View Full Version : Rs125 died mid ride help pls!

12-30-2015, 08:42 AM
I have a problem with my aprilia rs125 2008 and am wondering if anyone could help.

Last night i took my bike out, warmed it up and took it easy for the first 10 mins or so. After about 25 mins i started to head back home, half way there i stopped at a mini roundabout to give way. When i pulled away and went over the roundabout i pulled in the clutch and switched to second gear. As i let the clutch out and pulled back the throttle the engine suddenly died followed by a kind of low pitched twang noise, (not sure but this might of been the engine slowing down).

I rolled to the side of the road and switched into neutral. Then i tried to start the bike, the starter was working but it sounded different as if it wasnt engaging the engine. I had a new spark plug on me so i put that in tested for a spark and all was fine. When i put spark plug in and tried to start the bike it had made no difference. Halfway pushing it home i decided to see if it would bump start. Pulled in clutch put it in second and started pushing, however it was as if i hadnt pulled in the clutch and i could hear the engine turning but not firing. Im not sure if the problem is the piston but then the bump start thing leads me to think its the clutch, im absolutely baffled.

Can you tell me what you think is wrong.

Also when in gear and trying to electric start the bike lunges even with clutch pulled in.


12-31-2015, 03:07 AM
Sorry to hear about your problems, I assume it didn't start when you tried to bump start it? What does the clutch feel like when you pull the leaver in has the feel changed? That noise you heard could it have been the throttle cable snapping have you looked a the carb to see if it is operating ok? A broken throttle cable and a hot engine maybe why it wouldn't start. Have you tried to start it since? With a cold engine and the choke on it should still start with a broken throttle cable.

01-01-2016, 01:24 PM
No clutch lever doesnt feel different, throttle cable is ok, im getting a spark,piston is moving with starter button pressed in, i can get it into 1st 2nd and neutral have litteraly checked everythimg apart from inside where the clutch is. When i tried to bump start the piston was moving even with clutch pulled in but still wouldnt start. Im thinking it might be that the clutch is somehow jammed or a problem with the bottom end. Im guna try get the clutch side off tomorrow and have a look. As for checking carb, im not really sure what im doing in that area but i pressed the ignition whilst i had spark plug out and there was a verry strong smell of petrol so im asuming its ok.
Thanks for the reply

Also yer tried a couple times to start it but the starter just sounds different

L.T.R 250
01-01-2016, 01:38 PM
could of grabbed a ring, do you have a compression tester?

01-01-2016, 01:47 PM
No litteraly only been riding 3 months and this is the first problem. Would a pinched ring stop it from firing at all and would it also make the engine still crank with clutch pulled in whilst pushing it in gear?

L.T.R 250
01-01-2016, 03:04 PM
yes can stop it from running, can't see a reason y it would cause the other fault

01-01-2016, 03:28 PM
Me neither every solution i come up with is contradicted by somthing else, tomorrow im guna take off clutch cover and have a look and if its not that i will strip top end and check piston rings like you said. Il update as soon as you iv done it. Thanks

01-05-2016, 01:24 PM
Havent had time untill now but i bought a compression tester and tried it straight after work today and it barely gives me 1psi. Looks like im guma have to take piston out and see what the damege is. Theres just 1 question i have though, what is the best way to bleed and disconnect the radiator?

L.T.R 250
01-05-2016, 04:47 PM
Said it would be top end,

I just remove bottom rad pipe which fits to rad, can take the drain bolt out which is on the left side around the clutch case at front, but i just do as 1st said.

02-08-2016, 04:03 PM
Just a quick update
piston, barrel and rings were mangled! Sent barrel to be resleeved and ordered gaskets, vertex piston + rings + gudgeon pin and small end bearing. Fitted all these and bike started first time and rums well but i have one concern, there is a kind of whistling/whining noise that i THINK is coming from the top end somwhere. The noise speeds up and slows as per the piston speed.

Iv read a couple people have had this noise occur but dont know if it happened after installing new parts. Anyway they seemed to have fixed it after replacing balance shaft gears.

so my questin is, does this sound like the problem i am having or is it just the new parts breaking in?

any ideas would be appreciated