Gl1200 new clutch/ transmission slipping

[Lockhartwings]

I have a new to me 85 GL1200, supposedly rebuilt, looks and sounds great. Mechanic said new clutch installed. But it's very slow to take off in any gear, definently power loss at drivetrain. Engine is strong. Good rpms. Slow to catch up at rear wheel. Im new to Goodwings. Im mechanically inclined. But, Any suggestions what to look at?

[CrystalPistol]

Might bleed the clutch at both mc & sc ends, and check for trash in return port at mc.

[Ohara]

Could be the wrong synthetic oil. If oil used has friction modifiers clutch will slip.

[CrystalPistol]

Could be the wrong synthetic oil. If oil used has friction modifiers clutch will slip.

Yes for sure, could be …. worth an oil change to find out. Did this "mechanic" also own the bike?

[Commander]

I bought a GL1200 bike with this same problem (AND same story, new clutch installed by someone else). I figured hey, why not try to fix it, so I trailered it home and had a quick look. Turns out, both the washers on the banjo bolt at the clutch master cylinder were on the same side, (there should be one on each side), so it was partially blocking the little hole for the hydraulic fluid. So what was happening is there was enough force from the clutch lever to push the fluid down and disengage the clutch, but the clutch return spring was not strong enough to force the fluid back up past the restriction. I fixed that issue, used NEW Dot 4 fluid (change it while you are at it) bled clutch at master cylinder (when you tighten banjo bolt back up, make sure clutch lever is still held in or else it sucks air in and you are not accomplishing anything). Then bled the slave cylinder at bottom (again, make sure clutch lever is held in when you tighten up the nipple). Then bang, i bet you get your clutch biting hard again. This is a common oversight, even for mechanics, so give it a try please and let me know if that helps.

EDIT -> You will want to make sure you don't get fluid on your paint when bleeding master cylinder, so cover your bike with plastic or a rag. That stuff destroys paint. I also made sure to use non-synthetic oil just in case, and even went with 20W50, even though the issue really wasn't with the oil in the end. Sure runs good now though!

[jimmyschow]

i think the oil answer could the ticket here, if not i would bleed the hydraulic clutch line from the bottom up. I know i am going to get lots of crap about this but that is exactly how honda did it in the factory in Ohio when they made these bikes there. Take the bleeder out at the slave cylinder, wrap a bit of thread tape over the threads to help seal it. Now use a syringe like a turkey baster with clear hose on it to push the fluid in. Make sure you bleed at the banjo joint first. go slow or you will shoot DOT 4 everywhere. It will destroy your plastics, so cover the bike. Also clutch plates should be soaked for several hours prior to installation.