My 1981 Suzuki GS250T (3,600 miles) experienced clutch slip the other day going up a steep hill in 4th gear.
The steel plates look fine and the clutches don't look bad. I'm wondering if the Mobil T4 is too slippery an oil for a bike such as this.
I'm in a time crunch because I have the Reliability Rally next weekend at Tail of the Dragon.
WWGRMD? I do have new clutches coming (maybe even in time). Was considering sanding the steel plates to roughen them up and adding a washer to each spring to preload them a bit. Thoughts?
I'm surprised a GS250 has enough juice to slip the clutch; I always assumed those were the same bottom end as the GS425/GS450 with the same clutch bits.
Mobil 4T? T4 is a Shell oil that is not MA rated, so not rated for wet clutches. The Mobil stuff is MA and MA2 rated, so you're good to go if you are using that.
Assuming it's an old or original clutch, someone probably used something not MA rated at some point, so you need new fibers. I generally prefer OEM; have had issues even with some name brand aftermarket stuff. Clean the steels with brake cleaner. Those are not glazed or overheated from the pic you posted, and I personally like those OE style perforated ones. Many aftermarket steels are smooth, which have a different engagement feel. Check on a piece of glass to make sure the steels are flat, but they don't look burned so I would be they are fine.
Make sure the basket isn't notched - pretty unlikely on a street bike at that mileage.
Make sure you have enough free play in the clutch cable. I see this one a lot - someone adjusted the lever a little too tight and the clutch slips. Have seen a few old bikes where the clutch cable is gummed up so it preloads the clutch open and causes slip as well. Doesn't take much at all.
Are the clutch springs still in spec? Replacing them can help if not, and there is usually an "HD" aftermarket option for older bikes. The washer trick only works if the ID of the washer is larger than the OD of the threaded boss that the spring goes around, otherwise the washer just gets clamped to the face of the boss rather than providing any more preload. This can help but stiffer springs make a bigger difference if you can get them easily.
It's hard for me to even find the spec for things like the springs. I'll see what I can find for HD springs though.
Fresh friction discs and a new clutch cable and she's unable to power through the clutch now. Happy happy
