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Are these bikes just noisy?? New internals and still loud

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Just got my bike back together after going through just about the entire engine. Did the top end in May, bottom end failed shortly after so I had a very reputable builder split the cases and he did a new crank, almost all tranny gears, bearings, etc. Had a local shop do new ss valves, got it all back together and it still makes a racket! Obviously no rod knock etc, it was very obvious when the crank was going. The mechanic I had do my bottom end said the Kawi's are notorious for being loud, and honestly a lot of them I've heard have noticeable engine noise. Anyone else have a noisy kxf?

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I have a 2012 kx250f and if for whatever reason i ride without a helmet it sounds like my top end is going to blow but only under acceleration idling its a little loud but not bad.

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My valves make noise at idle and increase noise with throttle until exhaust noise overcomes it. Similar to their two stroke versions from ten years ago - KX is a audible motor. Didn't say noisy because I don't find it loud or irritating.

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One word.  YES.

Lots of cam chain and valve closing noise.  Though not excessively alarming.  You learn the ear difference between loud but smooth OR loud and something is wrong.  At idle you will definitely hear the engine upper valve train and chain over the exhaust.  Once you throttle up though, rip it!  

 

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PS:   the head cover and the head/cylinder compartment that houses the camchainway are made of quite thin metal as compared to other bike engines.  This thin material does not provide much sound deadening or dispersion.  So that is probably why they seem loud.  There isn't anything wrong.  It is just that there is only a thin membrane of pot aluminum metal away from being an "open" engine.  For chitzs and giggles, compare the thickness of buddy's cover or cylinder compared to your KX250f next time he/she has theirs apart.

Edited by FaceDeAce

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Hi,

I have a 2012 kxf250. It has just had a full top end rebuild, SS valves new guides and even new seats. Both before and after the rebuild there is a constant valve train noise from the bike. Kind of a 'whirring' noise I would say. I'm actually glad that I found this thread because at least I know it's just a noisy bike by design

Damien. 

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I just did a Kibblewhite SS intake  conversion on an 11 for one of my guys.

This was my first use of Kibblewhite conversion, and the kit I used had an inner and outer spring which seemed really stiff and overkill.

I called Kibblewhite to verify I had the correct parts which they assured me I did.

It seemed a to make a  lot of valve noise once I got it running  and I attributed it to the extra HD springs.

It was brought to me in pieces not running so I don't know what it sounded like before.

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I feel like all 4t motors are loud haha. my 15 has sounded the same since I bought it. noisy motors but I have about 42 hours and it runs perfect and the valves are still in speck

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