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Clutch less engine run may eliminate or rule in a possible g/box clutch problem, as would cam cover off for top end...

Clutch basket removal to inspect rear of clutch drum. Check CMSNL for a missing washer but it's been like that since you have had bike.

Have you been attending to cam chain tensioner at all ?
 

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While it's running short out one plug at a time and see if the sound changes(rod knock). Running in gear, with the clutch pulled in, will stop all the transmission parts from turning to rule out noise from there.
 

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1986 Honda Rebel 45
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Discussion Starter · #23 ·
Hey. Yes the clutch basket nut seems tight but again I don’t have a socket yet..
The play in and out is tough to measure.

Top cam chain adjuster bolt tight or loose ?

Top cam chain adjust bolt is definitely tight.

Cb400n and the 450 version ( 250 the same ) are prone to left cylinder big end failure, as it is the last shell bearing to get any oil.
The left cylinder has 145 psi when I did a compression test and right cylinder had 165 I think. Left was definitely 145 though.

No marks on piston crown.



I assume electric start works all ok ?
Yes electric start works perfect
A quick ten second engine run would be sufficient.....possibly ?

The bike makes the noise cold or warm. It seems to dissipate when engine is revved over idle speed.

back to the top under the valve cover. The large wedge seen at the back of the head does not spring down. I was told it’s supposed to. The smaller wedge does however spring down.
I was told to adjust the tension with the 2 bolts behind the cylinder and I did do that
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1986 Honda Rebel 45
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Discussion Starter · #24 ·
I have done that with the spark plugs in and out on each side. The noise is the same taking plug wire off from one side and then the next. The sound stays the same. Clutch in or out the sound is the same. It just disappears above idle. Example: if I was to raise the idle to where you did not hear the knocking and ride it you would not hear the knocking. It’s just at idle speed. That’s what’s driving me nuts. Also to add when starting the bike with plugs out there is no knocking at all. It’s just when bike is running
 

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1986 Honda Rebel 45
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Discussion Starter · #25 ·
I would like to start the bike with the clutch cover off and the valve cover off to see if I can locate the sound but I’m not sure if that is a smart idea or not there will be no oil in the bike and I’m not sure if the oil pump would have to be re-primed starting it without oil in it what do you guys suggest? The self texting does not add. In between sentences sorry for that
 

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Discussion Starter · #26 ·
Well started it for a couple of seconds and still have no Idea where the noise is coming from. This really sucks now. So hard to pin point the noise. Ever with the covers off
 

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No NO NO in BOLD, no, the engine must have oil in it, even for a ten second run. Shell bearings DO NOT like no oil, nore do those rocker arms and many other things !!!!!

More about that later, back in a minute...
 

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Oh well, what's done is done and can't be undone.....

Thanks for the brilliant sharp pictures, 5 pictures, 5000 words, I will be brief...

As Mike says, SHORT OUT plug leads to kill a cylinder.

The ignition system should be considered to be FRAGILE, DO NOT disconnect a plug lead with the engine running !

Are your plug leads yellow and black ? Suggesting a non standard HT coil, no matter.....

Picture 1
DOT. More or less perfect position if already adjusted, auto adjusted by the spring loaded system. Good length of slot left as well.

Do not be tempted to help, over adjust that spring loaded auto adjust system. Over adjustment just wears stuff out quickly. The "slipper A" that sits between the balance chain is vertually unobtainable, it costs an organ. The "rubber" on it will be rock hard by now. Over tight engine chains make a sort of winning whizzing rustling noise, which I have heard in one of your videos when the throttle was blipped.

The dot is in a good position.

Picture 2
Make sure the oil pump chain does not touch that hexagonal tower, the oil pressure relief valve, that lives just under the oil pump sprocket. They very very very rarely stick open due to spring.

Picture 3
Cam area.
Right exhaust valve rocker arm looks a little "dry" and a bit discoloured at the cam end. The valve working clearance adjusting screw looks a bit deep in the valve end of the rocker arm. This suggests a possible lub problem, but that's for later. I suspect the rocker arm can contact pad may he quite worn. I will listen again to the knock.....after finishing this post but do not think this possible problem is your knock.

Check to make sure that the oil pipe is not contacting the camshaft, it looks as if it is quite close.

Pictures of valve springs and view from other side would be good. Do the valve springs have a yellow paint marking at the top, all of them ?

Picture 4
Slotted nut.

See my picture at bottom, these are "stakable nuts" from the car world. Does the slotted clutch nut look like them ?

CMSNL com. Cmx450c rebel 1986 (g) USA California, is this your exact bike ?

Slotted nut, is that a wire clip on that nut ?

No clip is shown on CMSNL exploded views....

The blueish washer under the slotted nut, can I see some writing on it, maybe "outside" it part of that word ??

To me the slotted nut looks as if it's on backwards.....

Picture 5
Cam chain adjuster.....is there a rachet system on the two parts, lines going across from side to side to "rachet" ?

Also, a bright area, maybe steel wire or foriegn object, close to the cam chain adjuster ?

Engine run with cam cover off ( but clutch cover etc. On, oil to level ) This is easily doable but messy. You will see oil flow to camshaft ends. Oil flow should be good and about the same side to side, oh hang on, yours had external oil pipe, will have to check as oil flow may be thru those pipes only, I will come back with oil flow diagram for you.......but engine run and oil flow check easily possible, but Messy !

As Mike says, with clutch all together, clutch cover on and oil to level, in gear with clutch pulled in ( disengaged ), and back brake on, all gearbox and clutch hub will stop turning, but, the clutch basket will still be turning cos the crank is cos the engine is running.

Feedback.....

I will listen again to the knock vidio...

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1986 Honda Rebel 45
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Discussion Starter · #29 ·
Thank you for all that info. A closer inspection of the brand new oil I just drained out shows metal flakes. A lot of them so I think it’s time to seak professional help and or give up on it and sell it. I have a couple of motorcycle mechanics at work that may be able to rebuild the engine but than again I paid 1500 for the bike. Don’t even know what they would charge me.
i did run the bike with the covers off only to find I still cannot locate where it’s coming from. Also the oil light and neutral light does not illuminate at all anymore since running it without the covers. Feeling way beyond defeated right now. Not happy at all. Have to think of what to do now. Not sure if it’s a top end piston problem/ low end crank shaft problem/ or oil system not working correctly. Would hate to pay to have a engine rebuild and not have the oil system not up to par and repeat the whole process over again with lack of lubrication. I don’t know. I really don’t know at this point. I’ve tried what I can. I think myself digging into the engine with limited knowledge of these engines and lack of information from a online manual is a no go for me. This is the oil I drained out before I pulled the clutch cover off. It was brand new oil and the oil pan was very clean before I drained the oil.

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Glitter.....

Close and lock your workshop door, go home, gave a beer, a good night's sleep.

Tomorrow is a new day.

You have a good looking workshop with a good amount of room.

These engines are not that complicated. A few tools needed like clutch nut peg spanner/socket which you could make, there is a thread on here about that, and a flywheel puller bolt.

What have you got to loose by taking this engine apart.

CMSNL views are very usefull, I am sure there will be manuals out there.....you can do it.

Anyways, enough for today, go have a beer or two, but not 3.
 

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Drag a magnet through that oil, see what it picks up. Bearing shell material is non ferrous(non magnetic) steel particles will adhere to the magnet.
 

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Discussion Starter · #33 ·
Update to the one problem of the oil light and neutral light not illuminating. Both bulbs have blown out. I verified that with a good bulb into the oil and neutral sockets. Oil light goes off when engine is started so that crisis has been avoided. That makes me feel better. Engine still with problem makes me feel worse 😩😂. Atleast I know that there is oil pressure !
 

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That's correct, at least the oil pump is creating enough pressure to turn the light off, but how much pressure after that and when the oil is hot, and does the oil pressure relief valve work properly, and does the oil filter by pass work properly, and a few other oil system "functions".....

Is the clutch cover still off ?

CMSNL cmx460c rebel 1986 ( g) USA California, your bike ?

Exploded views show a proper sump and oil filter underneath the engine, at the front. If the sump has sufficient oil in it, just so it starts to dribble out from by the oil pump chain with the bike on level ground and on the centre stand, it is safe ( safe ?????? but lots of dangerous rotating gears, chain, clutch drum, when engine running !!! ) to run the engine oil wise, as the oil pick up pipe and filter is quite well submerged in oil.

If you did this, you could see if the oil pressure relief valve leaks, and opens at high pressure, about 70 psi.

Also view oil flow to head and cam and the rockers. Remember I said I suspect that dry looking discoloured right exhaust valve rocker arm being quite worn....

Remember with engine running, cam cover off, clutch cover off, a real oily mess will result, a real oily mess !!!!!

Anyways, have you checked behind clutch basket so parts touching, banging, knocking ?

There is quite a bit of play/slack in clutch basket both in and out, play with the damping springs.....

I would like you to do the following...

Engine off, plugs out, working from flywheel side, turn flywheel in normal direction until flywheel side goes over tdc with piston half way down the bore in one steady slow movement. This places the piston and con rod in the "power" region of its movement ish. This is the position where the big end would be most worn ish.

Any play would leave the piston "up", in relation to the crank.

Looking at the piston crown, and moving the crank backwards, does the crank move backwards with no piston movement at all, and any "clunk" heard, as if big end play has been "taken up".


Do this test many times, say ten times.

Any "play movement" seen or clunk heard ???

You say compression not so good flywheel side.


Feedback feedback feedback.

Two of my books have gone AWOL over Xmas, still not found them, want to check oil flow diagram....

Over.....

Dd23
 

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Discussion Starter · #35 ·
i will try some of your suggestions tomorrow. I put the clutch cover back on and filled with oil. Not many videos at all on YouTube about this rebel 450 engine. Was wondering what the closest engine would be to it. Maybe I can find more videos on those? I think the cm400 engine is close. Are there any others. I see the cb engines are different.
 

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Discussion Starter · #36 ·
DD I tried what you said but no I don’t hear any knocking or any weird noise. I’m only able to look through the small piston hole though. The cylinder head is not off. I’m just probling the top of the piston with a long screw driving trying to see if it moves or not. But no I don’t hear anything weird.
 

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So, piston set as described, crank moved backwards slightly, piston moves up instantly as seen thru plug hole and no "clunk" heard as if play in the big end has been taken up ?

Good.

A slight variation next, turn crank in normal direction, watch piston go over tdc and go about half way down the cylinder. Push down on piston crown with some wood dowel, or your probe.

Any piston downwards movement with no crank movement when piston is pushed down, any clunk heard as if play has just been taken up ??

I hope that answer is no clunk and no downward piston movement with no crank movement.

Further downward pushing of the piston crown results in crank movement.

This is a very rough and ready "measurement" of big end play but there still may be a bearing problem.

Feedback
 

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Discussion Starter · #38 ·
In the middle of this testing I was able to muffle the exhaust and get a better listen. The sound is pretty much the same from bottom of the engine to the stop of the cylinder cover

 

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Ok, listened and watched your last vidio.

Are you sure there is no exhaust leak at all ?

If there is a slight leak, it is not the knock.

Do you have a strobe timing light and some tippex white correction fluid for typists ?

Mark in tippex the flywheel T so it's is really easy to see.

Use strobe at engine idle. It should be possible to identify where the tippex mark is when the knock occurs, a datum if you will.

Ben took a brilliant vidio of his engine noise, managing to slow the vidio play back down, but didn't explore that "info" further.

Establish where the tippex mark is when the strobe flashes and noise heard.

Even slow down the idle speed to help

Do you have a test tank, or, allow carbs to fill with fuel. Remove tank and cam cover. Start engine and watch the top of the cam chain adjuster. Anything happen ?

During this run is there good oil flow to the right side ?

That suspected badly worn rocker arm pad on the right exhaust valve may be noisey.

Do you say the engine knock was noisey more at the bottom of the engine ?

A vidio if the cam area particularly that right exhaust rocker please...

Feedback

Over....
 
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