Topic: 78 cb750f cam chain tensioner adjustment confusion

[dboblet]

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???

[jjwaller]

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.

[Hush]

Mine says run bike till normal temperature then shut it down and turn over using large socket.

[MrZxp]

This from the shop manual...-



And the proper way to do it...   




Cheers, Phil

[Thfireman]

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.

[XN]

I asked the same question on my K8. All agreed the manual was wrong...

[MrZxp]

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

[KB02]

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?

[Buber]

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....

[UnCrash]

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.

[gsgleason]

This from the shop manual...-



And the proper way to do it...   




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?

[MrZxp]

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

[speedy gonzalais]

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.

[tenstairs]

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]

I have always done the static non running method with the engine cold. Does anyone suggest doing it with the engine warm? Dan

[Flying J]

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?