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

Bike starts fine and runs ok upto 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: http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_254023_langId_-1_CarSelectorCatalogId__CarSelectorGroupId__varient__categoryId_77303_crumb_33958-53252-77302_parentcategoryrn_77303

Thanks for any help

You should try to adjust your clutch cable (under the rubber cover where the clutch lever pivots).  If the cable is too "short", then it may not be full engaging when you release the lever.  I had similar symptoms and a cable adjustment was all I needed.

If you have to change the clutch, I would go aftermarket. Buy a kit with the friction plates, steel plates and springs and the gasket off course.

To make sure it's the clutch, you can measure the thickness of the plates to check if there're still in spec.

Another less accurate but easy test is to run the bike with engine at operating temperature, drive e.g. 30 mph in 2nd, shift the 4th, and with the clutch pulled in, rev too 7000 or more rpm and then let the clutch go very fast while still applying lot's of throttle.

If the revs don't drop to let's say 2000 - 3000 rpm but stay above 5000 rpm, you're clutch is slipping.

Another possibility could be that there's a problem with the vacuum slider in the carbs, or, as mentioned, the clutch cable. You might want to check those too.

just had this bit of advice from another forum

"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."

Does anyone here think this may have something to do with it?

Thanks

Quote from: Paulmuphesto on April 28, 2007, 02:51:43 PM
just had this bit of advice from another forum

"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."

Does anyone here think this may have something to do with it?

Thanks

I have no experience with the car oil you're using. I always use motorcycle oil. Is it the first time you're using it? Did you have the probs right after changing to this new oil?

Quote from: Paulmuphesto on April 27, 2007, 12:50:21 AM
....
Type of oil is: http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_254023_langId_-1_CarSelectorCatalogId__CarSelectorGroupId__varient__categoryId_77303_crumb_33958-53252-77302_parentcategoryrn_77303
....

Looks like you are using a synthetic oil. Not the first time a stock cork clutch has slipped using syn. Go back to conventional dyno oil.

I always run the cheap dino crap.  Motorcycle specific is just a ploy to rip you off.  All you have to do is read the side of the bottle and make sure it's the right rating.  I learned my lesson long ago about running synthetic.  I have a 67 yamaha and made the mistake of running partial synthetic once and the clutch was absolutely horrific.

Jake

"Magnatec 10W-40 and 15W-40 are both part synthetic. All grades of Magnatec contain Intelligent Molecules for active and continuous protection. "

i was under the impression semi-synthetic was ok to use?

however, from the offical castrol website

"Can I use Castrol Magnatec in my Motorcycle?
We would not recommend using Magnatec in your bike. Castrol have a specialised range of Motorcycle oils engineered with Trizone TechnologyTM for ultimate protection for all critical zones of your bike, engine, gearbox and clutch. "

i guess its oil changing time then, may aswell put this stuff into the car well im at it 

u can also buy a bottle of Lucus oil additive and put a cap full per oil change

Lucas makes awesome shaZam!   I use their additive too   Says 10% for wet clutch so yeah about a capful or so

G7

Quote from: spcterry on April 29, 2007, 03:21:12 PM
Lucas makes awesome shaZam!   I use their additive too  

YOU are no longer a grasshopper


All seriousness tho yea it's not the synthetic part of the oil, it's the additives. Off the top of my head the Quaker State 4x4 brand has the bad additives and I think the mobil clean 7500 brand does too....I"m sold on Castro 10-40 tho Auto-Zone had a special on a case pack...picked me up 4 cases for my fleet

so i swapped the oil today.  changed the old magnetec stuff for this: http://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

hello, i have run motorcycle spesfic syntethic oil in my gs with good results... smother shifts and much smoother power shifts... but at 40 cdn for 4 liters... i have swiched back to partsource castrol mc oil (non synthic) 3.95 1 liter...

before even changin the oil i would have adjusted the clutch cable.... there is a great video that Kerry made in the how-to section...

if it is slipping after it is warmed up... dunno......  but what i do know that there is a search function..... someone has had to have this problem before..

but before that; ADJUST THE CLUTCH CABLE... i do it once a year.... im pickey ... takes 5 min... faster than changing the oil..
Tip.. start with the fastest moste lojical remidy then work down the list....   IE: 1 adjust clutch cable: 5 min....   still not fixed ? 2: change oil 10 min.... still not fixed...?  3: Search function "clutch slipage" 15 min (If like me u cant spell) changin the clutch for a new 1 should be at the bottom of the list... no need to spend money on oil.. filter.... clutch.... ece when it might be free.. (adjusting the clutch cable)
good luck!
sorry if i just pointed out the ovious...The sky is blue if u hadent noticed

i have used the search function, and read through a lot of posts. but as it is quite clearly a question and answer FORUM then i see no harm in making a new post. if i wanted to simply read i would have wouldnt i?

the grass is green incase you hadn't noticed

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?

mabe i caused harm.. sry if i came off wrong... evry problem i have searched for i found lots of ppl have had the same problem.
problem fixed.... thanks gstwin

2bad the clutch adjustment dident work.  that vid is gold.

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

I just did my first clutch job yesterday, It was on my CBR but I think most bikes ore pretty simmilar. I was amazed how easy and quick it was. Now I'm going to slip the thing more, dragstrip launches etc! When mine was slipping the plates were still above the minimum spec so maybee bad oil from previous owner. The springs were still within spec, when I ride it on dry roads I'll see if it fixed my problem. If not, I'll need to get some stiffer springs.