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Author Topic: 5th Gear Slip?  (Read 2087 times)

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Offline Hrvatski Medvjed

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5th Gear Slip?
« on: October 08, 2013, 03:40:41 PM »
Hey Folks,

I am having a strange "slip" occur and wonder if anyone can help me diagnose?

Bike: 73 CB500
Symptoms: 5th Gear Slip
When: Highway speeds only (5,000 RPM's or higher). Not all the time either. Cruising along is no issue, it's when I roll on the throttle really hard that it seems to slip.
Definition of the "Slip": RPM's climb but the bike doesn't accelerate.
Current fix: Back off the throttle and then roll on a bit less agressively.

Thoughts on any issues or possible fixes?

Thanks!
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Re: 5th Gear Slip?
« Reply #1 on: October 08, 2013, 04:07:20 PM »
Have you adjusted your clutch?
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #2 on: October 08, 2013, 04:35:38 PM »
Yep. I recently replaced my clutch cable and cleaned/greased the assembly on left side of engine. Pushrod is in one piece and the little steel ball us in place. Shifts great and the clutch actuation feels great. Thoughts?
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Re: 5th Gear Slip?
« Reply #3 on: October 08, 2013, 04:44:16 PM »
The clutch is slipping why I don't know enough about your model I have a 750. Maybe dave or TT will have some ideas. I bet if you put the front tire against a wall with the rear on a hard surface put it in 3rd or 4th it would slip rather than stall.
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Offline nIkbot

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Re: 5th Gear Slip?
« Reply #4 on: October 08, 2013, 05:49:41 PM »
Same on my '73 CB500 across all gears under hard accel/hill.

Dropped the clutch basket and found that the steel plates are slightly warped. Took them out, put them on a sheet of glass and tried to slide a feeler gauge under them. Some of them had one section where it would slide under a little on the thinnest feeler. So just de-glazed them to last the season.

So for the season I replaced the friction plates with new Vesrah ones and flipped the spring washers over. This made the problem a great deal less. Can take off from stand still on hill's and only slips in 3+ when I'm not being respectable to it.
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 5th Gear Slip?
« Reply #5 on: October 08, 2013, 06:11:08 PM »
Are you using bike specific oil? If not drain the oil and go with bike oil.
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Offline goldarrow

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Re: 5th Gear Slip?
« Reply #6 on: October 08, 2013, 06:18:12 PM »
i'm having the exact same symptom as you do.  i'm going to swap out the clutch from my parts motor, as soon as i could find my impact driver
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #7 on: October 08, 2013, 07:27:49 PM »
Yep, 10-40 Lucas motorcycle oil (partial synthetic). This is under hard acceleration only after cruising at a constant speed in 5th.

I'm going to try the "push on the wall" thing and see if it slips. If it does, what's the adjustment I need to make?

Fall color tour road trip planned for Thursday so I'll let you all know how it turns out...pictures too!
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 5th Gear Slip?
« Reply #8 on: October 08, 2013, 07:35:12 PM »
If it's actually slipping vs an oil issue then chances are you're going to need springs and or discs. If it's working good in the lower gears I doubt an adjustment will help 5th but it's worth a try.
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Online PeWe

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Re: 5th Gear Slip?
« Reply #9 on: October 09, 2013, 02:48:15 AM »
My bike slipped on 5:th gear during heavy acceleration. I reduced throttle and full speed again and it felt like having a 6:th gear when it gripped (slipped less)
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Offline bryanj

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Re: 5th Gear Slip?
« Reply #10 on: October 09, 2013, 06:41:44 AM »
Have you adjusted the mechanism as per book, NOT the cable
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #11 on: October 09, 2013, 05:10:25 PM »
Yes, I loosened the lock bolt and turned the huge Phillips style thing-a-mabob clockwise a wee bit.
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Offline Fritz

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Re: 5th Gear Slip?
« Reply #12 on: October 10, 2013, 09:33:04 AM »
Could be anything from oil to clutch adjustment to worn springs, disks or plates.

I was fighting the same problem for two years: clutch slipped after hitting bumps at high speeds in 5th. Until I installed new clutch disks and springs some 500 miles ago: Problem solved.
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #13 on: October 10, 2013, 02:28:36 PM »
Rode just under 200 miles today (beautiful fall day in Minnesota) and it slipped a few times. Not terrible but, enough to know that something's amiss. I'll be replacing the discs and springs soon.

Any recommendations on where to get replacements?
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #14 on: May 05, 2014, 04:15:47 AM »
I finally finished up some other work on the bike and replaced the clutch plates and springs. I'm wondering now if I possibly did something wrong or if it just needs some good adjusting? I ask because I now have slip in all gears when attempting to accelerate (more aggressively). I tried putting the front tire against the garage wall in 3rd gear and the bike just kept revving - no stalling.

Any ideas?

Sorry to bump up an older topic.
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Offline calj737

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Re: 5th Gear Slip?
« Reply #15 on: May 05, 2014, 06:48:06 AM »
Did you inspect the lifter rod that traverses the engine? Is the ball bearing installed on the left end of it?

After replacing the springs and plates, did you then attempt to adjust the cable for the correct amount of engagement and free play?
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #16 on: May 05, 2014, 06:57:18 AM »
Rod is in one piece and the steel ball spacer is in place...

I assume it's an adjustment issue but, the clutch slips worse with the new plates and springs than it did with the old ones. Seems strange.

You can't install the plates backwards or something, can you?
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Offline calj737

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Re: 5th Gear Slip?
« Reply #17 on: May 05, 2014, 07:04:12 AM »
Can't imagine how... Unless you put them on the left side of the engine?  ;)

You did re-install the proper sequence of plates/discs, right? When you clutch plates, do you mean the steel plates or friction discs? I would have replaced all three components, discs, plates and springs at one time. If the steel plates were out of spec, and the springs were too, then stands to reason the friction discs aren't long for this world (unless newer than the other components).

Did you tighten the springs enough?

If all the above is correct, you need to move onto adjusting the clutch cable. Adjust at the side cover first, then move to lever. Also, the adjuster in left side cover can be used before cable adjustment.
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Offline Hrvatski Medvjed

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Re: 5th Gear Slip?
« Reply #18 on: May 05, 2014, 07:56:21 AM »
Friction plates and springs. I was unable to locate the discs for replacement.

Tightened the bolts down...I assume it was enough.

I'll give the adjuster and lever adjustments a look tonight.

Thanks for the insight.
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