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1964 CB77 transmission and/or clutch issue in 2nd gear.

Clutch, Transmission, Drive Chain, Sprockets
apophis
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Posts: 62
Joined: Mon Sep 17, 2012 11:02 am
Location: Denver, Colorado

1964 CB77 transmission and/or clutch issue in 2nd gear.

Post by apophis » Fri Apr 26, 2013 11:18 am

I am having (2) issues with the CB77 I got last year. One has always been a problem. one is new. I am not sure if they are related.

1. Shifting/Clutch. 1-2-3-4 is always fine. 0 issues hitting Neutral, but downshifting. If I am below 2000rpm shifts to 2nd fine. Above 2000 rpm's, it clicks like it shifted, but I am in N as though I went past 2nd. I have to click up to hit 2nd. There have been a few times where the bike would not leave the neutral state when this happened. it would not shift up or down until the bike was shut off. It might do this all day, or skip several days. I have not disassembled yet, but I was guess it would be the star at the end of the shifter drum. Just looking for input.

2. a new problem, also related to 2nd gear has been randomly happening for ~ 3 weeks. From a dead stop (takeoff) after shifting into 2nd and ONLY if the bike is turning under acceleration, it is accelerating fine under normal throttle (not gunning it and the clutch does not appear to be slipping), for a second it will act as though the bike is not in gear, then the bike lurches as though I am gunning it and hot 2nd gear into place with a hammer. The feel is mechanical (tranny) and not like a clutch issue. As though I slammed it from 1st to 2nd without using the clutch at all. then the bike acts normal, shifts fine up and down and it might not happen again at all until I am shifting in a corner again and only from a dead stop. not if i was riding into a corner and downshifted to 2nd. At a loss on this one

LOUD MOUSE
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Posts: 7817
Joined: Mon Aug 15, 2005 8:23 am
Location: KERRVILLE, TEXAS

Re: 1964 CB77 transmission and/or clutch issue in 2nd gear.

Post by LOUD MOUSE » Fri Apr 26, 2013 12:26 pm

I suspect you have warn dogs on the gears.
One question. What angle is the shift part on the shift shaft?
Is it 12:00/11:00/13:00?. ....lm

apophis wrote:I am having (2) issues with the CB77 I got last year. One has always been a problem. one is new. I am not sure if they are related.

1. Shifting/Clutch. 1-2-3-4 is always fine. 0 issues hitting Neutral, but downshifting. If I am below 2000rpm shifts to 2nd fine. Above 2000 rpm's, it clicks like it shifted, but I am in N as though I went past 2nd. I have to click up to hit 2nd. There have been a few times where the bike would not leave the neutral state when this happened. it would not shift up or down until the bike was shut off. It might do this all day, or skip several days. I have not disassembled yet, but I was guess it would be the star at the end of the shifter drum. Just looking for input.

2. a new problem, also related to 2nd gear has been randomly happening for ~ 3 weeks. From a dead stop (takeoff) after shifting into 2nd and ONLY if the bike is turning under acceleration, it is accelerating fine under normal throttle (not gunning it and the clutch does not appear to be slipping), for a second it will act as though the bike is not in gear, then the bike lurches as though I am gunning it and hot 2nd gear into place with a hammer. The feel is mechanical (tranny) and not like a clutch issue. As though I slammed it from 1st to 2nd without using the clutch at all. then the bike acts normal, shifts fine up and down and it might not happen again at all until I am shifting in a corner again and only from a dead stop. not if i was riding into a corner and downshifted to 2nd. At a loss on this one

apophis
honda305.com Member
Posts: 62
Joined: Mon Sep 17, 2012 11:02 am
Location: Denver, Colorado

Post by apophis » Fri Apr 26, 2013 12:28 pm

12:00. I tested moving it to 11:00 last week, but that changed nothing so I moved it back to where it was when I got the bike

LOUD MOUSE
honda305.com Member
Posts: 7817
Joined: Mon Aug 15, 2005 8:23 am
Location: KERRVILLE, TEXAS

Post by LOUD MOUSE » Fri Apr 26, 2013 12:34 pm

The part should be at 11:00 not 12:00.
Get on you knees and look at the linkage at the location of the pin and you will see the part with the pin is hitting the lever when you shift from 1st to 2nd which doesn't allow the shift drum to turn enough to change gears.
You might want to try 10:30. .......lm

apophis wrote:12:00. I tested moving it to 11:00 last week, but that changed nothing so I moved it back to where it was when I got the bike

Jlovvorn
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Posts: 477
Joined: Tue Dec 27, 2011 11:10 am
Location: Washington DC

Post by Jlovvorn » Sat Apr 27, 2013 9:17 am

I had this exact issue on my cb77, and was about to tear open the bottom end, but now it's manageable, with three fixes.

1. As per Ed, put the shift thumb pointing at 10pm, rather than noon where I had it.

2. Preshifting when I am coming down from 4/3 and 3/2. You can google this method, if like me you never heard of it. Just be careful, as 1/3 times I preshift from 3/2, it just drops right into 2 without clutch.

3. Come to a nearly complete stop before shifting from 2/1. Wait until the last second. This eliminated all of the hang ups I had coming from 2/1 (on is bike and my 550).

This may all be basic stuff, so forgive me if I am telling you stuff you know.

#2 and 3 were revelations in my vintage Honda riding experience, and made evening way more enjoyable.

Jlovvorn
honda305.com Member
Posts: 477
Joined: Tue Dec 27, 2011 11:10 am
Location: Washington DC

Post by Jlovvorn » Sat Apr 27, 2013 9:19 am

PS I also switched to a mix of 30wt ND and Honda HP4, which is supposed to help manage the 'character' common to shifting these old bikes.

apophis
honda305.com Member
Posts: 62
Joined: Mon Sep 17, 2012 11:02 am
Location: Denver, Colorado

Post by apophis » Sat Apr 27, 2013 4:07 pm

i put the shift thumb to 10. seemed to shift better up and down, but the lurch in 2nd didnt change. once I have time I will take that side off. while i am in there, i might replace the clutch plates. how many should a 64 have? I have heard the # varies

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