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Messages - Erwin83

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1
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: August 28, 2022, 02:54:30 PM »
I retorqued the headnuts and placed one extra ring under the one nut that I found 'loose' again. Idea was that maybe the tread on the one with the most elasticity was not perfect and the extra nut ensures the use of cleaner thread. Or if the nut bottomed out, the extra ring gives more space and makes sure the nut clamps down on the head for sure.
In any case, the elasticity is now gone...

I have not taken the head off. Just retorqued with the head in place.

2
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: August 28, 2022, 07:38:38 AM »
Runs fine now, have not seen even a puff of smoke.

https://youtube.com/shorts/v9xFpDdq0PY?feature=share

3
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 20, 2022, 10:45:13 AM »
At the risk of sounding daft I have felt this sensation decades ago when tightening Helicoiled threads back in the early days of Helicoils.

Are all the head stud threads in the block as per original ?

Yes, the studs have never been removed from this block. Also did not come loose accidentily when undoing the head.


A question to the OP, can you turn the nuts with your fingers when they are not torqued/tightened ? In other words can you twist them down with your fingers easily until they touch the washer and then just needing to be tightened with a socket from there ?

Thinking we may have interpreted the description of "elasticity" wrongly. If they are tight right from putting the nut on the stud then that will give a torque requirement without even clamping the head sufficiently to start with.

Thinking out loud really as they should stay tight once assembled with no real problem. 

Are they the original nuts that are in use too ?

Yes, I'm using original nuts, although I may have mixed up some 350 / 400 parts as I have been working on both these engines simultaneously for years.
All the nuts go on smoothly. I normally use a long socket to place the nuts and reduce the chance of the nuts falling in. They all feel normal when turning them the first couple windings with my fingers on the socket.

4
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 20, 2022, 10:40:27 AM »
At the risk of sounding daft I have felt this sensation decades ago when tightening Helicoiled threads back in the early days of Helicoils.

Are all the head stud threads in the block as per original ?

OK, I did not think of that before. I'm using Bell Ray EXL 10w40 (mineral). Should I move to another oil type?
I was not planning on putting on oil cooler on this bike to be honest...

5
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 08, 2022, 07:48:34 AM »
Took the valve cover off last night and found that the 2 nuts on the intake side of cil 2 (the smoking cilinder) were indeed a bit loose again.
I've tightened them up, but one would not stop with the 'elastic' feel once torqued. So I added another ring and that helped (for the feeling of stretch at least). Maybe this nut is binding on the threads or binding in the dome of the nut?
No idea, but I'll put everything back together this weekend and see what happens.

6
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 07, 2022, 10:20:49 AM »
Well I'm hopefull it's not that. Afterall, replacing the headgasket and (re)torquing the head nuts stops the smoking completely.
It appears to come back only after riding hard (full throttle up to red-line).

I think my issue is with the studs/nuts, as I have this 'elasticity' on torqueing, and headnuts that appear to come loose after a short while of riding (couple 100 km).

7
CB350/400 / Re: 400 - “elasticity” in headnuts
« on: July 07, 2022, 09:33:46 AM »
So, couple months (and just a few kilometers, really) later. I'm back at square one.
Again, Cilinder 2 is smokey. I started riding, nice and easy. No smoke. Once everything was nice and up to temp I gave the ol'girl the beans and cilinder 2 (I have a non-balanced 4-4 exhaust, so easy to diagnose) started smoking again. Looks like head gasket again.

I'm going to retorque the head again, first without changing the gasket. Remember last time I found 'loose' head nuts.
Could there be anything wrong with my Studs, or Head?
Is there any harm in using an extra ring under the head nuts, just to make sure the nuts are not bottoming out on the studs (because of the aforementioned elasticity)?

8
Project Board / Re: CB466f
« on: June 03, 2022, 08:30:21 AM »
Finally some time to ride, and after all the work I can confirm... She is finally free of any oil leaks. I guess this is the first time in 19 years of ownership she has not been leaking any oil  ;D.

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9
Reading this article: https://s3.amazonaws.com/sohc4-articles/CB400/Improving_the_CB400F_camchain.pdf
It seems that there actually should be a whine with the chain at normal tension. So I think I'm good.
Again, I've never had a proper tight cam chain in the last 19 years. ;D

10
Ran the bike at 2000 rpm steadily and released the bolt that stops the tensioner. I can hear that with the bolt undone, the sound changes (tensioner moves) and once I tighten the bolt back down, the sound disappears again.
However, the humming noise while riding has not disappeared.
So, I decided to just take it as it is, and give 'er the beans.

Ride for >30 minutes, oil nice and hot. Sound does not change. Bike runs great.. It is what it is.

11
Come to think of it, I did actually tighten the chain static, with an eye on the chain, rotating the engine to bring the chain in a position where all slack was on the tensioner side. And I could actually see it spring to tension when releasing the rod.
Maybe I should redo the procedure according to the manual, with engine running...

I'll go and try that  :)

12
Can it be too tight? It’s purely spring loaded right? I have not pushed on the rod or anything, just release the clamping bolt and tighten again.

13
Hi everyone
Last year I finally bit the bullet and opened my 400/4 cases as I had the dreaded hairline crack in the bottom half. Got that welded.
As a “while I am there”, I also changed out the cam chain tensioner for the CNC version with bearing.
So now, starting to ride my CB again this spring, in the first time in 18 years of ownership, I have no more oil leaks and a properly tensioned Cam chain!

So much so, that I have to get used to the engine noise all over again. And I hate mechanical noises I cannot exactly identify...
I have a slight humming/whining noise that I think is the chain going over de guides. Do you recognise this change in sound after installing the upgraded tensioner? Bike runs good across the complete rev range.

14
CB350/400 / Re: A tappet mystery
« on: September 02, 2021, 04:16:29 PM »
Sounds like you have tried to set the valve clearance while the cam was keeping the valve open, and how the clearance is way (WAY) too large.
You can only set valve clearance (tappet adjustment) when the cam is pointing away from the valve, you have to rotate the engine in order to get to that point for each valve.

15
Sounds about right  ;D. An often forgotten piece of advice is to wear comfortable shoes. The walking distance on jobs like these is not to be underestimated.

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