Topic: 750 Cam chain adjuster - Something I think is a good idea

[WHALEMAN]

I have posted about this before but never gone into detail. I believe 50% of the early CB750's have rusted shut cam chain adjuster shafts. I have seen this too many times. Honda left the end of the adjuster casting open. I believe this was so you could see if the shaft was moving or to be able to apply extra force to the chain. The problem is water can enter. If you continuously adjust your cam chain and it still makes noise I would bet yours is seized. To see if yours is seized loosen the lock nut and lock bolt. Stick a small screwdriver tip or any small tube into the open end and turn the crank clockwise and while feeling the shaft reverse and turn the crank backwards. You should feel the shaft move out when you turn backwards as the slack moves to the front. If no movement of the shaft is felt I would bet yours is seized. You can try to spray WD40 or your favorite into the open end hole to free it. If not just pull it off and clean and polish the shaft so it moves freely. While the shaft is out you will see the flat area where the lock bolt hits. It will have an indentation where the bolt has been repeatedly tightened. File this flat as when an indentation is made the lock bolt will try to go back in the dent even though the tensioner would like a little more.After you confirm yours is free and moving or you remove the unit and free, polish and oil the shaft. Now is the time to seal this from water. The outside of the casting is the same size as an old distributor. I take an old spark plug connector rubber and fill the small end with sealer, let dry and just push over the casting. A picture is attached. I believe this problem is more widespread but Mike R could tell us how many seized shafts he finds. Two out of the last three I worked on were seized. Thanks for reading. Dan

[moham]

That's a quality tip there. I'll need to try this on the Ocho because I have not been able to get a discernable difference in cam chain racket after five or more adjustments. This is after all other tuning and a vaccuum sync. Oh, and...ALL HAIL KROIL.

[Alan F.]

Good Idea, I've seen similar protection put over rear axle chain adjusters too.

[kghost]

Yeah I verify movement each time I adjust one ....least one I haven't had apart.

FWI:

The adjuster housing has an oil seal in it.

They do not sell the seal.

I removed the seal on one once because I was going to chrome it......Good news is thier still available from Honda...

point is....don't remove the seal thinking you can buy one....

[andy750]

What seal are you referring to Tim?

 I have a feeling my can chain adjuster on my K4 is not doing its job properly. I have removed it a couple of times but never saw an oil seal? I did however see the notch at the back....so are you saying I should file this down so there is no notch? It looks stock to me??  Do you have a before and after photo of what you mean?

Thanks and good tip!

cheers
Andy

[eurban]

I did however see the notch at the back....so are you saying I should file this down so there is no notch? It looks stock to me?? 

No, he is saying that when you tighten down the set "bolt" that locks the adjuster into position it creates an indentation on the tensioner's metal shaft in the notch area.  With the indentation, the shaft will "want" to find the same spot each time (as you tighten down the set bolt), defeating the self tensioning feature.  He is suggesting that you file out the indentation in the notched area so that the shaft will stay in the correct position even after the bolt is tightened down.  Make sense??

[andy750]

Sure does - thanks for the clarification!

Now what about this oil seal in the adjuster housing? Where is it exactly?

cheers
Andy

[WHALEMAN]

Here are photos of an adjuster that after removing the adjuster bolt the shaft did not move at all. I had to tap it out. The shaft itself does not even seem that rusted but the hole is corroded.  Bad pictures but you can kinda see the indentations on the flat part. Along with polishing the shaft you must roll up a piece of sandpaper and polish the shaft hole. Don't sand the oil seal. Dan

[burmashave]

Thanks for the writeup. I'm fairly certain mine is stuck. I'll have a go at it.

[05c50]

Great tip......and best of all it's all free!

..........Paul

[kghost]

Second picture of whaleman's shows that seal.

[andy750]

Second picture of whaleman's shows that seal.

Got it -thanks to you both!

Cheers
Andy

[WHALEMAN]

Please forgive me. I am bumping this one time as I believe it is a problem a lot of us have. Bob can move to tips whenever he wants. Thanks Dan

[JS550]

Can this be done without messing up any gaskets, & there one between the block & adjuster housing?

[WHALEMAN]

There is a gasket between the adjuster and the cylinder. You can always try to get it loose without pulling it.

Method to Loosen without removing

1. Loosen the adjuster bolt nut.
2. Loosen the adjuster bolt a couple of turns. No need to remove it.
3. The shaft will be about 3/8" back in the open hole on the end. Squirt some WD40 in the open hole.
4. Remove all 4 plugs to make turning the engine easier.
5. The shaft breaks loose pretty easy unless the engine has spent years outside where the shaft might be solid rust. Turn the engine clockwise and then go backwards. Go back and forth. Stick a small screwdriver or bolt in the open end and try to push or tap it. There is no rubber seal here as it is inside the unit. Keep WD40 in the hole. When it does break loose you will know as you turn the crank clockwise and then backwards while feeling the shaft inside the hole you will feel it move. You can push on it as you can not push hard enough to damage anything. Once it breaks loose keep moving the crank clockwise and back while feeling it move.
6. Now adjust the cam chain using the static method of 15% past #1 TDC.
Good Luck, Dan

[JS550]

Thanks.
jim

[JS550]

Ok, its moving, very little. But I would assume thats all it should huh? Seems free & working. thanks again. Great tip.
jim

[BeSeeingYou]

I tried this and could feel the pushrod back a small amount out when I reversed the motor.

[WHALEMAN]

As long as you can feel it move it is not froze up. You will not hurt anything by squirting some WD40 in that end and sealing it up as my first post explains. Glad yours was free. With 2 out of the last 3 I have worked on that were siezed up I am shocked someone has not posted that they found theirs siezed.  Dan

[jaknight]

Thanks WHALEMAN,

Great working-know-how tip here.  Really do appreciate this.

I'm going to check my '74 750 K4 today (after the sun comes up)

~ ~ ~ jaknight ~ ~ ~

[Whaleman]

I am bumping a post I made in 2009 as I feel this is something that is not discussed a lot.

[Big Jay]

You can easily eliminate all the oem tensioner problems. Check here;  http://cbrzone.com/sohc.html

[bjbuchanan]

I poke the tensioner hole with a little screwdriver either way to make sure it isn't stuck. Mine hasn't been stuck yet but still worth the 5 mins it take to move the airbox lower out of the way and poke with the screwdriver. A little insurance can go a long way, no need for fancy stuff here

[Whaleman]

I would like to bump a 5 year old post as I do not see this talked about a lot and in the last 5 years many new members Thank you, Dan

[Whaleman]

I would like to bump a post I made in 2009. This is for new members. I believe Honda could have designed a small treaded cap to keep this area dry and lubed and still allow checking to see if it is moving. These bikes are now 11 years older than when I first posted this so I bet a few more are seized up. Thanks for reading. Dan