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YBR125 Clutch/Gearbox Problems


nexusnode
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Hi all, thanks for reading.

Am hoping someone on here might know a bit more about clutches and gearboxes than me and be able to tell me whether my guesses are right or not.

I think I have two seperate problems but they might be connected...

First one is about false neutrals. Reasonably often my bike doesn't like going from 1st to 2nd and just goes into neutral, not quite so often it does the same thing going from 3rd to 4th. It tends to happen when I am accelerating (relatively - its a 125 so not really) quickly. At first I thought it was just me being rubbish and not making a strong enough change action but I don't think thats the case any more.

I commute to work and back along a strip of 50mph road, the last few days that I have been out whilst going along here in top not accelerating the engine has for about a second or two started revving like it either wasn't in gear or like the clutch hadn't engaged. But then after a second or so - without doing anything it sorts itself out.

Thanks!

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  • Moderator

This has been posted time and again about this model. All I can say is do a search and read about previous posts.

I would recommend an oil change and use the correct spec oil, not something too high a viscocity, also check the level is not too high. And be firm with the foot change.

Also keep a check that the lever does not come loose on the splines because next thing is they will be rounded off and then off the road. ;)

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This has been posted time and again about this model. All I can say is do a search and read about previous posts.

I would recommend an oil change and use the correct spec oil, not something too high a viscocity, also check the level is not too high. And be firm with the foot change.

Also keep a check that the lever does not come loose on the splines because next thing is they will be rounded off and then off the road. ;)

Thanks for your tips I will give them a try.

I would like to point out though that I did search your forum first and found nothing. The only posts related to this model when doing the search "ybr125 gearbox" is one that is about a fuel cock and a second that is about lost keys... I might be new to this forum, but it does not mean I am ignorant of forum etiquette.

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Once again, thanks for the link. Apologies, I assumed that because you are a moderator that you would have some say about the performance of this website and its forum.

If I am honest though, the false neutrals whilst a pain in the bum - I can live with so long as I don't think they are causing damage. The bit that is concerning me more is this bit:

I commute to work and back along a strip of 50mph road, the last few days that I have been out whilst going along here in top not accelerating the engine has for about a second or two started revving like it either wasn't in gear or like the clutch hadn't engaged. But then after a second or so - without doing anything it sorts itself out.

After reading all of those threads , none of them appear to have anything like this in them. Any ideas? Thanks in advance

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  • Moderator

Classic signs that you need new friction plates in your clutch, this is always shown up in top gear when the engine is working hard.

I assume there is a little play in the cable is there?

Oil...Its not over full is it?

Sprockets and chain tension...All good?

If it is a clutch strip you may as well replace the springs too.

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Classic signs that you need new friction plates in your clutch, this is always shown up in top gear when the engine is working hard.

I assume there is a little play in the cable is there?

Oil...Its not over full is it?

Sprockets and chain tension...All good?

If it is a clutch strip you may as well replace the springs too.

sounds like good advice, I will get those all looked into as soon as I can and let you know. Thanks again!

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  • 3 months later...

I had a look at all the bits mentioned above but none of them solved my issue. I have solved some of the problem though and thought I would post on here to let you all know what I did.

I found that the gear shift shaft was floating a lot inside the engine casing and when at one extreme it was rubbing against the back of the clutch housing. This had the effect of making changing gear problematic which produced the false neutrals...

Now I have a copy of the official service manual and I can't find any mention of anything that restricts the shafts float. (Please correct me if you know any different)

I ended up making a spacer between the shift lever and engine case to force the shaft into a good position. I also put a washer on either side of the spacer to make sure it doesn't cause any damage.

It has since made my gear changes very smooth.

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  • 1 year later...

This seems to be a common issue in all yamaha ybr 125s even the custom bikes have the issue of Gear change 1st to 2nd and both me and my ossicate have both had accidents due to this issue he took his bike in for a service and it turns out there is a fault in all thease ybrs his gearbox is now being changed and im hoping to get my changed in my service next week as i keep bringing this issue up and have been told excuses like its a new bike it cud be the oil m nt strong enough where the issue keeps accouring also ive had the issue of being stuck in neutral and nt being able to get into first i will keep the updates coming on what happens in my service

Hope this helps

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