Gear problem on honda cg 125

[emprex]

Hi

Since this morning It is impossible to pass the first gear, the motorbike starts but it's impossible to ride, when I release the clutch the engine doesn't get off... when I push a bit the motorbike i can hear some clac, clac in the carter. I changed my oil two days ago and everything seemed to be ok. Any idea?

Guillaume

[Adam]

Did you put the right oil in? Did you do the sump plug up properly? I assume the problem has started since the oil change so I'd be inclined to check it first and maybe even change the oil again. Other things to check would be the chain tension and clutch free play.

[emprex]

Hi Adam,

thanks for your answer. For the oil I put 750 ml of shell Advance AX7 4T 10W-40. I hope it's the right one... I will check the chain tension and the clutch today, and as I did some settings on the carbu, the problem might come from that as well?

Guillaume.

[Tango]

750 ml......that don't sound like much oil....check the sight glass or dipstick to make sure the level is OK....

[emprex]

Hi,

I do not have at all free space on the clutch, that might be the problem as I can turn the back wheel when I release the clutch, going to try that. For the oil I have to put apparently 1L. going to do that as well. Will let you know soon. I bought this motorbike two months ago and the guy told me everything is done, all you have to do is to ride... that is my first lesson!

many thanks, .

Guillaume.

[emprex]

hi

Well I guess I do have y answer... I've opened the left carter to see what going on and I've discovered a lots of iron filings on the chain and in the carter... the small pinion of transmission is dead. I have to change it.

Thanks for all your answers and I hope it's the only thing I have to change...

Guillaume

[emprex]

Correction: we don't call that a small pinion of transmission but a Front Sprocket apparently. sorry for the mistake...

Guillaume

[Tango]

No probs Guillaume.....your English is a darn site better than my French.....

Given that the front sprocket is broken, I think I would replace both sprockets and the chain if that were me....

[emprex]

Thanks tango

I have ordered the full kit chain and the a new front sprocket retainer as well as it is totally slick inside. I wonder what is the cause of that?

Guillaume

[Adam]

I second that definitely get a brand new chain and sprocket set they will last much longer if they're all new.

[Fozzie]

Looks like it got caught or wasn't seated properly... I wonder why that happened.

When you piece it back together, show us a picture with the new sprocket fitted.

Should be able to see what the issue is then if there is one!

[emprex]

Hi Fozzie,

Will do it yes,but now I have to wait 3 days to get the new pieces.... Drives me mad as I would like to ride a bit! I bought it to learn I am served haha

thanks,

Guillaume

[emprex]

Hi,

Can the chain tension be involved in that problem, I've less than 1cm of movement?

thanks,

Guillaume

[Adam]

Yes, generally we say about an inch (2.5cm) at the slackest point of the chain. Check your bike manual for the exact free play.

Have you adjusted your clutch at all? As this can also affect it.

[emprex]

Hi,

so I did a series of pictures in order to show you what is the situation.

I that situation it seems the sprocket is free to move on the axis. Is that normal?

If not what do I miss? I've remove 1 front sprocket retainer( witch is totally slick inside), 1 front sprocket, and 2 screws.

thanks for you help

Guillaume

the initial position of the chain.

do I miss something?

Is that ok? (transmission axis...)

the max position I can go.

[Mr Fro]

The pics are a bit fuzzy but it looks like the sprocket and output shaft are badly worn.

Does the sprocket spin on the shaft?

[emprex]

hi Mr Fro,

When the sprocket in on the max position no, but when it is at the initial position it does spin on shaft...

[emprex]

it's worth it to replace the output shaft? http://www.ebay.co.uk/itm/HONDA-CG-125-97-GEAR-BOX-INPUT-AND-OUTPUT-SHAFTS-GOOD-CONDITION-/191139554613?pt=UK_Motorcycle_Parts&hash=item2c80ce2535 with that maybe?

[eastanglianbiker]

you can only replace the output shaft by doing a complete dismantle of the engine including removing the cylinder head and barrel due to how the main engine cases come apart on that engine so unless you konw what you are doing and got decent tools it will be a big job and dont forget you would also need full gasket set for the rebuild as well

[emprex]

Hi,

thanks a lot for all your answers, and your help. I release a bit the clutch and the chain tension. I replace the sprocket and the retainer. It seems to be fine for now. Don't know for how long...

Guillaume.