down on power....
Discussion
ive got a lil yamaha sr125 (1992) for commuting. bought it in nov and been doing little jobs here and there to keep it on the road.
there's 1 issue that i cant seem to figure out... i think the clutch isnt fully releasing and therefore slipping.
it has, on occasion, when ive messed with the clutch cable (lever end) sorted it and then hit 65 with better acceleration. however when ive gone back to the back its the same again.
the clutch cable where it connects to the arm (engine side) wasnt connected correctly. the cable sheath has a threaded part with 2 nuts that fit over each side of a clamp (thingy) to hold it in place. (you can kinda see the clamp bit towards the far middle of the engine on the below pic - i apologise for the s
tty pics im in work atm and they will only let you on certain sites).
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/FfoAAOSwP...
well the nuts were on one side of the clamp (right hand side furthest away from arm) effectively lenthening the cable. so i assumed it was the wrong cable and bought another.
i put the new cable on and clamped it correctly (followed the haynes manual - lined the arm up with a noth on the engine case). started the bike and put it in gear it jumped forward and cut out. so as if i didnt have the clutch lever in. so had to clamp it exactly the same as it already was.
but its still the same issue. other symptoms:
- anything above 3rd gear is useless (there isnt a rev counter but i think its because the revs are to low)
- i can actually sometimes feel it slipping... where you will accelerate, nothing happens then after a few seconds it starts accelerating.
Im stumped. cant think what to do. maybe, if possible, move the arm (thingy) round or replace the spring on it (see pic)
https://www.motorcyclespareparts.eu/App_Themes/VDM...
Any help is appreciated and apologies if its waffly im trying to explain it and work at the same time and i cant multi task.
Cheers
Pete
there's 1 issue that i cant seem to figure out... i think the clutch isnt fully releasing and therefore slipping.
it has, on occasion, when ive messed with the clutch cable (lever end) sorted it and then hit 65 with better acceleration. however when ive gone back to the back its the same again.
the clutch cable where it connects to the arm (engine side) wasnt connected correctly. the cable sheath has a threaded part with 2 nuts that fit over each side of a clamp (thingy) to hold it in place. (you can kinda see the clamp bit towards the far middle of the engine on the below pic - i apologise for the s
tty pics im in work atm and they will only let you on certain sites).http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/FfoAAOSwP...
well the nuts were on one side of the clamp (right hand side furthest away from arm) effectively lenthening the cable. so i assumed it was the wrong cable and bought another.
i put the new cable on and clamped it correctly (followed the haynes manual - lined the arm up with a noth on the engine case). started the bike and put it in gear it jumped forward and cut out. so as if i didnt have the clutch lever in. so had to clamp it exactly the same as it already was.
but its still the same issue. other symptoms:
- anything above 3rd gear is useless (there isnt a rev counter but i think its because the revs are to low)
- i can actually sometimes feel it slipping... where you will accelerate, nothing happens then after a few seconds it starts accelerating.
Im stumped. cant think what to do. maybe, if possible, move the arm (thingy) round or replace the spring on it (see pic)
https://www.motorcyclespareparts.eu/App_Themes/VDM...
Any help is appreciated and apologies if its waffly im trying to explain it and work at the same time and i cant multi task.
Cheers
Pete
If you are certain the cable length, adjustment, levers are all correct, there's only really the clutch left. It sounds like that's the cause to me.
You can actually measure the thickness of each friction plate if you lack faith in your diagnosis with a Vernier caliper. But given they cost a balloon and a ha'penny to replace and its a consumable, I'd just crack on with changing them. Also check the springs are in tolerance, and re-use the steel plates if they're not warped.
It's a piece of piss job.
You can actually measure the thickness of each friction plate if you lack faith in your diagnosis with a Vernier caliper. But given they cost a balloon and a ha'penny to replace and its a consumable, I'd just crack on with changing them. Also check the springs are in tolerance, and re-use the steel plates if they're not warped.
It's a piece of piss job.
Prof Prolapse said:
If you are certain the cable length, adjustment, levers are all correct, there's only really the clutch left. It sounds like that's the cause to me.
You can actually measure the thickness of each friction plate if you lack faith in your diagnosis with a Vernier caliper. But given they cost a balloon and a ha'penny to replace and its a consumable, I'd just crack on with changing them. Also check the springs are in tolerance, and re-use the steel plates if they're not warped.
It's a piece of piss job.
maybe for you but as you can tell from my diagnosis im not very mechanically inclined. but cheers lads i'll have a read up about replacing the plates and springs and see where i go from there.You can actually measure the thickness of each friction plate if you lack faith in your diagnosis with a Vernier caliper. But given they cost a balloon and a ha'penny to replace and its a consumable, I'd just crack on with changing them. Also check the springs are in tolerance, and re-use the steel plates if they're not warped.
It's a piece of piss job.
)? it felt to me like i managed to get the revs up to a certain point before i changed gear and then it picked up more speed.You don't mention it in your opening post, but do you definitely have some free play in the clutch lever? i.e. is the first 10-15mm of travel very easy, and then the lever stiffens up as the clutch is released? If not, adjust the cable until you get the required free-play.
If it still slips:
The clutch operating arm on the crankcase (the part the cable attaches to) has a point (i.e. arrow head shape) formed on the end, and this should line up with a dot on the crankcase when all the free play is taken up. To check this, disconnect the cable, and push the arm with your fingers in the normal direction of operation until it stops. At this point the arrow and dot should be aligned.
If they are aligned, or very close to, and the cable is adjusted properly, then it's time for new plates. If the arm stops well before the dots are aligned, then the pushrod clearance is too tight and needs to be adjusted.
Unfortunately on the SR125 the pushrod adjuster is mounted on the clutch pressure plate, so you'll have to remove the clutch cover. You'll probably need to either drain the oil or lean the bike over against a wall etc. to prevent a tidal wave of oil when the cover is removed. Loosen the lock nut in the middle of the clutch, turn the centre adjuster whilst pushing the operating arm until the point and the dot are aligned. Then tighten the lock nut.
Since the clutch plates are pretty cheap, if you need to adjust the pushrod clearance you might as well do the clutch plates at the same time. Note that you must set up the pushrod clearance as above when new plates are fitted.
SR125 service manual in case you don't already have it.
The clutch cover is probably held on by what appear to be Philips head bolts. In fact they probably a special Japanese fitting that is similar, but not quite the same as a Philips head. These screws may well be quite tight, so a basic impact driver is a good investment if you don't have one.
If it still slips:
The clutch operating arm on the crankcase (the part the cable attaches to) has a point (i.e. arrow head shape) formed on the end, and this should line up with a dot on the crankcase when all the free play is taken up. To check this, disconnect the cable, and push the arm with your fingers in the normal direction of operation until it stops. At this point the arrow and dot should be aligned.
If they are aligned, or very close to, and the cable is adjusted properly, then it's time for new plates. If the arm stops well before the dots are aligned, then the pushrod clearance is too tight and needs to be adjusted.
Unfortunately on the SR125 the pushrod adjuster is mounted on the clutch pressure plate, so you'll have to remove the clutch cover. You'll probably need to either drain the oil or lean the bike over against a wall etc. to prevent a tidal wave of oil when the cover is removed. Loosen the lock nut in the middle of the clutch, turn the centre adjuster whilst pushing the operating arm until the point and the dot are aligned. Then tighten the lock nut.
Since the clutch plates are pretty cheap, if you need to adjust the pushrod clearance you might as well do the clutch plates at the same time. Note that you must set up the pushrod clearance as above when new plates are fitted.
SR125 service manual in case you don't already have it.
The clutch cover is probably held on by what appear to be Philips head bolts. In fact they probably a special Japanese fitting that is similar, but not quite the same as a Philips head. These screws may well be quite tight, so a basic impact driver is a good investment if you don't have one.
Edited by Mr2Mike on Tuesday 21st April 17:21
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