1981 CB750C wont go into neutral while running?

[ndbert15t]

First post here out of almost pure frustration.  I just bought this bike a few weeks ago for 1100 off a guy getting stationed overseas.  The bike starts and runs like a champ.  The issue I am having is that it wont go into neutral with the motor running.  All the other gears catch beautifully and it shifts like a dream until I decide to go to neutral.  Does anyone know if there is a how to on adjusting linkage or do I have another issue?  I have been an aircraft mechanic for the last 13 years so I am somewhat mechanically inclined but I am now realizing working on a turbine engine and a 32 year old motorcycle are very different animals.  Humbling yes but a project I am really excited to get into.

[TOOLS1]

You can download the factory service manual from the home page here for free. It will show how to adjust the clutch. These bikes are designed to skip neutral when shifting from first to second gear, but catch neutral when shifting down from second. I know a lot of people try to shift into neutral from first, and it just does not work on some bikes.
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[ndbert15t]

Tried shifting from both first and second and neither works while engine is running.  Check to see if it was a hot and cold issue and it is not.  Followed the manuals as suggested and found out my shift linkage is some cobbled together parts.  Goes to show that you never trust the PO to have done it right.

[Hoosier Daddy]

As a note, sometimes on my other bikes it helps to hit neutral while you are still rolling.
To sit stationary and fumble up and down on the shift it may blow right by... If you are sitting in the driveway might try a combination of pressure on the shifter while rocking the bike front and back.
  Also no proof of this, but I think a high idle speed doesn't help matters.

(Says the ex Criew Chief  )

[Lucky 1]

If the idle is too high it will make it difficult to put into neutral.
Also moving the bike slight forward or backwards will help.

Remember when you are shifting that the shifting forks are trying to push a gear with 4 holes in the side of it to match up to a gear with 4 pegs or protrusions sticking out of it.

Motorcycles do not have synchros in them like cars do.

[ndbert15t]

Nice seeing another former Crew chief working some of the same issues I am.  My problem turned out to be the sleeve and bushings in my shifter were way worn out and I was having to put more pressure on the shifter to get a gear change and I was just blowing right by neutral.  A little research and scavenging and it shifts just fine now.  I have moved on to trying to figure out where my front wheel came from so I can get a speedometer gearbox that wont turn the cable backwards.

[Lucky 1]

I was a turbine engine mechanic too, but first I was a motorcycle mechanic and still am.

It was always tricky getting these bikes into neutral. You have to use some sensitivity.
You cannot just kick the shift lever down or up.

You need to put the bike in first gear and then lightly lift up on the lever with your toe on the shift lever.
If you have a neutral light it will help.

If the idle is too high it will make it very hard to put into gear. or into neutral.
One way you can feel it is to reach down and when it is in first gear pull up on the shift lever with your hand and you can feel it.
It is 1/2 step not a whole step. So you cannot just bang down on the lever or lift up the lever ALL the way it is part way up to go into neutral from first gear.


Rev it up just a little with a quick blip of the throttle then move the shift lever.
Also just rocking the bike forward or back just a few inches will help.

What is happening is you are trying to get four small round pegs on one gear to line up with the gear next to it with four round holes.

If you stomp on the shift lever it will just bend the shifting forks and damage the transmission.
So being macho will cost you.

[theo305]

Hello
I have the same problem .when engine running there's no way to find neutral,also have another issue.Some days as the engine warming up shifting becomes harder to any gear.If the bike is on center stand and engine running its easy to find neutral .I have replace the clutch disc and springs  but didnt help.My bike is a 1981cb750f.

[shinyribs]

If you notice a difference in finding neutral/gear changes as the bike is getting warmer that it usually,in my experience, a sign of worn out engine oil. These wet clutches don't seem to like thin,beat up oil.

Try an oil change and see if it helps any. Hope this helps!

[theo305]

Thank you for information
Ihave changed oil with French brand  MOTUL 20-50W and now shifting is smoother even when engine is warming.
This oil states that is specially for wet type clutch.
About oil capacity  4lit is enough?(I am from europe I don't know how to mesure in gallons)
I have modified the bike  with an oil cooler from a cb 900f also changed oil pump and oil pan.
Does it need more oil?
As for the neutral problem  yesterday I was talking with an old mechanic he checked the bike and he was100% sure that its a clutch problem not forks or anything  worst.He said he can fix it but I have to leave the bike for 2days...
The problem is that I don't trust to leave my beauty to anybody.I am working on this project  since last summer and I want to finish it my self.
(I am sorry for my bad english I am GREEK )

[cdaiscool]

Liters are essentially quarts, 4 liters = 4 quarts = 1 gallon.

I would make sure to check the dipstick after running it through a quick set of gears. That way the oil can get to where it needs to go, then let it sit for a few minutes and check it.

[free2ride]

oil capacity: 4.5ltr [dry]

[Lucky 1]

Did you roll it back and forth a little while trying to get it in nuetral?

[theo305]

Neutral problem solved!!!
Hello guys,I have very good news.
The problem was hiding in the clutch basket.
After understanding that the problem was that the clutch discs don't fully disengage I made an inspection on the clutch basket and find that the canals that the discs edges are moving inside where hammered from discs.
The result is that discs edges cannot move freely in the canals.
After some research I have used a very cheap method to fix it.
You have to use a thin file and carefully clear the cannals from the hammered spots.After I used a 400 wet sandpaper just to remove any scratches left.
Now my bike can go to neutral very easy also I have a smooth shifting for all gears .
You can use this method by your own risk!!!
Be Carefull don't overfile the basket canals.
Again I am sorry for my bad english

[TOOLS1]

Glad you found the problem. Most people will never think that the clutch could cause a shifting problem.
About your English, you do not use the word "like" 5 times in every sentence, or double negatives, so your English is way better then most college students I know.
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