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Is this normal !!

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Hi guys, was wondering if it is normal for an 04 450 to pop when in nuetral and at about half to three quarters of throttle. Also it pops a fair bit on deceleration. did the obvious checks with a new plug, exhaust leak checks, fuel mixture settings. It was until recently used for supermotard racing and the engine recently had a complete rebuild. Nothing much is stock and it accelerates as it should so should I persist in trying to resolve the popping or put it down to one of the mods it has. cheers

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Yes it has a GYTR titanium exhaust and a bored out carby (don't know what the bored out carby is but just repeating what the previous owner told me) I can only guess that they have the correct jets for its mods as it was raced up until recently. Starts fine and pulls hard in any gear but won't high idle in neutral without popping as well as the decelleration pops. If it is normal I won't waste time or start annoying the mechanics, but if it is an indication that something isn't right I would like to sort it out . cheers

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If it accelerates good, it can't be a exhaust leak. Becuase you could tell an exhaust leak, with the loss of power.

:excuseme: That's pretty funny. But I don't think so. The two top causes of decel popping are a lean pilot and a leaking exhaust system. Typically, the leak will be at the mid pipe joint or where the header meets the head.

Neither of these things is really a matter of much concern, though, and popping on deceleration is fairly normal for an engine that's jetted correctly. On cooler days, or at lower elevations, it may do that, and on hotter days or at higher altitudes, it won't. You should have a pilot jet of a size that allows the fuel screw trim to deal with most of the decel pop. Ignore the rest of it.

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Thanks everyone for the advice. I will go over the bike again to check for an exhaust leak and then pull the carby apart for a clean and readjust the fuel mixture. It wasn't the decel popping that has me concerned but the popping when in nuetral at half idle/threequarters idle etc. The bike runs great other than that, so I didn't want to start looking for a problem that isn't any great worry. Not sure what fuel it was set up for, but going from whatever fuel they used to Shell Optimax might require a rejet job, or else my concern was it was a leaking valve or something like that. cheers and thanks

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Take a look at the throttle valve. It is a plate attached on the air filter side of the slide. They can crack and cause a lean mixture ratio on noticed on decelleration. It can break and let debris fly into head. This happened to me and caused a couple of bent valves.

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Thanks everyone for the advice. I will go over the bike again to check for an exhaust leak and then pull the carby apart for a clean and readjust the fuel mixture. It wasn't the decel popping that has me concerned but the popping when in nuetral at half idle/threequarters idle etc. The bike runs great other than that, so I didn't want to start looking for a problem that isn't any great worry. Not sure what fuel it was set up for, but going from whatever fuel they used to Shell Optimax might require a rejet job, or else my concern was it was a leaking valve or something like that. cheers and thanks

Do not use shell optimax!!!!

Use BP ultimate or mobil synergy 8000. Never Optimax. It fouls plugs.

Try switching fuels and your problem might go away!

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