There are several seals that can leak in this area. You say you replaced the mainshaft seal in the back of the primary. I've seen a lot of people replace this seal only to have it start leaking immediately. The reason was that they didn't know you must lubricate the seal before you reinstall the primary cover. When you put the primary cover on with the seal dry, when the engine starts up, the mainshaft immediately goes to 1000 RPM or higher with no lubrication on the seal. The friction burns the lip of the seal up before the lubrication in the primary can get there. It only take a second, literally.
Other seals that can cause leaks in this area are the large final drive gear seal in the face of the transmission behind the front belt pulley and the "Quad" seal that is inside the transmission. The Quad seal is almost like an O-ring. It's purpose is to prevent transmission lubricant from seeping out through the splines of the final drive gear. If the front sprocket splines wear and the sprocket gets the slightest bit loose, the compression on the Quad seal will be lost and the tranny will leak. The tale tell sign on this leak is that the transmission will leak a spot of oil about the size of a quarter or a bit bigger when you park the bike. If you wipe up the spot, it won't leak anymore until you either ride the bike or simply start the engine. Then it'll leak that quarter sized spot and stop. Check your lube level in your transmission.
Whenever I pull the inner primary and the belt on a Big Twin, I replace ALL the seals. Make sure you lubricate the lips on the seals so they don't cook before lubrication can get to the seal.
Good Luck
Steve
5,206 views
Usually answered in minutes!
×