Author Topic: Crankcases assembled but can't select gears  (Read 789 times)

Offline ebmbiker

  • Newbie
  • Posts: 45
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #15 on: May 26, 2022, 03:14:16 PM »
Long engine mounting bolt is the correct thread. It's an ill wind that doesn't blow a bit of luck!
"Fast Beat The Feet!"

Offline Sesman

  • SOHC Pro
  • Posts: 944
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #16 on: May 26, 2022, 03:47:14 PM »
Use the rear engine bolt and footrest as a make shift slide hammer. It really shouldn’t be tight. Worked for me.

Offline Sesman

  • SOHC Pro
  • Posts: 944
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #17 on: May 26, 2022, 03:48:19 PM »
Crossed in the ether…

Offline McCabe-Thiele (Ted)

  • SOHC Master
  • Posts: 2317
  • 07505030740
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #18 on: May 26, 2022, 04:04:37 PM »
Sorry I do not think I can help you as it's outside my limited knowledge.

Only question I would ask is was the gear selector drum/selector forks  in the neutral position when you assembled the gearbox internals ?

I can't be sure if it was in neutral. The shift drum guide screw [the part that screws in from the top of the crankcase] that I have is the later version without the ball and spring. So there's nothing to fit into the detent on the drum.
If I remember correctly I fitted the neutral switch so it was obvious when the switch was in the neutral position but mine is a 400.
« Last Edit: May 26, 2022, 04:38:49 PM by McCabe-Thiele (Ted) »
Honda CB400 four super sport

Offline philward

  • SOHC Master
  • Posts: 2423
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #19 on: May 26, 2022, 08:55:31 PM »
To isolate the problem - ie, whether its the selector mechanism or the internal drum/forks/gears is the problem area, can you not remove the external selector mechanism and try to turn the drum with a a large adjustable pair of plyers (with suitable cloth protection on the drum) - you may need to turn the output shaft to help gear selection (mimiking the gearbox moving). If this works, you will know its the assembly of the external mechanism.
It may save you needlessly splitting the cases.
Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Kawasaki ZZR1100D3 (1995)
Kawasaki ZZR250 (1990) Project (Not started)

Offline McCabe-Thiele (Ted)

  • SOHC Master
  • Posts: 2317
  • 07505030740
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #20 on: May 26, 2022, 10:13:52 PM »
Don't rush into splitting the crankcase take your time & try suggestion on here. I was going to  taking my cam cover off as I was sure I had made a mistake when setting the valve timing - as it turned out and thanks to advice here I could check valve timing it was okay. Weeks later I found a photo on my project site showing all was OK.
Honda CB400 four super sport

Offline philward

  • SOHC Master
  • Posts: 2423
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #21 on: May 26, 2022, 10:58:46 PM »


To isolate the problem - ie, whether its the selector mechanism or the internal drum/forks/gears is the problem area, can you not remove the external selector mechanism and try to turn the drum/plates/pins assembly with a large adjustable pair of plyers (with suitable cloth protection on the drum selector mechanism plates) - you may need to turn the output shaft to help gear selection (mimiking the gearbox moving). If this works, you will know its the assembly of the external mechanism.
It may save you needlessly splitting the cases.



Sent from my moto g(50) using Tapatalk

Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Kawasaki ZZR1100D3 (1995)
Kawasaki ZZR250 (1990) Project (Not started)

Offline Oddjob

  • Grogu
  • *
  • Posts: 5468
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #22 on: May 26, 2022, 11:26:51 PM »
The drum is in the wrong position, it’s almost certainly got one of the dowel pins locating the forks stuck down a slot in the drum instead of inside the track where it supposed to run. As you can’t see or get to these pins without splitting the cases you’re going to have to do that.

Learn the lesson, always check for gear selection before you seal the cases. You made a mistake but luckily you spotted it before you put the engine back in the frame, it could have been a bitter lesson to learn but it wasn’t that bad in the end.
Don't play stupid with me, I'm better at it

Offline ebmbiker

  • Newbie
  • Posts: 45
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #23 on: May 30, 2022, 03:26:17 PM »
Good afternoon guys, found the problem. The 4th gear on the layshaft was on the wrong way round!

Because the engine was disassembled when I bought it, I just put the layshaft assembly in as I found it in the box. At some point in the past, the previous owner must have taken off the 4th gear and put it back on the wrong way. Anyway, I can now put the crankcase halves back together.

This leads me on to another question. Do you apply gasket sealant to the big end-bearing joint faces? The ones that house 2, 3 and 4 main bearings? I didn't the first time I assembled it but was thinking it might need it?

Cheers,

JB
"Fast Beat The Feet!"

Offline MrDavo

  • SOHC Master
  • Posts: 1363
  • He who dies with the most toys wins
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #24 on: May 30, 2022, 03:39:30 PM »
Quote
Do you apply gasket sealant to the big end-bearing joint faces? The ones that house 2, 3 and 4 main bearings?

No they should be dry and clean, that's all. My CB750 crank was completely ruined by a previous owner painting the cases all over, including behind the shells. The tolerances are very fine, after painting they were zero or less, ruining the crank and shells.
1969 Honda CL450 'Scrambler'
1974 Kawasaki Z1A
2005 Harley XL1200R Sportster
1985 Porsche 911 3.2 Carrera Sport

Offline Sesman

  • SOHC Pro
  • Posts: 944
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #25 on: May 30, 2022, 04:01:59 PM »
Is that correct? My original and unmolested 550 F2 had cement that I removed with acetone. Just the merest suggestion of goo, just like on the crank case surfaces, but it was there all the same!


Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1
  • Grogu
  • *
  • Posts: 7064
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #26 on: May 30, 2022, 05:03:29 PM »
Quote
Do you apply gasket sealant to the big end-bearing joint faces? The ones that house 2, 3 and 4 main bearings?

No they should be dry and clean, that's all. My CB750 crank was completely ruined by a previous owner painting the cases all over, including behind the shells. The tolerances are very fine, after painting they were zero or less, ruining the crank and shells.
I think you are referring to the outcome of something else Dave. He was asking if he should put Hondabond on all the machined mating surfaces of the crank cases, not just around the main edges of the crank cases.
« Last Edit: May 30, 2022, 05:05:45 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1
  • Grogu
  • *
  • Posts: 7064
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #27 on: May 30, 2022, 05:04:19 PM »
Is that correct? My original and unmolested 550 F2 had cement that I removed with acetone. Just the merest suggestion of goo, just like on the crank case surfaces, but it was there all the same!
Yes, you are correct.
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline ebmbiker

  • Newbie
  • Posts: 45
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #28 on: May 30, 2022, 05:44:12 PM »
So Hondabond on all mating surfaces?

Cheers, JB
"Fast Beat The Feet!"

Offline Oddjob

  • Grogu
  • *
  • Posts: 5468
    • View Profile
Re: Crankcases assembled but can't select gears
« Reply #29 on: May 30, 2022, 05:50:30 PM »
Before you put the case together have you checked you can select all the gears? And does the cutout in the drum now mate up with the roller on the positive selection mechanism when it's in neutral? It should do or there's something else wrong somewhere.
Don't play stupid with me, I'm better at it

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal