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GSX-F400 Odd noise - Is this normal?

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Bravus, Aug 7, 2007.

  1. Been riding a Spada, just picked up a new (to me) 1988 GSX-F400 (import).



    Enjoyed the extra power a lot on the way home, even if an I4 takes some getting used to after a V-twin. All sounded good too, but there was an odd sound, kinda like 'something is coming unscrewed/bolted and spinning' on the over-run at low revs, particularly in top. Is this some normal sound (on opening my visor and listening closely it sounded more like an exhaust type thing than the unbolting)... or is something unbolting?

    (I know probably no-one else rides this specific bike but it's a GSXR engine so the sound would presumably not be unheard of - if it's normal.)
     
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  2. headers loose?
     
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  3. That's a possibility I guess - I'll check 'em. Sounded more like something rotating, like... I dunno, a loose nut on the end of the alternator or something...
     
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  4. i thought it was common for the top gear ie ; 6th mostly to be noisier as some have like a overdrive type function for cruising or its worn out so it makes a little bit more noise??

    both the bike iv had have had a noisier 6th gear
     
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  5. Bravus, i reckon it could just be the exhaust reverberating.

    I've heard some exhausts do it so badly (and strangely!) that I've searched for hours for the cause. Rev it in neutral at standstill and see if you can hear any signs of it.

    The engine bottom end is similar to a GSX-R400, but is more closely related overall to the GSF400 (Bandit) of 89.
     
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  6. How low is low revs?

    Just wondering if you need to recalibrate your brain to the I4 coming from a v-twin...
     
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  7. Yeah, I'm thinking and hoping that Cammo has it right - and certainly the 'sounding like it's revving twice as high' thing takes some getting used to. Will play around with it a bit on the stand today and see if I can duplicate it, but it's done 60 or 70 kays of all kinds of usage from buck forty overtaking to twisties and is still running sweet, so presumably it's nothing imminently engine-fatal.
     
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  8. Just having a close look now, the bottom edge of the radiator doesn't seem to be bolted tightly into place, it just sits in a couple of slots in its brackets. I wouldn't be at all surprised if what I'm hearing is a vibration of that at particular rev ranges. If that's the case it's not going to cause any trouble or go anywhere.
     
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