Author Topic: 78 cb750f cam chain tensioner adjustment confusion  (Read 3559 times)

0 Members and 1 Guest are viewing this topic.

Offline dboblet

  • Enthusiast
  • **
  • Posts: 173
  • OMG - what did I get myself into this time!!??!!
78 cb750f cam chain tensioner adjustment confusion
« on: August 03, 2008, 08:31:37 PM »
I've been looking through previous posts and find different instructions for adjusting the cam chain tensioner, all different from the shop manual.  Ths shop manual says to start the bike and have it idle, then adjust the tension in the usual way.  Most of the post I see say engine off and have it at either tdc or some degrees before.  so...... which is right???
No matter where you go, there you are.

jjwaller

  • Guest
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #1 on: August 03, 2008, 09:40:25 PM »
Made me look through all the various manuals.
Yes there is confusion these days.
The manuals back in the day said to:

1/4 at TDC  T mark on crank.  Then adjust tensioner.
Never tried the running method on a 750.
That does work on the 400's though.
Turn the engine clockwise with a socket, not the kicker.
Get a much better feel for what is going on that way.
« Last Edit: August 03, 2008, 09:42:25 PM by jjwaller »

Offline Hush

  • Finally they realise that I am an
  • Really Old Timer ...
  • ******
  • Posts: 6,733
  • "Lady, I've heard it all before"!
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #2 on: August 03, 2008, 09:44:56 PM »
Mine says run bike till normal temperature then shut it down and turn over using large socket.
I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline MrZxp

  • Hot Shot
  • ***
  • Posts: 364
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #3 on: August 04, 2008, 12:05:16 AM »
This from the shop manual...-



And the proper way to do it...   ;D




Cheers, Phil
09 Boulevard M90
SOHC4 Member #3336

Offline Thfireman

  • Full Member
  • **
  • Posts: 28
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #4 on: September 21, 2008, 11:13:32 AM »
Wow,  Thats a vast differnce in technique.  OK, Cool but what happens if you do it while it is at idle?  Just curious if it is damaging to do as the book says, if so they need to do an update. ???

Offline XN

  • Hot Shot
  • ***
  • Posts: 261
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #5 on: September 21, 2008, 09:40:33 PM »
I asked the same question on my K8. All agreed the manual was wrong...
78 Honda CB750K
02 Yamaha V-star 650
02 Honda VTX 1800

Offline MrZxp

  • Hot Shot
  • ***
  • Posts: 364
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #6 on: September 22, 2008, 01:02:02 AM »
OK, Cool but what happens if you do it while it is at idle?  Just curious if it is damaging to do as the book says, if so they need to do an update. ???

Prior to discovering this esteemed website, I attempted to adjust my camchain as per the shop manual.... apart from the extreme difficulty in reaching to the back of the engine while the engine is running (hot!) and not withstanding having to make adjustments with the carbs still in place I would have to say it was a dismal failure and resulted in things sounding much worse and the bike running like cr*p!

Not recommended.  :'(

Cheers, Phil
09 Boulevard M90
SOHC4 Member #3336

Offline KB02

  • Take it easy there, Sonny, I'm an
  • Old Timer
  • ******
  • Posts: 3,736
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #7 on: September 22, 2008, 05:00:02 AM »
Wow,  Thats a vast differnce in technique.  OK, Cool but what happens if you do it while it is at idle?  Just curious if it is damaging to do as the book says, if so they need to do an update. ???

I have never done it the "Right way," and have always used the manual method. I've never noticed much difference in cam chain noise using this method unless the chain was really out of adjustment. The difference being that using the "Right Way" method, the chain is stationary with all the slack on the tensioner side. This way it is easy to adjust out. Using the manual method, the chain is constantly moving, so the bulk of the slack is is moving as well. The odds of your being able to tighten the bolt right at the moment of slack being where you want it is remote.

Question: Why do we tighten the bolt at all? Why not keep full tension on all the time?
« Last Edit: September 22, 2008, 09:49:52 AM by KB02 »
1978 CB750K Project
2000 Ducati Monster
...and a pedal bike

Join the AMA today!!

My project thread Part I: K8 Project "Parts Bike"
My project thread Part II: Finishing (yeah, right) touches on Project "Parts Bike"

Offline Buber

  • A bit of spanner spinner, but definitely not a
  • Hot Shot
  • ***
  • Posts: 394
  • #820 on old mailing list.... :)
    • Mountain Chalets in Polands
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #8 on: September 22, 2008, 05:09:45 AM »
It worked like a charm on my CB650 (twice! I was swapping camshafts) - the "running method", and yes I'm puzzled. I mean, i realize how the things work, so it should be better with the "stationary" method. yet my experience proved (me) otherwise....
Welcome to my mountains!
Mountain Chalets

Offline UnCrash

  • Pass
  • Master
  • *****
  • Posts: 1,694
    • My Blog
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #9 on: September 22, 2008, 06:52:52 AM »
I don't know who wrote those instructions for doing it while running, nor how they got approved for publication.

Always follow the Honda shop manual instructions posted earlier in the thread by MrZxp.  They show you how to find the spot in a chain's rotation when maximum slack exists on the backside (tensioner - side) of the cam chain.

The cam chain tensioner rod can become frozen inside its housing.  I noticed when I bought my 78 750F that the cam chain sounded way loose.  I followed the shop instructions but there was no change.  Thinking that this couldn't be right, I took off the cam chain tensioner and found it to be frozen up.  A little effort and WD40 later it was working great but I questioned the strength of the spring.  I put it back on the bike and followed the procedure for finding 15 degrees past TDC of #1 and pushed the tensioner rod in by hand with an allen wrench while closing the locking screw which holds the tensioner rod in place.

This made a world of difference.

You can't make too much popcorn, but you can definately eat too much popcorn.

Offline gsgleason

  • new to this
  • Full Member
  • **
  • Posts: 91
  • 1975 CB750F
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #10 on: September 26, 2008, 04:27:56 PM »
This from the shop manual...-



And the proper way to do it...   ;D




Cheers, Phil

From what document did this 'correct' way come?  I'd like to give it a read if it's available.  I always thought the factory service/shop manual was always correct.  It's scary to hear otherwise...  Does this apply to all sohc4 engines?  

Also, what is "free" vs "tight", and which is cyl number 1?
« Last Edit: September 26, 2008, 04:34:46 PM by gsgleason »

Offline MrZxp

  • Hot Shot
  • ***
  • Posts: 364
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #11 on: September 27, 2008, 04:17:04 PM »
From what document did this 'correct' way come?  I'd like to give it a read if it's available.  I always thought the factory service/shop manual was always correct.  It's scary to hear otherwise...  Does this apply to all sohc4 engines?  

Also, what is "free" vs "tight", and which is cyl number 1?

I've no idea where this came from... it was recommended as the best way on another thread some time ago. I believe it is applicable to all the SOHC4's. It certainly worked for me.

Cylinder 1 is on the left as you sit on the bike.... when the crank is at T for 1 & 4 the screw/locknuts for #1 valves should be "loose", ie you ought to be able to "wiggle" them - you'll soon know the difference once you give it a try...  ;)

Cheers, Phil
09 Boulevard M90
SOHC4 Member #3336

Offline speedy gonzalais

  • Hot Shot
  • ***
  • Posts: 416
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #12 on: September 27, 2008, 05:30:10 PM »
Mine says run engine untill warm, shut off engine, loosen the bottom locking nut, turn the engine over with a spanner or socket and re-tighten nut at the same time. Before that i was told to loosen nut start engine then re-tighten and gosh did it make the most awfull sound ever , But after trying the manual method it was silent could not hear anything apart from a rattling clutch.
82' C90
87' yamaha T80
79' CB125T/CD200 project
82' CB650z
80s kawasaki ae50/150cc project
92' Suzuki GSXR600
80' CB250N

tenstairs

  • Guest
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #13 on: October 23, 2008, 05:31:16 PM »
There seems to be a link to an article on this topic in the Tech Library (here on SOHC/4.net)

http://www.sohc4.net/images/b/b9/Honda_4-Cylinder_Service.pdf

Would these directions work well?  (See Job #2)

WHALEMAN

  • Guest
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #14 on: October 23, 2008, 09:07:48 PM »
I have always done the static non running method with the engine cold. Does anyone suggest doing it with the engine warm? Dan

Offline Flying J

  • Old Timer
  • ******
  • Posts: 3,372
Re: 78 cb750f cam chain tensioner adjustment confusion
« Reply #15 on: October 26, 2008, 02:03:45 PM »
i have adjusted my chain a few times and there is still some noise. Not excesive noise but still aome noise. Does it ever go away or do these bikes allways have some chain noise?

 

;
Honda