NX250 odd engine (clutch?) rattle

[kuroguro]

Hello,

I have been worried about an odd rattle sound that has been getting louder in the last year I think . It can be heard while idling or sometimes when cruising at low (~4000) rpm. At first I thought it was the camchain or tensioner that everyone complains about but I discovered the sound goes away when I pull in the clutch.

https://youtu.be/yeIiBjobtK0

Some motorcycle models rattle from the factory in neutral but I think my NX was a lot more quiet before? Or is this normal? It is loud enough that I hear it in the middle of city traffic trough my helmet.

Any ideas what to check if it's not normal? I'm currently guessing it could be a worn clutch basket or maybe some gears nearby.

I know remote diagnostics from bad phone audio usually don't go anywhere just wanted to hear some thoughts.

[scrambler]

The NX250 engine noise always changes when the clutch is released, more so on some engines, less so on others. I couldn't find a cause for this in the engines I've disassembled. Theoretically, it could be the crankshaft bearings, but they were always fine. It's actually hard to tell from videos whether noises are normal, but I can't really hear anything suspicious here. I would keep driving and observe whether it really gets louder.

[kuroguro]

Ah. good to hear, I have been worried about this for a few months now. Maybe I just didn't notice it before. Will report back if it does get worse!

[kuroguro]

Update: what I thought was the same rattle were two different rattles! The one I can hear at ~4000 rpm was difficult to capture with phone audio and mostly appears while riding. Messing with the tensioner by turning it slightly counter clockwise the rattle disappeared.

After removing and inspecting the tensioner as best I could it seems to be functioning. Pressing it in fully extended I only have ~4mm left between the mounting surfaces. I assume this means my chain needs changing sometime (probably winter) but the tensioner is ok? Just doesn't work well near the end?

Btw how fast to the plastic chain guides wear down? Do you usually need to replace them with the chain or should I wait until I open the engine and check?

[scrambler]

Messing with the tensioner by turning it slightly counter clockwise the rattle disappeared.
I assume this means my chain needs changing sometime (probably winter) but the tensioner is ok? Just doesn't work well near the end?

I guess so. How many kilometers has the engine run? Is the timing still correct, or are the markings off? Then I would indeed replace the timing chain soon, because it has already stretched considerably. Otherwise, if the rattling isn't loud and doesn't get any stronger, you could continue driving for a while. Perhaps apply mass outs fix, if the rattling bothers you.

how fast to the plastic chain guides wear down? Do you usually need to replace them with the chain or should I wait until I open the engine and check?

I've never noticed any significant wear on the chain guides. On my NX250, they were still in good condition at 105,000km and have been reused, now with over 161,000km on the clock. I suspect they only wear out if the timing chain tensioner is manually over-tensioned or if there are installation errors. Here the chain guide was not mounted correctly and quickly worn out by the chain viewtopic.php?p=33915#p33915.

[kuroguro]

How many kilometers has the engine run? Is the timing still correct, or are the markings off?

I haven't taken the top off yet, I'll free some time for that shortly. The engine is currently at 86000km. The first owner had regular maintenance done by Honda up to 60000km - if they didn't change it by then... I think it might be the original chain from the factory still in there? I'm not sure if they can even last that long so probably not.

[scrambler]

The engine is currently at 86000km. The first owner had regular maintenance done by Honda up to 60000km - if they didn't change it by then... I think it might be the original chain from the factory still in there?

My magic crystal ball tells me it's still the original chain .

On my Nixie, the chain started rattling slightly at around 60,000km. At 97,700km, the rattling became suddenly so loud that I had to use massouts fix viewtopic.php?t=2534 . But only to complete the 100,000km run with the engine unopened. At 105,000 km, the timing chain was finally replaced. It was a DID chain back then, so it's done 56,000 km. It's already rattling slightly again.