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Author Topic: 1974 CB360 Engine Troubles (I think)  (Read 2527 times)

Offline rsjudka

  • Posts: 41
Re: 1974 CB360 Engine Troubles (I think)
« Reply #15 on: May 14, 2017, 01:43:23 »
Yeah I read about the cam chain guide recall, thankfully my bike has that punch  ;D

Thanks for the tip about the compression test.

I won't have any time this week to work on the bike (starting an internship :) ), but as soon as the weekend comes I'll get on it 8)

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #16 on: May 14, 2017, 08:55:14 »
The best way to do a compression test on 360 w CV carbs is pulling the carbs off.   

Im sure youve read plenty about the top end oiling issues.  You could also pick up a tube of 3-bond.  You will need it to re-seal the head cover, when you change out the leaky cam shaft seal behind the points and advancer.  Since you have that seal you could dig into that and take a peek at your cam and tappet surfaces to ensure its not eaten up by running dry.
When you install the oil seal be sure to lube it up pretty good.  If rubber oil seals are installed dry.  The friction caused by the rotating parts will instantly burn the sealing edges and it will leak again.
DTT member, "Sonreir" sells the 3 bond at sparckmoto.com

The workshop manual explains how to remove and re-install the head cover in good detail.
 
Keep us up to date w some pics.
good luck.

Offline rsjudka

  • Posts: 41
Re: 1974 CB360 Engine Troubles (I think)
« Reply #17 on: May 26, 2017, 21:57:31 »
Sorry everyone I've been really busy with finals and work and life and haven't really been able to work on the bike until today.

I was able to do the compression test, and sadly my bike is at 70 psi on both right and left cylinders :( After adding the oil the readings go up to 85~90psi on both sides. Is this a big enough of a change to show worn rings/cylinders? How low is too low of a reading?

Also, not sure if this affects anything, but I bought the bike with aftermarket mufflers, they look like 16" shorties. Would this affect the compression test?

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #18 on: May 27, 2017, 14:43:45 »
No shorties wont affect readings.  Did you have the carbs off the engine?  If not pull them off and re-test.
Then go through and adjust valves.  Honda manual will tell you how to adj valves.  Valves will be the only adjustment you make w a cold engine.
Then re-test.  And report back.
« Last Edit: May 27, 2017, 14:45:36 by trek97 »

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #19 on: May 27, 2017, 14:46:53 »
The engine wont run if its lower than 90 give or take.

Offline Sonreir™

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #20 on: May 28, 2017, 17:05:10 »
Carbs were off the bike when the test was done?
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Offline rsjudka

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #21 on: May 29, 2017, 20:35:28 »
Okay so I did some more compression tests today, both with carbs on and off.

With carbs on, compression on both sides was 70 psi.
With carbs off, compression on the left side was 80 psi and on the right side was 70 psi.

I'm a little confused about the readings because I'm able to ride the bike without any problems (besides the smoke and ticking) so what could be causing such low compression?

So I just got done doing the cam chain adjustment, and am waiting for the bike to cool down. Hopefully I can do it by tonight.

Should I retest compression after the valve adjustment?

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #22 on: May 29, 2017, 23:07:28 »
Yes re-test after valve adjustment.  And BTW adjusting valves on a 360 is not fun.   :P

Post a pic of your compression tester.  Does it screw into the spark plug hole w an o-ring on it?

Are you turning the enigne over several times until the gauge needle wont climb any higher?

Pull spark plugs out of both sides when doing test to let engine turn over easier.
« Last Edit: May 29, 2017, 23:13:52 by trek97 »

Offline rsjudka

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #23 on: May 31, 2017, 02:47:36 »


So this is the compression tester I'm using, the only difficulty I've found is that the adapter doesn't screw all the way into the spark plug hole, but I haven't felt any air leaks while doing the test. I have also been doing it with both spark plugs out and turn the engine over for about 10 seconds, carbs off.

What I did find when taking the valve covers off, is that the left intake valve adjustment screw is missing >:(




 I'm going to try to get a magnet pickup tool and try to fish the screw out. Is this something that could have been causing all my issues?
« Last Edit: May 31, 2017, 22:24:33 by rsjudka »

Offline irk miller

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #24 on: May 31, 2017, 08:38:26 »
You're pics are missing links for me, so I can't see anything, but you should have the compression gauge in one plug hole while a plug is still in the other.  Maybe it doesn't matter, since the cylinders are separate.  But, having a missing tappet screw will be an issue too.  The valves need to be open to suck in air, and you need to suck in air to get compression.  Missing tappet screw on the intake side means no air is coming in. 

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #25 on: May 31, 2017, 20:43:34 »
+1
I cant see pics either.
The threads on your adapter may not be correct pitch.  Just dont try to force it and mess up plug hole threads. Compare adapter to the plug threads.  The difference may be miniscule.

 Or a plug may have been crossthreaded into the hole at some point in the past.  :P

And yes you must find, install and adjust the tappet screw and lock nut.  Fingers crossed it didnt jack anything up while bouncing around in there.
Intake or exhaust screw?  Im with Irk and assuming intake.  If it were exhaust it would build pressure, unless its fucked up.

Just crank it til pressure maxs out on gauge.
« Last Edit: May 31, 2017, 20:49:08 by trek97 »

Offline rsjudka

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #26 on: May 31, 2017, 22:33:27 »
So I updated my image links, sorry about that.

If I do have the wrong adapters (the one I'm using is the M12 which I read is the same size as the spark plugs), is there any place I can get the correct adapters?

Offline irk miller

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #27 on: May 31, 2017, 22:48:21 »
Adapters should be right and fine as long as you're threading to the o ring.  Regardless, with no tappet screw you're not going to get compression.  That valve has to be able to open for the motor to suck in the air that gets compressed.  By the looks of that cover, you've had something bouncing around pretty violently in there.  Might be time to pull the cover and fully assess the damage.  Maybe even pull the head and see what kind of shape the valve seats are in.

Offline trek97

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #28 on: May 31, 2017, 23:09:47 »
Adapters should be right and fine as long as you're threading to the o ring.  Regardless, with no tappet screw you're not going to get compression.  That valve has to be able to open for the motor to suck in the air that gets compressed.  By the looks of that cover, you've had something bouncing around pretty violently in there.  Might be time to pull the cover and fully assess the damage.  Maybe even pull the head and see what kind of shape the valve seats are in.

YUP.

Offline teazer

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Re: 1974 CB360 Engine Troubles (I think)
« Reply #29 on: May 31, 2017, 23:28:21 »
First get a valve adjusting screw and locknut in there and set the valve clearances  on all 4.

Next: borrow a compression tester from an Auto supply store and retest compression.  Turn it over until teh needle stops rising - maybe 5-10 kicks/seconds on starter button.

Chinese compression testers have a nasty habit of reading low by a long way.  I had one that finally read 30 psi on any cylinder...

The gouges in that tappet cover are from the nut and adjuster screw IMHO.  You need to find them if you have not already done so.  They cannot be left inside in the blind hope that they don't get lose.