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Super Moderator
2008 YZF-R125 (180cc)
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707 Posts
wow that sounds rough. seems like two potentially concering noises there, one with regular timing and one with irregular timing but with just 6 seconds of video idk.

It sounds like something's knocking around in there somewhere quite badly but if it was bottom end bearings (which would be among the worst outcomes), afaik that doesn't tend to get better at higher rpm. It might sound a bit smoother but you'll be able to feel that it's not happy. Also if it's that it will get noticeably worse over time to the point that it's very obviously that which is the problem.

Does it run ok generally? If it's losing top end that seems to be a fairly reliable indicator that something's amiss - so if its top speed is the same as usual it might be something secondary - e.g. something wobbly/loose in the stator or something rather than the "power-producing" elements (cylinder/piston/con-rod etc).

try holding your hand onto parts of the engine, you might be able to feel where the knocking sound is strongest and from that, knowing what's where in the engine might help diagnose it
 

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Super Moderator
2008 YZF-R125 (180cc)
Joined
·
707 Posts
right - so if it's runnign great then it's probably not bottom end related which would be worst case scenario. If you find it gets worse over coming weeks/months then that position may need reviewing. Tbh it sounded almost like something secondary rattling - so perhaps a loose bolt on something nearby.. idk, could be a dozen different things so speculatign is pointless but the one thing you don't want it to be is bottom end bearings cos that's a royal PITA to fix.

Sometimes just some time spent looking at it, and feeling around the area can sorta lead you to it, esecially if you can recreate the rattling at will.
 
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