Changed clutch friction plates (stock type) and springs (15% harder) this evening and also changed the clutch fluid which contained a lot of water and air. The earlier "half-warm slip" at maximum tourqe is now fully cured and the clutch works superb. The friction plate thickness was far above service limit (3.1 mm) but they looked somewhat burned. 8 plates was 3.8 mm and the inner plate, which shall be thinner, was 3.5 mm so they were all well within spec for new friction plates. I went up from semi-synthetic oil to a full synhtetic and now use Motul 300 V Competition Double Ester 100% Synthetic. Since my bike spend almost all of its time at high rpm:s I will continue with that oil which is top ranked. Also read that some people in Sweden have slip problems after changin to Castrol GPS. In my case I really dont know what the main reason for trouble was since I fixed several things at the same time. My best guess right now is that previous owners has used ordinary car engine oil which contains friction modifiers (in case it is higher ranked than API SG), not suitable for a wet clutch.

Kaasari, may be you could try to change the oil to the same as I did as a first attempt, if your clutch still slips half-warm.

I got a new delivery time for the laser exhaust and is now giving up that system. They have changed delivery schedule three times...The bike pulls very fine as is with the dual aftermarket silencers and there is really no need for more power the way I use it. If I am in a real hurry (play mode), I just take the GSX R-1000, but the power of the CBR is really impressing as is. I will probably fix the exhaust next winter by removing the restricted T-section at the end of the stock headers and then mount a single muffler from a 165 hp liter bike. That will cost about nothing since I have the stock silencer from the Suzuki laying around. I've used Yoshi race system on that since it was new.

 

i've noticed a little clutch slip on my bike, usually when it's cold, I think a thinner oil may help.. has anyone ever added limited slip differential additive to the crankcase, or noticed a differance with thinner oils perhaps? I'm thinking when it's cold the oil is thicker and maybe part of the cause. what was the cost of new friction plates for your bike?

 

You should definitly not try "limited slip additive" for a cars rear axle in the bike, if that's what you mean. May be it will make the cluch stop slipping, but its is not developed for a combustion engine and could severly degrade the base oil and lubrication of your engine. The clutch parts where not to expensive, I payed 100 USD for friction plates and new springs, but that's in Sweden and I dont know if it will be more or less in Canada. 4 liters of premium Synthetic engine oil cost about the same here in Sweden (100 USD) to give you a reference. Som people cure slipping bike clutches by putting brackets under the sping bolt heads, to increase spring preassure. I will try to use my bike for many years to come and therefore prefer to fix things the way they should be done (i.e no bracket fixes).

 

alright, it was just a thought I had.. my bike will probably be up for a clutch in 5-10,000 kms in that case.. possibly the same time the CCT will need to be done.. I should do an oil change on it soon, it's been 3000 kms or so

 

It was a really easy work to change clutch plates and springs, less than three hours in total, and I didn't hurry. Drain engine oil and remove the right fairing and then the clutch cover. Loose the five spring bolts and pull out the plate package and clean the steel plates if they will be reused (I did). Soak the new friction plates in new oil for an hour or two, and then put the stuff togheter again. The torque for the spring bolts is 12 Nm on my model (year -92). I thought that I would have to deburr the slider tabs on the friction plates, but they runned so smoth in the cluch basket that there was no need for that. I used a new gasket on the clutch cover.

I also removed the left fairing since I had to bleed the cluch when i changed brake fluid in the clutch hydrualic. I managed to empty the clutch oil reservoir and had to open/close the fitting to the main cylinder a few times (at the handle bar) to get rid of all air in the system.

Dont forget to put new oil in the engine...

 

Thanks alot for the info.

I've had couple of "slips" more, but now they happened like this: 5th gear, full throttle, rpms around 10,000, then clutch lever pulled in and into 6th gear, and when I release the clutch, it won't attach immediately but make a slip and pulls rpms into 11,000, when I ease throttle a little bit, clutch attaches fully and won't slip anymore when turned again to full throttle. I haven't tried to put 6th gear in without using the clutch lever, I think I'll test that too.

It can be definitely caused by that Castrol oil, and even more so if you've heard that some other people have found problems with it. But then, I've used the same oil already for two summers, went couple of times to high-speed airfield runs and it never slipped before. But I think I'll go for a oil brand change just to be sure, thanks for the oil info.

On the other hand, I'm also thinking of changing that clutch spring into harder one. Like you mentioned earlier, stock spring may have hard time when pushed to the limit on systems with more power & torque than in stock. My problem also points to this direction, that the spring isn't able to push plates back together in that specific situation. I'll report what happens.

Sad to hear about that Laser exhaust. But yeah, if you want to mod your stock system, get rid of that T-section. If you've done welding before and have some extra pipe around, it won't be a big job. In case you're bolting that stock silencer from Suzuki, you probably want to open that can and check that it's really straight free-flowing, as stock cans usually aren't. There's most likely some restriction plates inside the silencers holepipe and they can be knocked off with screwdriver and hammer. You could also check from time to time if any ebay etc. sellers have those 1000F full aftermarket systems for sale cheaper.

So, anyone need to buy little used Castrol GPS engine oil?

 

If your friction plates are within tolerance for new plates, as mine where, I guess one could try sand the surface 1 or 2/10 mm and just change the springs to stiffer ones. The springs costed only about 130 SEK at www.addemoto.se If it doesn't work, one could change friction plates later when it's time for next oil change.

I later compared one new and one old spring by putting them end-to-end and compressed to 50% in a vise. There was one extra spring in the new set. The old spring became almost 10 % shorter for the same preassure, initially the had the same lenght within 0.5 mm.

Edit, link didn't work

 

The full Laser system came today. The order was cancelled due to late delivery, but the system popped up at my doorstep anyway. Funny, but OK with me. I'll install it coming weekend and report my findings. On the Suzuki I have a race-baffled Yoshi system. Looking at the Laser system, it appears to be much louder, one can see right through it. In case of to much of the fun, I'll fabricate some insert. There was a dB-killer included, but that is very straight and short so it wont reduce more than a few decibel and was marked 3 dB. To give a reference, 3dB is about the minimum that the human ear will notice as a change in volume. 10 db will appear to be half (or double) volume to people. It also has a visible engraving "not for road use". That had to be sanded down as a part of the road aproval process The finnish, and low restricting pipe work, seems to be fine.

 

Nice to hear!

When I installed my Yoshi system, I found out that new exhaust pipes came very close (less than 1cm) to front fairings at the engine end, so I wrapped some heat-restricting tape (it's meant for car exhausts and can be found in almost all car part stores) to all four exhaust pipe to prevent any fairing melting. Maybe you should check that too, as those pipes become very very hot and glow red when riding it hard and will for sure melt any plastic too near to them (check also that any electric wire won't touch the pipes). The radiator in my bike had a little hard time fitting in with new pipes, so I moved the radiator some cm's forward and had to cut small piece of inner fairing because of that. Are you going to get it dynoed and carbs rejetted? Also waiting to hear how the sound changed and how did you like it! lol at that "not for road use" engraving.

About my clutch: I got new springs friday and opened the clutch yesterday. For my big suprise, all clutch plates were still in very good shape, mass plates bright clear, no signs of burning and friction plates hadn't weared up either. I mixed plate order a little bit (moved friction plates from edges to the middle), got rid of that Castrol oil and put new 10W-40 oil in (my local bike store had some "Genuine Honda motor oil for high-end Honda bikes", very cheap too 30eur/4litres so I decided to test that) and changed all springs into harder ones.

Man, what effect it had! At first it still slipped a little bit, but when old oil weared out from clutch plates and new oil started to kick in, clutch became very sharp and precise. Clutch lever feels little stiffer thanks to harder springs, and the whole system feels now more solid. I pulled some runs with 5th gear up to limiter and like you described too, accelerating was now different. Revs didn't jump up so fast anymore, but you could feel how the bike gained speed faster. Also I even found out how the engine-braking become more sharp and effective, hah there must been some slipping too with old oil/springs!

Many thanks to you when you advised me to check that clutch, I wouldn't probably have noticed to have any problem in clutch myself, as there clearly was.

 

Glad to hear your clutch problem was solved so nicely. I'll check the distance to plastics as you said, thanks for pointing that out. I'm really happy with the new system, the way it looks, sounds and make the bike pulling. I meantioned in another thread that it sounds like an old fighter aircraft at full blast, pure enjoyment to the ears and sole. The new better ground clearence also boost inspired driving, just to watch up not to do silly things when road driving and keep common sense.