haven't had a chance to ride it very much lately so it has been sitting for a while (2-3 years). I got it out a few weeks ago, pulled the carb off, cleaned the float bowl and the jets, and it started right up. It starts easy and runs pretty good at low rpm, but when I open the throttle it sputters and chokes, then eventually kicks in a provides some power. It seems like a carb problem to me, but I don't really know. I have been thinking about getting one of those mikuni pumper carbs from XR's Only. Do you think that will fix my problem?

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Did you take the fuel screw out and clean that passage? Make sure the o-ring is not shot. Are you still using 2-3 year old gas in the tank?

Edited by Trailryder42

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TR is right and also check that during the carb cleanings the float level was not accidently changed. Another thing you may have overlooked, is along the side of the pilot jet there are four rows of fine holes that may be blocked. On some carbs the needle jet holder also has those fine holes that get blocked too.

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Thanks for the replies. I did put new gas in the tank, but I guess I didn’t do a good enough job cleaning the carb. I just soaked the jets, not the body, so there are probably still some plugged holes. The o-rings are original, so they could definitely stand to be replaced. I will also check the float before I put it back together next time. I may have knocked that around when I took it apart.

Should I get one of those carb rebuild kits, or just the o-rings?

-OR-

Should I just get a new carb, or will that just be even more work to get it set up right.

I will only be able to ride about 10-12 days this year, and probably never much more than that, so I value-low maintenance over performance.

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I'd say if the carb body wasn't corroded from leaving fuel in it that long, it should clean up well. Should be able to get by with just the o-ring package.

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I have the same exact problem with my xr250, except I have a tm34 mikuni flat slide carb hooked up.

Can somebody please confirm, is this a jetting problem or do I have a carb that needs to be rebuilt/ cleaned?

Edited by Mikepagjr

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When I see posts like, "It ran great before I put it away six months ago." I tend to think it is bad gas and the carb is gummed up.

These days, if you are not going to ride for a couple weeks, it might be a good idea to drain the float bowl. The new E10 gas just eats up jets. Though you can clean them, new pilot jets seem to just work better. I had to replace them in my XR80 and XR100 after sitting all winter. That never was a problem before, but it is now with the new gasoline.

Street performance shops seem to be better about having jets in stock than dirt bike shops.

This shop is a mile from my house. They are very helpful when I walk in. The have an XR400 jet kit. Or did.

http://www.factorypro.com/

Found parts for my Mikuni here. They have a $100 clean and rebuild service.

http://www.power-bar...vlet/StoreFront

Under $4, but you pay for shipping until you hit 100.

http://www.rockymoun...ihin-Pilot-Jet-

Edited by Kev_XR

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