cbr125 forum

The other day I had the bike on the dyno doing a 6th gear run until the rev-limiter kicked in. On this particular run the dyno operator had forgotten to turn on the two large cooling fans that blast a ton of air over the rad. No big deal, as the accuracy of this test was not so important (I was looking for a general trend) but I did notice the bike getting hotter then normal....

Later on, doing some other testing, I thought I head a noise. At that point I pinned it down to the area of the cooling fan and was able to see it wobbling around in a half-hearted effort to cool the bike. I mean, it was cheezy and flopping like a fish!

Upon tear-down I found that that fan was no longer firmly attached to the shaft on the electric motor...

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Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...

As it turns out, the nylon lock-nut that holds it in place had gone south and because the fan sits in a cage it can't actually go south with the nut - hence the noise

The Honda OEM service manual actually states that the nut should be lock-tited in place and this makes sense. There is also a very tiny little keyway that the fan has to sit in. When you see just how thin the metal is on the fan it makes me think, ah Mitsuba, I'm no longer your biggest fan....

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...

But....at least Honda doesn't gouge us on the fan price....at $8.48 it was not unreasonable. This time, when I get some lock-tite, I will seal it in place so that this does not happen again

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...

YUP! Lock-tite is your friend!!

It sure is, that should be the end of that....

too bad the factory didn't use it when they installed it....

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...

Red is great stuff and trouble breaking free without heat. I think blue would have done the job just fine. But we all use what is on hand at the time. I will need to get in there and check the fan shaft nut.

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CVMG - Grand River Section
Moped Riders Association

Mopeds, scooters and motorcycles I play with, new and vintage.

I hear you. I actually borrowed some blue and put it on there but it was in the form of a 'chap stick' ? Ie. in a lipstick form (it was genuine locktite) but the thing is, I tried removing the nut after to see how well the blue 'stuck' and it wasn't very strong at all.

At that point I got off my cheap beep and bought some red. I knew the red would stick (from experience) and while being too 'stuck' could be an issue I figured the chances that I would need to take the fan off again, versus the high probabilty the nut would fall off again made me see red

Interestingly enough, Honda has tons of fans in stock and ZERO nuts. The nuts were back-ordered all the way to Japan...Because the fan is 'captured' and can't fall off this leads me to believe that the stock level on the 4mm nuts is empty for a reason....

From a manufacturers perspective nuts are tiny and dirt-cheap. So really, they should have tons in the system. Where did they all go?

I think your idea of checking yours is valid. My bike was new (700k) when I got it and there was no 'monkeying around' with respect to the fan. That nut backed off all on it's own.....

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...

Wonder why there wasn't a ny-lok nut used there? Will source one to put on when I have apart. Ny-lok/locktite.... not going to back off!

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CVMG - Grand River Section
Moped Riders Association

Mopeds, scooters and motorcycles I play with, new and vintage.

Apparently there was one from the factory. The service manual shows a nylon locknut for that application.

When I ordered in the fan I also ordered in a nylon locknut but the entire distribution channel was zero'ed - backordered all the way to Japan.

So I chose to use a conventional nut with a lock washer behind it. No-one had the proper sized lockwasher but this one worked OK.

So, OEM factory is supposed to be a nylon locknut. In retrospect, I have more faith in what I've done with the lock washer and red locktight I can't see it comping apart on it's own again

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

...because every day is MotoGP day when you own a CBR 125r...