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‘11 KTM 350 SXF whirring / whine noise after full rebuild

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I just had my KTM bottom + top end rebuilt. 
Prior to splitting the cases it had a horrible supercharger / whine noise that was in sync with the RPM and it was painfully loud. 
 

Now that the engine is completed and should be in perfect running order I can still hear a whine that is in sync with the RPM but it’s no where near as loud compared to before... but it still worries me a lot because I just spent over $1500 on it

Video of issue: 

 

 

 

(The top end rattle is due to having the MCCT too loose and isn’t a concern. The cam chain is not the problem)

Any help or suggestions will be highly appreciated! Thanks

Edited by Christopher Hurlimann
Added video

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To me the (whirring noise) sounds like the cam chain rubbing on the guides, or I know in the past, that you can make that noise by tightening down the cam chain.

I don't hear any rattle from a loose mcct, are you sure its not too tight.

 

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On 9/27/2019 at 9:23 PM, Spud786 said:

To me the (whirring noise) sounds like the cam chain rubbing on the guides, or I know in the past, that you can make that noise by tightening down the cam chain.

I don't hear any rattle from a loose mcct, are you sure its not too tight.

 

Been busy with life lately, sorry for the late reply!

 

It isn’t the cam chain, I ran the engine with a loose cam chain and it still makes the exact same noise ? 

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Do yourself a favour and stethoscope your motor, use the screwdriver method as talked about in this video (~1 min mark) .  Then once you've got a better idea of the location of the noise, you can easily eliminate possible causes.

 

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On 10/9/2019 at 5:14 PM, zibbit u2 said:

Do yourself a favour and stethoscope your motor, use the screwdriver method as talked about in this video (~1 min mark) .  Then once you've got a better idea of the location of the noise, you can easily eliminate possible causes.

 

Thanks mate did this and the noise was coming from right behind the waterpump. Found the waterpump bearing was knackered.

Replaced the waterpump bearing and it still makes the whine noise...

Any idea on what it might be? Surely it wouldn't be from having straight cut gears on the primary gear and clutch basket?

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5 hours ago, Christopher Hurlimann said:

Thanks mate did this and the noise was coming from right behind the waterpump. Found the waterpump bearing was knackered.

Replaced the waterpump bearing and it still makes the whine noise...

Any idea on what it might be? Surely it wouldn't be from having straight cut gears on the primary gear and clutch basket?

If I'm not mistaken all bikes have straight cut gears between the primary and clutch basket.. Normally they don't whine like that.

I think your next step is to go deeper in the water pump area and start looking at other bearings and/or the timing chain guides.  The balancer shaft (water pump shaft)  has two bearings supporting it.  The furthest outward is a ball bearing (chances are you replaced that one), and further inboard behind the timing chain is a needle bearing.

If those aren't the culprit, I'll keep my fingers crossed for you that the crank bearing is still happy.

Strictly by chance, but do you still have the factory header that you can install on the bike?  For curiosity sake, I'd like to eliminate the possibility that the noise isn't caused from the thin metal on the FMF Megabomb.

Good luck-

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On 10/25/2019 at 7:22 PM, zibbit u2 said:

If I'm not mistaken all bikes have straight cut gears between the primary and clutch basket.. Normally they don't whine like that.

I think your next step is to go deeper in the water pump area and start looking at other bearings and/or the timing chain guides.  The balancer shaft (water pump shaft)  has two bearings supporting it.  The furthest outward is a ball bearing (chances are you replaced that one), and further inboard behind the timing chain is a needle bearing.

If those aren't the culprit, I'll keep my fingers crossed for you that the crank bearing is still happy.

Strictly by chance, but do you still have the factory header that you can install on the bike?  For curiosity sake, I'd like to eliminate the possibility that the noise isn't caused from the thin metal on the FMF Megabomb.

Good luck-

Already onto it mate!

Pulled the balancer shaft and checked the needle bearing, it didn’t feel too bad but I’m already balls deep into it so I’m replacing it anyway 👍

I’m also replacing the wear bushing on the Waterpump shaft because I believe that the waterpump bearing behind the impeller seized and wore it out prematurely.

I do not have the stock header but I can run it without an exhaust and see what happens? 

Thanks for the help mate! I’ll let you know how it goes!

Edited by Christopher Hurlimann
Added more text.

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Ended up replacing the needle roller bearing behind the Balance shaft and the wear bushing on the WP

Didn’t make any difference at all.. it still makes the exact same noise.

Took it for a 20 minute ride and it rides flawlessly, couldn’t fault it! Just going to keep riding and see what happens.. got a big 3 day riding weekend coming up so I guess that will either make or break this &%$#@! of a bike lol

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