Clutch Slip at high power

[FaceDeAce]

Been surfing through the old threads looking for a good one to bring forward.  Found some stuff but to summarize my issue, decided to post anew.

the bike:  resurrected 1984 venture royale

the problem:  bike is running better and better each ride, and getting stronger!  It was great for about 150 miles of test rides.  Now recently when I really lean into the throttle when it gets to 3500 rpm range and engine torques up, the clutch slips. Back off throttle and it grabs again.  Normal driving is fine. Only happens when tapping into the high engine power condition.

possible causes, and questions. Please comment:

1. The bike is showing 42,000 km on the odo.  I do not know if this is 42k or 142k or 242k …  I have been thinking of replacing the clutch springs, as are cheap$ to do.  Does this bike have the 6 coil springs or the silly diaphragm spring? DoI need to drain the oil before taking the clutch over off?

2. For the first while and rounds of testing to get then engine cleaned up I just used whatever half oil jugs I had around the shop. Mostly car/truck gas and diesel synthetic oils. Now that it is clean and running great I did do a did final oil change a couple days ago with Dino 20w50 motorcycle oil.  The clutch may not have liked the other oil.  I do not have much of any runtime yet with the current oil to see if the slippage will clean up just from the oil change.

3. When I started on this basket case it had no clutch fluid, none, completely empty and gunked from years of sitting. Filled and purged with fresh fluid(dot3). I did not remove or clean the slave. Perhaps it is gunked internally and sticking.  I also do not know if I bled the system properly when filling. Added fluid to the handle and pumped. Opening/closing the bleeder with each pump.  There may be air but I doubt it.

4.  One of the threads mentioned two holes in bottom of the master cylinder.  I see one hole that is through and through it can see the cylinder moving and picking up fluid.  There is a second half-drilled holed next to it. That hole is not through and nothing can be seen in it nor any fluid going in or out of it.  Please explain this further/clearer.  As am wondering if I need to drill it through?

as a start …..   thanks folks.  This is a great venture community.  Looking forward to some pointers to sort this out, and hopefully without the spend of replacing the clutch pack.  Hoping is something else.

 

Edited July 27 by FaceDeAce

[FaceDeAce]

PS: there are no other clutch problems such as creeping or sluggish engagement. The lever hand pressure is good and has a nice reasonable feel to it. The issue is only clutch slippage under high power condition.

 

Edited July 27 by FaceDeAce

[Marcarl]

3 hours ago, FaceDeAce said:

Been surfing through the old threads looking for a good one to bring forward.  Found some stuff but to summarize my issue, decided to post anew.

the bike:  resurrected 1984 venture royale

the problem:  bike is running better and better each ride, and getting stronger!  It was great for about 150 miles of test rides.  Now recently when I really lean into the throttle when it gets to 3500 rpm range and engine torques up, the clutch slips. Back off throttle and it grabs again.  Normal driving is fine. Only happens when tapping into the high engine power condition.

possible causes, and questions. Please comment:

1. The bike is showing 42,000 km on the odo.  I do not know if this is 42k or 142k or 242k …  I have been thinking of replacing the clutch springs, as are cheap$ to do.  Does this bike have the 6 coil springs or the silly diaphragm spring? DoI need to drain the oil before taking the clutch over off?

6 springs all torqued to about 6 ft lbs. Don't need to drain the oil if you put it on the side stand.

2. For the first while and rounds of testing to get then engine cleaned up I just used whatever half oil jugs I had around the shop. Mostly car/truck gas and diesel synthetic oils. Now that it is clean and running great I did do a did final oil change a couple days ago with Dino 20w50 motorcycle oil.  The clutch may not have liked the other oil.  I do not have much of any runtime yet with the current oil to see if the slippage will clean up just from the oil change.

This MC has a wet clutch and doesn't do well with friction modifiers. I use only diesel oil. 42k is a bit early for the clutch to slip, but from what to describe it is slipping. Run it a bit and then change the oil again, might, might solve the issue.

3. When I started on this basket case it had no clutch fluid, none, completely empty and gunked from years of sitting. Filled and purged with fresh fluid(dot3). I did not remove or clean the slave. Perhaps it is gunked internally and sticking.  I also do not know if I bled the system properly when filling. Added fluid to the handle and pumped. Opening/closing the bleeder with each pump.  There may be air but I doubt it.

The second hole is there, it's so tiny you'll need a light on the other side to see it, but it will clog up at times. use a very thin copper wire to open it when the master is apart.

Sometimes air can get stuck at the master, tap the end of the master with the handle bars turned fully to the right and lightly pump the handle, altogether now.

4.  One of the threads mentioned two holes in bottom of the master cylinder.  I see one hole that is through and through it can see the cylinder moving and picking up fluid.  There is a second half-drilled holed next to it. That hole is not through and nothing can be seen in it nor any fluid going in or out of it.  Please explain this further/clearer.  As am wondering if I need to drill it through?

as a start …..   thanks folks.  This is a great venture community.  Looking forward to some pointers to sort this out, and hopefully without the spend of replacing the clutch pack.  Hoping is something else.

 

 

[FaceDeAce]

Marcarl, thanks for your t thoughts on this (and the other topics. 👍).

I know the mixed concoction of other oils were not ideal for this.  That stuff is gone and it has proper motorcycle oil (for wet clutch) in it now, the 20-50 just put in should clear up the issue, if it is/was oil related.

I will check that teeny tiny hole in the master cylinder. If there is one, it is definitely plugged. Still do not understand why it is there though. .

if the oil does not have to be drained to check the clutch pack, that’s great.  I’ll pull the cover Monday evening and check the set for wear or glazing.