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Hello all... long time reader of the forum, first time poster. I have been having some issues with my 74' CB 750 and I wanted to get a crowd sourced thought cluster of what might be wrong. I had two diagnosis... and I am looking to see what everyone thinks.
My gears were always a littler hard to get into neutral... not a big deal, just felt like it wasn't fully disengaging. Got worse @ the end of long rides. Then the bike started hiccuping @ 4000 RPM in second (short lag, then burst) Now second is gone... falls right out. Then 1st started hiccuping and now has a hard time catching.
Some people tell me it can be as simple as the clutch plates... others tell me, it can be the shift fork and drum... I want to do the repair myself, but I am a little intimidated by the idea of cracking the case and fixing the shift fork and drum... but also intimidated by a mechanic bill!
-MD
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Administrator
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It could be either, or both. I would start with the clutch, since it is the easiest, and cheapest to fix. However splitting the cases is not that hard. You do not even need to remove the top end to do it.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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FIRST....How many miles are on the motorcycle?
I doubt it is a transmission problem.
When you say hiccup ing what does that mean?
Can you please tell us what kind of intake system it has?
What kind of exhaust system?
IS the electrical system been kept up?
On a Roadstar Adventure.
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Thanks guys...
By "hiccup"... I mean, @4000 RPM it would fall as if you dropped off the throttle 1/3 for a second, then hit full throttle for half a second, then back to original speed.
The electrical has been kept up. The exhaust is a 4 into 1 from RC Performance... there is about 19,000 miles on the bike (wow I put a lot of miles on it)... last tune up (oil and carbs) was about 800 -1000 miles ago. The bike has been podded and tuned to be so... the only other thing I can think of is the super coils system (I was told by a mechanic that worked on the bike that it had this... don't know what it is) and the small oil cooler that is on it.
Thanks for the help... the wife and daughter are going to be gone next week, so I am thinking of taking it apart soon!
-MD
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M F2 hick-ups  If the choke is not all the way in I noticed,It's dark when leaving house in morning and don't use after much that. Just my 2 cents wirth keep the change 
1977 CB750 F2 Super Sport
<LET THOSE WHO RIDE DECIDE><RIDE TO LIVE-LIVE FOR JESUS>
Native American from central Cal, Kickstand UP in S.W.Missouri,
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Good thing you did not take apart the transmission or clutch.
If this bike has pods and 4 into 1 exhaust it will NOT run right with stock jets.
You are going to have to find out what size main jet, idle jet and slide needle position are.
You have the carbs off so now is the time to make sure the idle jets are clear too.
I do not know what that coil thing is about. .
On a Roadstar Adventure.
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At 19,000 miles it does not need any transmission work.
On a Roadstar Adventure.
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But would an injection issue force the gears to slip and not catch?
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Administrator
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No.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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Took apart the clutch today... didn't see anything too worn.. plates looked fine. Suggestions on what I should look for before I put her back together?
-MD
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Administrator
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Best thing is to check the FSM. It has the minimum reusable thickness' for the friction plates. That,and see if they are glazed or burnt looking.The friction material is just cork,so keep that in mind while looking at them.Oughta be fairly soft. If you cant sink your fingernail in them at least a smidge they might be burnt/hardened.
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Clutch plates may look fine but might slip.
If the bike was sitting for years I would replace the clutch fiber plates.
What happens is when the bike is sitting the cork material is partially
submerged, and part of it is not in the oil so the plates are not consistent in thickness.
Also remember about tolerance stack up.
One plate may only be off .001 thousandths but when you
add up all the plates then it could be 7-.008 thousandths.
On a Roadstar Adventure.
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WARNING !!!
Be very very very careful when putting on the lifter plate, or it will break.
As you tighten the 4 bolts keep tapping the plate with a screw driver handle.
It breaks when one of the 4 ears of the lifter plate gets hung up.
Many articles written about this plate. Do not be the next victim.
On a Roadstar Adventure.
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splitting the cases is not a big deal..you dont even need to take he top end apart to get to the tranny.
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Thanks guys. I hear a rattle coming from the left side of the engine, so I am going to crack it open this week. I have my fingers crossed.
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Administrator
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I know it's not on the left side of the engine,but clutch rattle is normal on these bikes. Especially on the pre-76 models,when Honda made an upgrade/fix for the rattle. I'd hate to see you tear your engine down if its not needed. Also, concerning the hard to find neutral: There are 3 o-rings that seal the oil pump the the engine. Over time those o-rings shrink up considerably. It can cause a loss of oil pressure.Not enough to injure the motor,but enough to cause shifting issues. Without adequate oil pressure the clutch plate tend to stick more than normal. There is another o-ring that tends to shrink and cause issues,too. On the left side of the bike,behind all the shifter mechanism, is a cover that directs pressurized oil the a transmission bearing(not sure of the actual name). Replacing those o-rings made my bike like new when trying to find neutral.BIG difference.
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when you drained the oil, was there anything in it that shouldn't be? If not you maybe spot on about the fork shifter. Just my one cent! 
American by birth. Cowboy by choice!
Vero Beach, FL
http://i373.photobucket.com/albums/oo172/grandpaslinger/HD%20Road%20Glide/IMAG0046.jpg
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The shifting forks should be fine with such low milage, unless it was abused or ridden by a beginner.
But if this bike shifts into all the gears there is NO need to split the cases especially with such low milage.
On a Roadstar Adventure.
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Abuse is the only reason I see a shift fork could be bent. Of course there is always the person who does wheelies...that could cause other issues all together. Just saying!
On Wed, Sep 12, 2012 at 9:59 AM, Lucky 1 [via Honda CB750'S] <[hidden email]> wrote:
The shifting forks should be fine with such low milage, unless it was abused or ridden by a beginner.
But if this bikes shifts into all the gears there is NO need to split the cases especially with such low milage.
Working on a CB750 Digger named Rover
American by birth. Cowboy by choice!
Vero Beach, FL
http://i373.photobucket.com/albums/oo172/grandpaslinger/HD%20Road%20Glide/IMAG0046.jpg
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Thanks again... I am going to check out the O Ring thing first... that sounds like a good start. Here is what happens right now.
Taking off out of first... it has a hard time getting into gear. Catch slip, catch slip... rattle rattle rattle.... in second, it goes in then slips out almost immediately (no rattle)... if I get it into third... smooth sailing through forth and fifth...
no clue... I took apart the clutch... looked fine... the oil was clean... no cork or anything...?
Next I will check the O-rings. I have Tuesday off... I will let you guys know what happens.
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