Author Topic: CB750 K1 cam lobe measurements  (Read 154 times)

Offline WestYorkshireBiker

  • SOHC Associate
  • Posts: 72
    • View Profile
CB750 K1 cam lobe measurements
« on: April 05, 2021, 01:14:41 PM »
Hi. Are these the correct lobe measurements for a K1 cam as I've looked in the manual which says
Inlet 35.86mm
Exhaust 35.36mm
Mine are a bit under in most cases so I suspect a new cam is in order but thought I'd check first! Ta.

Sent from my AC2003 using Tapatalk

OW MUCH????????????

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #1 on: April 05, 2021, 01:50:44 PM »
To the second decimal place they are both at minimum dimensions from manual.

They don't actually wear much at all if the oiling has been good as the load bearing surface is pretty big for what it has to do.

Assuming that surface of cam and rocker faces are good,  then they would appear to be ok to continue.

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #2 on: April 05, 2021, 02:01:03 PM »
Oops, just read that's the manual spec you've quoted (I thought it was measured amount  :-[ ) are yours far away from spec?

It's just as important if it has any surface pickup that would be poor for continued running.

Any detailed pictures of lobe peaks?

Offline WestYorkshireBiker

  • SOHC Associate
  • Posts: 72
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #3 on: April 05, 2021, 02:44:40 PM »
Oops, just read that's the manual spec you've quoted (I thought it was measured amount  :-[ ) are yours far away from spec?

It's just as important if it has any surface pickup that would be poor for continued running.

Any detailed pictures of lobe peaks?
I'll check again tomorrow and take some pics. Thanks.

Sent from my AC2003 using Tapatalk

OW MUCH????????????

Offline WestYorkshireBiker

  • SOHC Associate
  • Posts: 72
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #4 on: April 06, 2021, 11:24:17 AM »
Oops, just read that's the manual spec you've quoted (I thought it was measured amount  :-[ ) are yours far away from spec?

It's just as important if it has any surface pickup that would be poor for continued running.

Any detailed pictures of lobe peaks?
I'll check again tomorrow and take some pics. Thanks.

Sent from my AC2003 using Tapatalk
I've recorded a video of the camshaft with measurements at the end (excuse the camera work!!) https://youtu.be/qGQAISnTevo

Sent from my AC2003 using Tapatalk

OW MUCH????????????

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #5 on: April 06, 2021, 08:23:40 PM »
A little wear there but certainly not trashed. Some look like they've run with below normal clearance from the polishing on the base circle (usually takes it's toll on the lobe peak as well by breaking down the oil film) with some of the peaks showing pickup artifacts, but polished off through running. And maybe a little oil condition past it's best mixed in too.

Probably desirable to replace in pure technical terms,  but doubt it would give problems if run again. Could also dress off the lobes with flat oilstone to restore surface finish. Guess it depends on availability of substitute if you go that way.

Do the rocker faces look serviceable?

Offline WestYorkshireBiker

  • SOHC Associate
  • Posts: 72
    • View Profile
Re: CB750 K1 cam lobe measurements
« Reply #6 on: April 06, 2021, 08:44:30 PM »
A little wear there but certainly not trashed. Some look like they've run with below normal clearance from the polishing on the base circle (usually takes it's toll on the lobe peak as well by breaking down the oil film) with some of the peaks showing pickup artifacts, but polished off through running. And maybe a little oil condition past it's best mixed in too.

Probably desirable to replace in pure technical terms,  but doubt it would give problems if run again. Could also dress off the lobes with flat oilstone to restore surface finish. Guess it depends on availability of substitute if you go that way.

Do the rocker faces look serviceable?
Thanks for the reply. Checking the rockers and housings / shafts tomorrow so I'll get back on that. First eyeball I did earlier two look scored to be honest but might be wrong. Thanks.

Sent from my AC2003 using Tapatalk

OW MUCH????????????

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal