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Help with Engine Bogs

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I have a "new to me" '05 450x. The engine idles fine but has a terrible bog when you grab a handful of throttle. This occurs sitting still (which I believe to be normal) but more importantly occurs while riding. The bike is completely stock. It ran fine up until the previous owner replaced the throttle with a new one. He said as soon as he did that, the hesitation started and said there may be a problem with the throttle cables. The cables appear to work properly. To this point, I've put a new plug in. cleaned the air cleaner, completely diassembled the carb and cleaned and blew air thru all the passages. I tried raising the needle jet. Checked the valves and valve timing. When I twist the throttle, looking into the carb I can see the accelerator pump squirting fuel into the carb. I don't know what else to check? Could the throttle cables be out of adjustment so bad to throw the Throttle Position Sensor out of whack? Could a bad TPS cause this? The thing I keep going back to is that it ran fine until the throttle was replaced. Any advise would be appreciated. Thanks.

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Sounds like a lean condition. You said completely stock, does that include the jetting and air screw adjustment? These bikes come super lean from Honda to pass smog. Get a J.D. kit, open up the air box and follow the directions. You won't have any more trouble.

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its a condition, Its not a lean but a rich. Its normal with fcr carbs. An easy fix is the boyesen accelerator pump cover. its a fix but not the correct fix. Jd jetting has some sort of ap mod also. Do a search and read the 450r forum

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I forgot to add, hesitation improves when I leave the choke on after warm up. This leads me to believe it's a lean condition....but what do I know. As far as jetting, it's all stock but I did adjust the low speed adjuster. It's about 1 1/4 turns out. I'd have no problem rejetting but like I said previously, the bike ran fine prior to changing the throttle. I don't really see the need for it since it was running fine. I certainly respect everyones help though. Could the throttle cable adjustment cause this? Thanks for your time!

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its a condition, Its not a lean but a rich. Its normal with fcr carbs. An easy fix is the boyesen accelerator pump cover. its a fix but not the correct fix. Jd jetting has some sort of ap mod also. Do a search and read the 450r forum

Uh, no, don't think so.

Leany weany chilli beany is more like it.

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if it gets better with the choke on then it is most certainly lean. rejet that thing and be happy.

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Sorry to be such a hard head.....but it ran fine before the throttle was replaced. I'd hate to rejet if that's masking the original problem. I'll research the JD jetkit however. Thanks for the help

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Did you actually get to hear the bike run prior to the throttle cables being replaced ?

Like others have said, the bike comes very lean from the factory. An off idle bog on acceleration is a classic sign of a lean condition. Get the JD Jetting kit.

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Yes I did, in fact I road the bike prior to the throttle change. It never faultured. I'm now told the throttle was replaced with one from an '06 model. But I wouldn't think that would be a problem. I'm wondering if the throttle cable\throttle position sensor could be out of adjustment causing the ignition timing to cause a problem. But then I would think it would spit and sputter. It just falls on it's face. :thumbsup:

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