So i’ve never had any issues with my secondhand 07 ybr 125, until i came out sat morning and found the kickstarter out and a scratch on my tank. I think some stupid kid was screwing with my bike overnight. Three times during a short ride to clapham and back to streatham i was accelerating and i think the throttle jammed open and the bike revved high for a second. The rest of the ride it was fine, it seemed to be an intermittent thing. I dunno what’s happened to it?!
Any ideas as to what i should be looking at? The spring the throttle cable connects to seems to be working smoothly.
Twist the throttle open and shut very slowly to see if you can feel any slight snagging or resistance of the inner cable.
With the bike on the centre stand slowly turn the handlebars fully to the left and right checking for any snagging of the cable routing.
Take the twist grip apart and lubricate the inner cable and grease the cable ends - just for the fun of it.
Check the carburettor for any sticking parts and that its adjusted correctly. You may want some experienced help with this because there any many delicate parts in there that the slightest bit of grit, dirt or misplacement can result in havoc.
Intermittent faults are difficult enough to trace hands on, virtually impossible over the inter webby, they’ll be much trial and error.
Get it sorted as a priority, sticking throttle plus inexperienced pilot can only end in tears.
Thanks Martin and Art, i’ll have a look as best i can, i work for a company who have a fleet of keyholders with bikes so hopefully i can get their garage to have a free look for me. I am worried about, the more i think about it, i think all three times i was releasing the clutch, it happened taking off from lights twice, going into second gear and once into third gear and once going up a hill.
Your clutch maybe be getting stuck open, this happened to me once on my 125, scared the crap out of me because it was idling between 4-5k making my filtering home rather tricky when I was getting through some gaps.
When I got home, I did bit of research and it sounded like my clutch cable was sticking, so I started up my bike and then started fondling (for lack of a better term here) the clutch cable and I heard the revs starting to die, so kept at it until it idled between 1k-2k again. Never had the problem since.
Check for snagging around where the fork and frame meet
Add seafoam to tank to give carb a blast
Check oil isn’t black, if black change it
If it’s clutch slip you should feel it. You will feel the back go light as if it’s slipping out along with momentary loss of power to the back wheel which is very easy to feel when accelerating. Much more likely the throttle cable is sticky. My other 125 has a messed up clutch and you’d know for sure if it was that IME.
If I have one piece of advice it would be to buy the tool for oiling cables and use that, saves a lot of mess and oil.
