Is it the clutch?

[CaPo]

Posting this for my brother, im pretty certain its the clutch but open to more experienced persons opinions:

So i think i might need a new clutch for my 98 gs500. Heres the symptons:

Bike starts fine and runs ok up to certain amount of revs (i dont know how much, no rev counter)
Once it gets to a certain amount of revs, in any gear, the bike just revs up without putting the power to the back wheel
I can feel the bike revving and turning over under me, but the back wheel doesnt move to compensate this
It happens in every gear
About 35mph in 3rd gear (roughly), if that helps

So im thinking perhaps the clutch is slipping. My spark plugs are fine, a nice shade of tanny/brown, spacing is good. Oil in bike is about 1mm under the full level. Type of oil is: Castrol GTX Magnatec 10W-40

Thanks for any help

[matthab]

Have a look and see how worn it is, as it does sound like its slipping. But its worth checking the chain etc!
____________________
2005 - 2006:Peugeot jet force 50 TDSI (sold)
2006 - Present: Yamaha YBR125 06 (extras:pilot sporty tyres and screen)

[hazza]

yeah that sounds like the clutch slipping to me
____________________
3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[dibs]

try flushing the oil out and replacing with an oil without friction modifiers as the purpose of the oil is to cool not lubricate the clutch plates the extra adhesion of the magnatech could be your problem.

[Kwaks]

Had the same problem myself,hence trying everything I could think of to solve without giving in to the theory of a fried clutch.

Two things I did which certainly made a difference to me (I was also having problems selecting gears) were to take off the left hand footrest assembly and give it a good clean and lubrication (the gear lever was too stiff and was stopping the returner in the cluch doing its job correctly) and also adjusted the tension on the cable (between the clutch and the lever connecting to the actual clutch cable).

These seem to have sorted my problems.my slip was noticable at only 10k revs.
____________________
Fallen Angel "Nae sniffing my seat now!!!!! "
www.cliqueycuntsmcc.co.uk
I AM NOT A FAST RIDER!!!!!!!!!

[CaPo]

Slip kicked in what seemed like a good bit earlier than 10k rpm on the quick shot I had of it.
So the plan just now is, re check the clutch cable to make sure its releasing fully. (Dont think its this as we already had a go tightening the adjuster on it and to me it feels like its biting at the correct position.)
Drain oil, remove clutch and measure the friction plates. Haynes says they should be 2.6mm minimum but they will probably get replaced if under 3mm.
If the thickness is fine get a proper bike oil, is it worth resoaking the plates in the different oil if this is the case?
Again, if thickness is ok then lubricate the gear lever assembly as mentioned above, this will probably get done anyway as it sounds easy and quick to do.

[dibs]

dont worry about buying a bike specific oil just make sure there are no friction modifiers eg magnatec in there. if normal mineral is good enough for you then castrol GTX can work out alot cheaper than castrol bike oil.

[Kwaks]

[R1stu]

Its most likely cooked!

My bike done the same! lack of oil in the gearbox.

Now it looks like this on the blanking plates! Might even have cooked the friction plates as well
____________________
Carbon closet tart! https://www.bikepics.com/members/r6stuk/02r6/
Stolen bike. 2000 R1: https://www.bikepics.com/members/r6stuk/00r1/
Current bike 1991 Honda ST1100 Pan European, 1986 Honda cb350sg (Finished)

[Pete.]

That steel don't look too bad from what I can see. If it's slipping but not turning the whole steel blue then I would suspect the oil as above. The proper thing to do is to either measure your clutch stack-height (all the steels and fibers stacked together) and check against the manual or measure each steel and fiber individually to check they are within wear-tolerance. If it's got very hot the steels can warp causing slip and/or judder.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[R1stu]

[Pete.]

If there was no oil in the gearbox then there was no oil in the engine and it would have seized had you run it.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[paulmuphesto]

hey this thread was started for my bike. i joined up to post some advances.

so i swapped the oil today. changed the old magnetec stuff for this: https://www.castrol.com/castrol/productdetailmin.do?categoryId=9003128&contentId=6008623

took the bike out for a spin and it seemed to be working perfect straight away (better than before with other oil actually). So the longer i had it out, the more i was revving it up high in lower gears to see if any slipping occurd. Seemed to be fine straight away, but after about 3-5 minutes i noticed it starting to slip again. Could it be that the friction plates etc will need time to soak in the new oil and get the magnatect stuff off of it? or perhaps the clutch is actually buggered. I tryed to get the side casing off to measure the plates but the thing was stuff on solid

also, when i took out the old oil : there was no metal fragments or anything similar, no smell of petrol, infact it didnt even look "that" used.

is it still ok the use the bike at low revs or will this cause the problem to get worse?

thanks in advance

[R1stu]

[Pete.]

The clutch isn't usually running in oil it's pumped-in via the pushrod tunnel. I don't know if it's true for your bike but it's the favourite method.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[paulmuphesto]

well if i take out the dipstick i can see the clutch under it, and it looks to be in the oil (bottom of it anyway)?

dunno if that matters tho....

is the bike ok to use tho or will it just make things worse?

[paulmuphesto]

so heres another update.

after leaving the bike with the new non-magnetic oil in it for well over 24 hours i took it out for a shot.

Again, starts up perfect, didnt even need choke. Very easy to select all gears (apart from neutral, but thats always been difficult). Bike starts off great, revs no probs, gets up to a high speed pretty fast, feels perfect actually. This lasts for anywhere between 3-7 minutes then uh oh.....the problem returns. oh and i couldnt get it above 60mph in 6th gear without the engine revving up without producing the power to the wheel

the clutch level is adjusted properlly, new oil in it just a fraction under full level.

you think its time to open up the clutch and starting measuring plates and what not?

[paulmuphesto]

so i took the clutch apart today. the plates were all just under 3mm but over 2.8mm. Ive ordered new ones anyways. Also the springs were about 10-15mm short of what they should have been.

Hopefully this is the problem and when i put in new springs and plates it will be sorted

[Pete.]

10-15mm short? I never heard of anyhting like that before.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[CaPo]

Its true, the haynes manual says they should be 60mm, we measured them all at about 48mm

[bish777]

GTX magnatech will cause the slipping-it has friction modifiers that cause the clutch plates to slip.

Try buying a can of the cheapest 20/50 motor oil and changing the oil for this. Take the bike out for a long run and check how the clutch performs. The cheap oil should hopefully help to clean out the magnatech.

Drain the oil and refill with summat more suitable-GTX high mileage works fine as it is compatible with wet clutches. Tesco/Asda 10/40 works fine, as does carlube 10/40, among others.

If you want to spend money on expensive oil, use a bike specific oil. Cheaper car oils are ok, but all the more expensive car oils contain clutch buggering modifiers.
____________________
GSXR1100J