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Xr 400 Carb Probelm

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I bought a 2001 xr 400 wtih a White Bros exhaust and was re-jetted to 58/162. The bike was hard to start and would backfire on decel, old gas. Decided to clean carb, took it off the bike and cleaned it. The bike now starts on the first kick and idels great. However, I have a new problem, at about half throttle to top end the engine does nothing but sputter, sputter, sputter, no power. Help please!!!!::applause:

Any ideas/suggestions would be greatly appreciated.

Thanks !!!!

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I bought a 2001 xr 400 wtih a White Bros exhaust and was re-jetted to 58/162. The bike was hard to start and would backfire on decel, old gas. Decided to clean carb, took it off the bike and cleaned it. The bike now starts on the first kick and idels great. However, I have a new problem, at about half throttle to top end the engine does nothing but sputter, sputter, sputter, no power. Help please!!!!::applause:

Any ideas/suggestions would be greatly appreciated.

Thanks !!!!

Your main jet sounds too rich to me for a stock engine, this is probably whats causing the stutter. The XR4 is quite touchy with its jetting. I had a 2000 XR4 running a full staintune exhaust and i ran 55/158 jetting, this was the best combo for me.

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If your going to keep that exhaust, make sure you have the snorkle pulled. I'm guessing you're pretty close to sea level. I agree about the main being slightly to rich. Try the 158-160 and be sure to check where the needle is set. I think stock needle height, even for a Ca bike is middle position.

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Thanks. I will try smaller jets give the 55/158 a try. I am at sea level and the snorkel has been pulled. Too bad the bke shop is closed today!!

The air box is dirty but I can not figure out how to remove it any suggestions?

Do you think my problem could be something other than the carb?????

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I don't think you're too rich for sea level unless it's really hot there. 62/162 is stock with the baffle pulled, which is about where you're at. Get a Factory Service Manula and read chapter 5.

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Could it be petrol starvation ? Is your fuel pipe kinked, or the float stuck in the up position. Or is the choke not coming fully off (off is down on the lever).

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Well, I took the carb apart again to make sure there was no dirt in the jets, all clean. Plenty of gas in the bowl. Choke working well, no porblem there!!!

Will keep trying to fix it . I want to RIDE!!!!!!!!!!! Getting frustrated!!!!

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I have 03 xr400 and just did the gordons mods....jetting at 155/55...starts easily and runs great...just got back from gorman and man what a difference.

In addition to pulling the snorkel i cut out more plastic under the seat.

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I have 03 xr400 and just did the gordons mods....jetting at 155/55...starts easily and runs great...just got back from gorman and man what a difference.

In addition to pulling the snorkel i cut out more plastic under the seat.

Glad to hear the mods worked for you and the jetting accurate for Gorman :applause:

Tony

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If it is mid-throttle and it clears up at full throttle, then it could be the needle or clip setting.

You can jet these bike horribly wrong and they still run great.

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The probelm starts at middle throttle and does not clear at full throttle...

In fact adjusting the fuel air screw in or out makes no diffrence.

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The fuel screw will not make any difference in how it runs in the mid to full throttle range. When you adjust it trying to clear up that range, all you're doing is messing up your off idle response and slow circuit.

Does that exhaust have a packing? If it's blown, the bike won't run at hi throttle openings.

Are you shifting up when you should and not winding it out, hitting the rev limiter? There was someone on here doing that once, he wouldn't shift.

Make sure the fuel tank cap is venting freely. Next time you run at hi throttle and it starts cutting out, stop quickly and remove the fuel cap, see if you get a "whoosh" of air.

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Thanks I not familar with this bike or with a rev limiter. After I clean the carb I started the bike and just gave it thorttle but did not ride it because it seemed to have no top end... rev-limiter????

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The rev limiter is a circuit in the CDI that prevents the engine from being revved/run beyond a certain RPM. When your RPMs hit that point, the CDI basically cuts power to the ignition. It's a safety thing to keep you from revving an engine beyond it's design limits and capabilities.

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Ok, after many days of frustration I decided I needed to consult a repair manual. Of course, I did not have so I did the next logical thing to do I ordered one, it's in the mail. Desparate , I went to the public library and found a manual in the reference section, no check out allowed. So there I sat and read an read lookin for answers, hope!!

EUREKA!!! I think I found out what I did wrong. There is a small tube that connects the carb to the pulse gererator which I did not connect. PENDEJO!!!!!! So now this Friday I will connect it and see if it works...

Wish me luck...

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There is a small tube that connects the carb to the pulse gererator which I did not connect.

...

I can think of no such thing on the stock carb. The only "tubes" coming off the carb are the fuel line and vent lines.

And what are you calling "the pulse generator" ?

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I can think of no such thing on the stock carb. The only "tubes" coming off the carb are the fuel line and vent lines.

And what are you calling "the pulse generator" ?

I'm trying to figure this out too... What the hell is he talking about...? :applause::lol:

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EUREKA!!! I think I found out what I did wrong. There is a small tube that connects the carb to the pulse gererator which I did not connect. ...

???????????????????????

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Here is what I know. According to the Haynes xr 250/400 workshop manual the carb has a vent tube that attaches to the pulse generator. I found this information in the ignition section take a look!!!! The guy at the Honda dealer told me the pulse gererator was an integral part of the ignition system. This part is located on the frame on the left side above the rear part of the engine case. It has a couple of wires that come off of it.. Just follow the vent tube that comes off the left side of carb... see it attaches to anything.... Please let me know what you find. This is a 2001 model...

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