CRF450x Engine Knocking sound

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blauth

Race Dog
Joined
Oct 13, 2008
Messages
3,031
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Location
Johannesburg
Bike
AJS (all models)
Hello Lads,

I've just bought a CRF450x 2010 model. Original rear tyre (albeit smooth) still but somewhat poorly maintained. The bike hasn't been ridden hard.

I didn't notice a knocking sound when I test rode the bike but I can't honestly say I tried particularly hard to listen for one.

So as soon as I got it home, I lubed chains, oiled airfilter that was bone dry and did oil change on gearbox (750ml) and clutch (750ml - slightly more than recommended as per various recommendations).

Then I started her up and there is a very distinct knocking in the engine. It appears to be when the engine isn't under load. I took it to a mate who races MX and run an MX team and we pulled the tapped cover off. It looks new up there. Decompression mechanism is fine, timing chain is fine, valve clearances are correct.

There are no filings in the oil.

So I decided to ride it either way (all or nothing attitude) and she got hammered at the MX track for about four 18 laps. It pulled well with no hickups but the knock is still there and still worrying me.

Any suggestions as to where to start looking?
Please don't everyone jump to the preverbial 'Big End is gone' conclusion. The knock quietens down when under load or revving her up.

Thanks
Barry
 
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