I actually wrote Seafoam about this very question.
Here's the exact email I sent them:
I was wondering if you could tell me if Seafoam is ok to use in the
crankcase of a motorcycle that has a “wet clutch” ?
I use Seafoam regularly in all my vehicles except my motorcycle and
simply did not because I was concerned about the effects it may have on
the wet clutch, since the engine and transmission oil are shared.
Is there any problems that Seafoam would cause in a wet clutch application, such as clutch slippage or premature wear?
Thanks for your help!
Here's the response that I got from the email:
I sure hope you are experienced enough with Sea Foam to know running Sea Foam in your FUEL in this bike is a YES, as there is NO CONNECTION between the fuel system and wet clutch/oil system.
If not, DO IT!!!!!
As for your oil system/wet clutch shared oil, Sea Foam in the oil at 1 1/2 ounces per quart of that shared oil is what is recommended, to clean old Oil residue back into liquid and dry moisture to prevent ware.
This is your wet clutch's BEST KEPT SECRET
Now, judging by his response, he kinda sounds like a moron.
There's no connection between my fuel system and my wet clutch?
Uh... well DUH! I didn't say there was nor did I ask anything about it.
It also prevents "Ware" ???
Houseware, silverware, tupperware? Maybe he meant "wear".
... the Saga continues.
Seafoam makes a product called "Trans Tune".
I'd be more apt to use that in my wet clutch motorcycle (as of now)
than I would regular Seafoam.
Automatic transmissions have clutch packs very similar to the clutches
in our bikes... The "trans tune" should be better suited to the clutches
in the bikes than the regular Seafoam.
The best thing you can do is use a good quality oil and keep it changed... and you don't need to worry
about using a cleaning agent.