Moped Riders Association

[the duck]

I'm really sorry to make my first post on this forum in such a fashion, but I desperaterly need help with my scooter.


I ride a Honda s-wing fes125-7 125cc.
A couple of weeks ago when I was picking up speed I felt a slight jerk forward and noticed a lack of power. the engine was still running with no warning lights on but it wasn't picking up any more speed, going up hill it lost speed until it settled at about 40mph.

Giving the bike a visual check to start off with I noticed that the rear brake pads were worn down unevenly, caused by the pistons being dirty (not much time for cleaning these days due to first child).

Saw that one of the pads was dragging on the disc.

Ordered new pads, cleaned calipers and put the new pads on. Made no difference to the bike, can get up to a max speed of 40mph on a flat instead of 70+mph.


Next I took off the crankcase to check the clutch, here was a problem, the nut that holds the clutch onto the driven face had come slightly loose and the clutch had hit the threads smashing part of the clutch and the threads on the driven face.

Replaced the clutch and the driven face.

No difference to the bikes performance.

Tried taking the air filter off incase it was clogged, again no difference to the bikes performance....

Replaced spark plug, no difference.

Took all of the covers off and checked the engine, can't see anything leaking, the engine idles fine, sounds fine, and when it's on the centre stand with the back wheel in the air, the engine with rev up to the limit and the speedometer will show 70+mph. No funny noises or stuttering.

Took the clutch apart and checked it again, nothing wrong there, bike still not performing.

My dad suggested that the belt might be slipping under load, or that the belt might had stretched slightly when I felt the initial jerk forward.

Ordered a new belt and rollers (just for the sake of it). These parts have come today, my dad has fitted them while I've been at work and he says there is still no difference to the bikes performance.

I'm going to check the transmission on the back wheel tonight, to see if any of the gearing there has broken, apart from that I've just not got a clue as to what could be wrong with the bike.
Can anyone suggest anything else to check?

[maddog]

check your weights for flat spots also on the ramp replace the 3 plastic ramp guides as they wear it will slow your top speed. also clean the belt dust out of the trans case & cover with an old tooth brush...

[the duck]

[maddog]

one other item to check would be the rear pulley drive, behind the clutch there will be 2 or 3 pins that ride an S groove that open and close the pulley if its not greased the pins will bind causing the loss of power, after you take the clutch off if you see any bumps on the collar = the unit is shot and must be replaced.

[the duck]

Checked the collar, it's showing no signs of distress.

Checked the engine compression and it is low, so I'm trying to rebuild the top of the engine at the minute.

[the duck]

Turned out to be a pipe inside the exhaust had broken and the exhuast was bogging down the engine.