Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: exvalvesetdabbler on August 26, 2026, 11:42:22 AM
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I was just wondering if theres a wrong way to dismantle the oil filter bolt. It's one of those aftermarket ones with the larger hex. Been on the bike all the time I have had it. It's on my to do list for the next batch of zinc plating.
It looks like a case of compressing the spring and tapping out the roll pin? Then spending the rest of the day looking for the bits that flew off into a dark corner.
Best regards
Dave
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I'll be watching with interest, I may soon be doing it myself.
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Did exactly same thing on my CX500 oil filter bolt although it went for cerakoting rather than zincing.
Yep, just tap out the roll pin. I just surrounded mine with a rag just in case of mass ejections.
Went back together dead easy also.
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Why??
Just give a good clean, Using a brake/clutch cleaner and polish the head
The rest is hidden
Sent from my SM-A546E using Tapatalk
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Because it wasn’t hidden.
And…… even if it was hidden, I would still do the same.
We all have our ‘isms and some ‘isms may differ from yours.
Apologies for starting a sentence with both Because and And! I will self flagellate later 😬
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There is evidence of some aftermarket oil filter bolts being assembled wrong. I've done a few of the bolts now, it's fairly easy. However getting the insides to slide easily down the tube can take a little doing. I can't remember exactly now how they are supposed to be assembled but lets say it's plug, spring. Some of David Silvers bolts were spring, plug. Meaning they wouldn't work as they were meant to. In fact they wouldn't not work at all. Or they'd be permanently reducing the oil pressure by opening areas not meant to be opened except when the filter blocks. I've also found pressure relief valves on the oil pump itself jammed solid. 3 out of 4 were stuck in place.
It's where I find the little plastic wheels I use on my Dremel come into their own. You can use a really fine grade of wheel to essentially polish the components to allow them to move very freely when needed. Very easy to do with no effort at all.
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Mine was the original Honda type Oddjob. Knowing me, I would have photographed it as I went along (kiss of death that statement eh)
If needed, I can trawl the archives and send on to whoever needs.
Just let me know if required and I’ll check on the comp 👍
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Just found my stash. I have 3 disassembled. Just a cup like plug and a strong spring along with the roll pin. I must have left them dissembled in order to zinc plate the bolt but my illness last year put paid to that. I did however find an oil filter washer in the same box, that made me look around and find an exact copy in stainless steel so I ordered 50. I'm doing a 1976 Kawasaki Z100A1 at the moment for my brother in law, I found that just like Honda they also used the same type of washer to prevent the spring under the filter from going through the rubber grommet in the filter and of course his was missing. I had to make one out of a gearbox thrust washer as they were no longer available even from specialists like Zpower. I think it's spring in first, followed by plug. Then held in place by roll pin. That would mean the plug would be exposed by the filter spring and thus able to be forced back against the oil pressure and so allow openings in the filter bolt being exposed and allowing oil to bypass the filter in the event of a blockage.
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Some of David Silvers bolts were spring, plug. Meaning they wouldn't work as they were meant to. In fact they wouldn't not work at all. Or they'd be permanently reducing the oil pressure by opening areas not meant to be opened except when the filter blocks.
Eeek! Mine is a DSS one too. :o I entered this thread thinking of something else, I've never thought to take a closer look at the bolt but I will now. If it is in right, ok but how to test? I'd rather not be pulling apart, knowing me at best I'll need my big magnet to hunt missing pin, or at worst I'll end up with an eye patch like Long John silver, never mind David Silver. ;D
I think I'd rather take a leaf out of John Webley's book.
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The schematic is correct
The cap is nearest the hex on the bolt, followed by the spring. Both then held in place by the roll pin.
No stress…. easy peasy job to do.
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Yeah that makes sense. For some reason I was thinking the filter went on the bolt first but of course it doesn’t.
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But what does this spring within the bolt actually do, if there is a pin crossing the circle of the spring? What and how to check?
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Its a bypass / pressure relief. If the filter becomes blocked, it moves allowing free flow of unfiltered oil to continue around the engine
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The spring compression rating will allow it to compress at a certain PSI.
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The spring sits on the roll pin, it pushes against a small metal cup, with the spring sitting inside the cup. The cup blocks holes in the filter bolt, however if the filter collapses or blocks enough to stop oil flow the pressure of the oil pushes the cup down against the spring pressure and that means the holes it was blocking are now exposed. The oil uses these holes to bypass the filter so stopping the engine from seizing. Get a small sharply bent piece of metal and push down on the cup, it should move, if it doesn’t you have a problem and you’ll need to dismantle the bolt to free it off.
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The spring sits on the roll pin, it pushes against a small metal cup, with the spring sitting inside the cup. The cup blocks holes in the filter bolt, however if the filter collapses or blocks enough to stop oil flow the pressure of the oil pushes the cup down against the spring pressure and that means the holes it was blocking are now exposed. The oil uses these holes to bypass the filter so stopping the engine from seizing. Get a small sharply bent piece of metal and push down on the cup, it should move, if it doesn’t you have a problem and you’ll need to dismantle the bolt to free it off.
Thanks Oddjob. A better explanation than my simplistic version :-)
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The spring sits on the roll pin, it pushes against a small metal cup, with the spring sitting inside the cup. The cup blocks holes in the filter bolt, however if the filter collapses or blocks enough to stop oil flow the pressure of the oil pushes the cup down against the spring pressure and that means the holes it was blocking are now exposed. The oil uses these holes to bypass the filter so stopping the engine from seizing. Get a small sharply bent piece of metal and push down on the cup, it should move, if it doesn’t you have a problem and you’ll need to dismantle the bolt to free it off.
Thanks for this Odjob, I'll be doing this at my next oil change that is coming up soon. ;)
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I would suggest checking the oil pressure relief valve on the oil pump at the same time George. Not as easy to check though I’m afraid.
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I would suggest checking the oil pressure relief valve on the oil pump at the same time George. Not as easy to check though I’m afraid.
I'm soon to have the seals on my oil pump changed ( got them from Julie) I'll get it done then. Thanx mate! ;D