Superbyke SBS125 'box sticking

[Phil007]

Hi,

new to the forum here and very pleased to find it!

I have recently bought a 57 plate SBS125 which i was riding on Sunday and noticed that sometimes when changing down the 'box seemed to get stuck, especially when coming down the gears. Later on i noticed that the clutch wasn't disengaging completely which i traced to a frayed cable which was down to about 2 strands! Just changed this and things seem generally fine after some adjustment but still seem to get stuck especially when coming down between 3rd and 2nd. Sometimes a "firm" foot does the trick but not always. Any ideas? Have i missed something when adjusting the cable or ...? It's a bit tiresome and possibly a little dangerous so any ideas would be appreciated.

Thanks

Phil

[forchetto]

Sounds as if the clutch is not freeing properly still. Your free play at the ball-end of the lever should be no more than 8-10 mm. I can't advise on the adjusting procedure at the engine end as I don't know that bike.

Here's a picture of one in case anyone recognises it:

[ZMC888]

Also check the gear shift, check that it is working properly, the arm could have been bent if the bike has been dropped at some point.

[Phil007]

Thanks for the replies guys. By freeplay do you mean amount of "loose wiggle" for want of a better description at the ball end of the lever or the amount of movement between full engaged and disengaged for the clutch.

Could it be oil level?

[ChinaV]

Hi Phil,

Try this:

Put your bike on the centerstand.

Turn the bike on and run it through the gears without using the hand lever to shift. Just move through the gears with the foot lever, (use your hand and not your foot). How difficult is it to shift compared to when you are riding on the road?

Next, turn the bike off and do the same thing. Does the bike go through all the gears easily or is it still difficult between third and second?

These tests might help us better understand if the problem is in the clutch, transmission, or might be a simple adjustment in the clutch cable.

Cheers!
ChinaV

[chinabiker]

I am not so familiar with all the C-Motos, have tried a couple of these though.

I don't know if the have synchronized transmission but on all the bikes I tried, I had to apply throttle blip when shifting gears down.

[Phil007]

Tried moving it through the gears as suggested by hand. When it changes correctly a definite motion can be felt along with a noise that indicates something happening correctly. However, it can still be felt to malfunction sometimes and when it does it's the same sensation as you would feel if the external linkage was sticking - which i've checked and can see no issues with. At the same time it feels as if the shifter isn't travelling through the same range of motion that it does when working correctly. This occurs whether the engine is on or off and also irrespective of clutch use. The problem seems also to occur randomly as far as which gear it happens with, also irrespective of whether going up or down the box. When it doesn't happen though the change is lovely!

I've topped the oil up no difference.

It's the apparently random occurrence that gets me! Could it be clutch still i wonder?

[forchetto]

Could it be clutch still i wonder?

If the clutch has been abused by lots of full-bore starts, dropping the clutch, etc the "castellations" in the clutch basket could be damaged and the plates wont slide properly within the basket.

Can you do "clutchless changes"?, you know, placing your foot on the change lever and when you do want the next up gear, release the throttle (just a tad to relieve torque on the cogs) quickly and at the same time flick the gear up into the next ratio. If it works OK like that, then it's the clutch.

[Phil007]

Hi again. Nope won't change either whether using clutch or not. Seems i can press as hard as i like on the shifter and it won't budge.

I've changed the oil now and for a while i thought it was sorted as it seemed to have stopped but after about 45 mins it came back again.

Bit of a pain as i bought the bike to practice on before my test! Do they test your ability to cope with mechanical malfunctions?