Author Topic: First attemtp at cam chain tension cb750 k4  (Read 4727 times)

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Offline myoldcb200

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First attemtp at cam chain tension cb750 k4
« on: July 15, 2011, 03:06:09 pm »
Ive read this darn thing and its just not sinking in. 15degree atdc? Why cant they just say turn it 1/8th of a turn after tdc or something like that? I mean that's all your doing is turning it.  I guess its your lvl of math thing idk. My math sucks.  ::)

|t|f| 1|4 

Just to clarify this because the pictures I c seem to point to the | just before the t. When something says tdc do I not want it pointing to the center of T itself and not one of the |s? Same as for the F its not the | before the F nor the | after the F its dead center F isn't it?

And this thing has 2 nuts on it and non of the pictures in the manual tell me this or point to them and say this is this and that is that. Didn't they realize that us primordials would be working on them?  Its speaks of the cam chain tensionor locknut and the setting screw. Do I loosen both of those after this 15degree thingy? Just loosen then tighten and that's that like a 5 second process? Is it that simple and in my newbeish state am making it more complicated?

And I've read and read about adjusting the tappets. Anyone know of a good video on youtube or someplace that I can watch someone do it before I attempt that? Doesn't seem to matter how much I have read on this stuff. Watching it done is way better then reading about it no matter what it is.  :-[
The bike I am working on is --->1974 cb750 k4

Offline Spanner 1

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Re: First attemtp at cam chain tension cb750 k4
« Reply #1 on: July 15, 2011, 05:07:59 pm »
O.K.... I'll try this !
 3 easy steps to follow to adjust your cam chain tension.....
1.   Unscrew the two inspection covers ( 17mm wrench ) over the #1 cyl. tappets and rotate the crank until the 1-4 'T' mark is visable in the timing plate 'window'. Try to move the tappets, if they will move freely side/upwards your ready for the next step. If tight against the valve springs, then rotate 1 full turn until 1-4 'T' mark comes around again.
 
2. Continue to turn the crank slowly clockwise from the above 'T' mark until the round spring post is centered in the 'window' ( you will see the end of the spring wrapped around it ). Stop turning here !

3. Loosen the tensioner bolt ( 10mm head ) and it's locknut 3 or 4 turns. Tighten the bolt and 'snug-up' the locknut .

Mr. Honda says that your camchain is at it's loosest when the crank is turned 15% past the top of the pistons travel after the compression stroke. At 15% past TDC, it just happens to be where you can see that spring post in the 'window'.
When you loosen the 10mm (head) bolt , the spring on the tensioner automatically 'shoots' the tensioner shoe forward to take-up any slack in the chain and re-tightening the bolt sets it in its new position... got it  ;)
« Last Edit: July 15, 2011, 05:11:39 pm by Spanner 1 »
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Offline Really?

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Re: First attemtp at cam chain tension cb750 k4
« Reply #2 on: July 15, 2011, 10:39:22 pm »
I was there not too long ago.  If what Spanner said does not do it for you, check out the two threads below.  I couldn't wrap my head around it either,

http://forums.sohc4.net/index.php?topic=27593.0
http://forums.sohc4.net/index.php?topic=85421 
I don't have a motorcycle, sold it ('85 Yamaha Venture Royale).  Haven't had a CB750 for over 40 years.

The Wife's Bike - 750K5
The Kid's Bike - 750K3

Offline myoldcb200

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Re: First attemtp at cam chain tension cb750 k4
« Reply #3 on: July 16, 2011, 07:41:52 am »
Did as suggested. The post for the spring is nearly rite on the 1/4 mark. :sucks you cant see anything happen for confirmation. That is going to drive me crazy till I fully understand it i guess, but for now I will take your word that I did it correctly.  ::) ??? ;D
 The bike has sat for so long my biggest worry is that that thing is gummed up and it isn't doing anything.

Now how bout those tappits? Any videos on those or a decent read that goes in baby steps?
The bike I am working on is --->1974 cb750 k4

Offline myoldcb200

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Re: First attemtp at cam chain tension cb750 k4
« Reply #4 on: August 02, 2011, 05:15:22 pm »
I took the carbs off and cleaned that one again. Checked the float lvl just be sure (its set at 26mm from the indent on the side of the carb just above the true lvl of where the bowl sits if thats wrong please chime in cuz i am not for sure for sure :D ) And it does have spark. But when I hooked the carbs back up I can now hold the pipe with my hand at least before it was getting somewhat hot but then again that could of just been from the engine running. Idk. Guess I will take the carbs off again and triple check after all I did originally try to start it with no ground at all and got baffled by that.
Any input or help would be great Ive got lots of time because I cant find the title and its now gong to take me forever to plate it.
The bike I am working on is --->1974 cb750 k4

bollingball

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Re: First attemtp at cam chain tension cb750 k4
« Reply #5 on: August 02, 2011, 10:21:24 pm »
Myold here is a pic of what is inside the cam tentioner.

Offline Davidov

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Re: First attemtp at cam chain tension cb750 k4
« Reply #6 on: August 22, 2011, 08:33:26 am »
I'm a little confused now.

The original owners manual instructs to adjust the cam chain tensioner with the engine running at idle (~1000RPM)??

I tried this method, and it didnt really seem to do any adjusting. Now I have some engine rattle on take off?
This is a 78 CB750F I am referring to.
-David

Offline deafcaferacer

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Re: First attemtp at cam chain tension cb750 k4
« Reply #7 on: April 28, 2014, 06:14:51 am »
bump
'73 CB750k engine, hubs, and a '76 tank, on 'a 78 frame. Go figure.

Offline Davidov

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Re: First attemtp at cam chain tension cb750 k4
« Reply #8 on: April 28, 2014, 12:06:47 pm »
bump
Bump on a 3 year old thread? That's ok, I realized my question had been answered.
Don't adjust it with the engine running (even though the manual says to). The static adjustment makes much more sense.

 3 easy steps to follow to adjust your cam chain tension.....
1.   Unscrew the two inspection covers ( 17mm wrench ) over the #1 cyl. tappets and rotate the crank until the 1-4 'T' mark is visable in the timing plate 'window'. Try to move the tappets, if they will move freely side/upwards your ready for the next step. If tight against the valve springs, then rotate 1 full turn until 1-4 'T' mark comes around again.
 
2. Continue to turn the crank slowly clockwise from the above 'T' mark until the round spring post is centered in the 'window' ( you will see the end of the spring wrapped around it ). Stop turning here !

3. Loosen the tensioner bolt ( 10mm head ) and it's locknut 3 or 4 turns. Tighten the bolt and 'snug-up' the locknut .

Mr. Honda says that your camchain is at it's loosest when the crank is turned 15% past the top of the pistons travel after the compression stroke. At 15% past TDC, it just happens to be where you can see that spring post in the 'window'.
When you loosen the 10mm (head) bolt , the spring on the tensioner automatically 'shoots' the tensioner shoe forward to take-up any slack in the chain and re-tightening the bolt sets it in its new position... got it  ;)

-David