cbr125 forum

Hello everyone. So bike is running much better now after doing the springs and after the valve adjustment I lost my top end rattle! However there is still an insanely loud bottom end noise and I can't pinpoint what it is. The manual says bearings but it doesn't sound like bearings even though it's in the right area. I will post a video later to show you. It's very rythmic and sounds like it's coming from the clutch area. It also gets quieter when I pull in the clutch. No oil problems and oil is full and fresh. When changing the springs everything inside looked clean but that's just a quick judgement. Model in question is the 2007.

is it whining as when I pull my clutch it fades and if I move the bike abit forward with clutch out it goes and also sometimes my gear wont select first when stopped I either after rev or move abit forward lol

mine is 2008

I want to find out myself if its serious as if it is I be getting rid as I no spare money to spend a lot on repairs as I already spent loads doing parts to it

How many miles are on it?

I'm quite certain I know what the noise is, my bike used to do this until I put new bearings in it. I was never able to determine what specific bearings it was but when I pulled it down the majority of them were noisy. The noise would change considerably when the clutch was pulled in. My best guess would be mainshaft bearings as when you pull in the clutch you're putting a load on them and then the noise changes. It's very disconcerting when you hear it, and when you do, you tend to fixate on it

Bearing noise is fairly common on these bikes. It's kind of annoying as when they are new and quiet they are just as smooth as silk. So when they get a bit noisy it tends to really stand out.

When I pulled mine apart I used high quality Japanese bearings as replacements. Most of the bearings that were in it from the factory were the lower quality Japanese bearings made in Taiwan. There's two types, and the better ones are made in Japan

Either way, I know the noise you are talking about as mine used to do it. It's nothing to worry about, it's not going to leave you stuck and it won't come apart. But it is annoying. It's NOT the lifter plate bearing even though one might think it is. The tone change is caused by the load changing when you pull the clutch in which leads me to believe it's the mainshaft bearings.

Only way to fix it, which worked for me, was to pull the engine apart and replace all the bearings. When I did this there were very few bearings that were not noisy. This noise is very common on these bikes but you can ignore it

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

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

Almost 20k on it. Interesting. Definitely did not think this could be bearing noise! But yes very loud and annoying. Does the entire engine have to come apart?

Yup, that's about right (at least, the mileage when mine started doing it). The only way to get at them is to split the case which means engine re & re and then, since you're there, you replace them all The clutch assembly sits on the mainshaft - that's why it sounds like it's coming from there - because it is. But it won't be the clutch assembly, it will be mainshaft bearing wear. Probably increased tolerances and then when you pull the clutch in it alters the tone as it adds load to the mainshaft which in turn adds load to the mainshaft bearings.

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

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

If you got very loud noise get it sorted before it gives in

Mine got 21k and no loud noise just whining hope I dont get any loud noise as I bet it wont be cheap for a garage to fix

Best bet is get a few quotes from garages

Are they commin for bearings to go at that guys mileage as I use to have a scooter with 35k and still ran fine

It's not uncommon. But they will also keep running for a long time. I've been looking into using ceramic bearings but they are still very expensive.

_________________
Best & Thanks!
Marvin Miller
cbr125world Store

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