Fzr 400 knocking noise

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faantjie62
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Fzr 400 knocking noise

Post by faantjie62 » Tue May 02, 2017 6:14 am

Knocking noise when on high revsImage

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faantjie62
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Re: Fzr 400 knocking noise

Post by faantjie62 » Tue May 02, 2017 6:21 am

Hi guys.i need some advice before moving to the next step.when bike is idling theres no noise but when reving the bike up to 8000 rpm it starts making a knocking noise but on top in the motor.though it was bearings but its not a screech sound.

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Evilchicken0
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Re: Fzr 400 knocking noise

Post by Evilchicken0 » Tue May 02, 2017 1:50 pm

Hmmm

So - it this a progressive noise, does it get louder as revs increase ?
Is it every bang of the engine or is every second bang .... ? If it's a camshaft related thing it will be at half time to the engine.
Could it be a misfire ? - at 8000 rpm youre going from idle to main jets so it could be this .... have a look on ebay and get a mechanics stethoscope put the end on the engine so you can hear whats going on inside. listen to each of the 4 cylinders through the block and on the exhaust so you have a better idea of where the sound is - Note I don't know how loud this is going to be so be careful. Listen to the cam cover

If you think its a misfire - look at the choke and make sure it's disengaging all the carbs, are the carb rubbers (where they join to the engine stubs) split or cracked ?? then check the airbox is on the carbs again check the rubbers and the see if the air filter is clean.

When did you last change the spark plugs ??? Have you worked on the bike recently ???

faantjie62
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Re: Fzr 400 knocking noise

Post by faantjie62 » Thu May 04, 2017 10:16 am

It gets louder when reving up.another guy from a bike shop told me its the crank thats worn out.and now the piston is touching the head.could this be true?

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Evilchicken0
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Re: Fzr 400 knocking noise

Post by Evilchicken0 » Thu May 04, 2017 3:16 pm

It could be ... to honest without hearing it or taking it apart I can't really tell.

If your engine was toast what would you want to do ? Cut your losses and buy another bike or look for a 600 engine for a transplant ???

Wraith
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Re: Fzr 400 knocking noise

Post by Wraith » Wed May 10, 2017 10:26 pm

Evilchicken0 wrote:get a mechanics stethoscope
Big Screwdriver.... :mrgreen:


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