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Discussion Starter #1
Okay, I got your attention, because my question, more accurately, is "How robust is the bottom end on the 650?"

Theoretically, if someone bought a decently maintained, low mileage 650, why not just put an aftermarket inline oil filter on it and call it a day (as far as the bottom end is concerned)?

I was watching that lowbrow customs 650 rebuild video series and the bottom end on that bike was more less perfect. Of course a high mileage bike that was not maintained will have a sludge trap that need attention, but it seems like if the bottom is 'so far so good', why not just begin filtering the oil and stop the trap from continuing the accumulate sludge?
 

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Hi, so here's my twopenoth, obviously with caveats, if you're tearing the engine apart clean the trap (why wouldn't you?), if not fitting an aftermarket filter is a good idea anyway.
I'm running a norton filter on my 68 trophy. There's a plan for fitting this to older trumpets........I've got it somewhere if you're interested......with specs for machining a clamp that fits it on the rear downtime, just below the swingarm......works pretty good. I had a local machinist do the work, well spent $50.
 

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did i read somewhere that modern oils could soften any deposits in the sludge trap and release particles into the oil ? -- might have been a dream / nightmare after imbibing of the water of life --- i always strip my motors to clean the sludge trap -- never had one yet that made me say ---" by jove thats sparkley clean - no work needed - i do so wish i hadnt stripped the motor" ---- (or maybe the lockdown is beginning to affect me !)
 

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I use Rislone in my oil, and I have a Charlie’s filter with two filter elements stacked inside the frame. The Rislone will definitely dissolve deposits, I have seen it work miracles on old engines. I believe even the sludge trap Will be cleaned and I have confidence the filters will do their job.
No way would I pull a motor down just to see what the sludge trap looked like. I can watch the oil flow, so it isn’t clogged, and I don’t believe it’s going to become clogged.
 

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Hi All, The sludge trap is a centrifugal filter so anything that is heavy enough in oil will separate & ultimately cling to trap which is the interior of tube facing the outside. Over time the sludge becomes very hard like a hard clay.

My observation has been modern oil will not wash it out or dissolve it during operation because there is not really oil flow in that area. The point was to make a "still" area where sludge could collect. I've seen Triumphs run several thousands of miles with modern oil & trap was still full. Sludge are hard as ever. Of course oil filter will reduce filling of trap by catching particles that would have ended up in trap, but I've not seen it clean trap.

My observation with car motors over 50 years, moving oil in passages don't accumulate sludge. It's the still areas that do, no matter modern oil Old varnish is another issue. It is not sludge per se.

You cannot tell by oil flow if trap is full & blocking oil flow visually by watching oil return. The pump puts out it's volume the same no matter the trap condition. Oil will come out pressure relief valve that doesn't go through crank.

Hypothetically oil pressure would be higher with clogged sludge trap, but so many variables for pressure I don't think that is practical. At the same time, lack of oil would soon damage rod bearings.

I don't know if when sludge trap is full if it actually blocks oil, or if the moving oil keeps passage way open as moving oil won't allow sludge to settle.

Has anyone ever seen a sludge trap blocked such it starved rod bearing of oil? I mean everything else, oil pump, relief valve was perfect? The failure could be traced to blocked oil passage due to full trap?

Personally I've not done motor tear down on bike long in storage or purchase with unknown history to check sludge trap. Just haven't observed that being necessary.

Anytime crank is out for overhaul or repairs, it is foolish to not clean sludge trap unless you can verify it was recently done & there is no reason to expect it could be contaminated/dirty now.

With proper tools, some home made, proper procedures followed, cleaning sludge trap is not difficult. Unless parts were damaged prior, usually can reuse parts.

In my opinion the bottom end is robust & trouble free. Rod bearings last a really long time. Other things ruin crank. Dirty oil, poor oil pump, poor pressure relief valve. Too high of RPM.
Don
 

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At 40,000 miles, my sludge trap was half full. It was solid material which needed chipping away with a tool to break it up. i would agree that if the engine is apart, it should be cleared, but if i had a 10,000 mile engine, i would leave it to run but with an external oil filter. I had been running modern oils with no oil filter and i would not think that oil was lifting the sludge out at all.
 

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Going from one country to another on my old "special" R75 / K750 I experienced crank seizure caused by nearly complete blockage of oil drilling in a crank caused by sludge overflowing BMW type centrifugal filter.
It happened 45 years ago, but it's still quite vivid in my memory.:)
 

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Discussion Starter #11
Thanks for all the replies. Made for some good discussion.

My opinion is: I wouldn't bother tearing down a "lowish" miles, fairly well taken care of engine to check or clean the trap, especially if I were fitting a filter on it. But of course, if it is coming apart for some other reason, I definitely would.
 

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Thanks for all the replies. Made for some good discussion.

My opinion is: I wouldn't bother tearing down a "lowish" miles, fairly well taken care of engine to check or clean the trap, especially if I were fitting a filter on it. But of course, if it is coming apart for some other reason, I definitely would.
I bought a '73 Bonneville about 7 years ago with 16,000 miles showing. It's a US small tank model and had just been brought out to Australia from British Colombia, Canada. Bottom end seemed fine and is still fine 10,000 additional miles later, all I did was install a Norton type oil filter, I have no qualms about this, if and when I pull the bottom end apart will the sludge trap be done...
 

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I thought I saw a post here somewhere somebody said they never heard of anybody tearing down a 650 just to check the sludge trap. Well, here I am, I’m tearing my otherwise beautiful condition 650 down to the crank mainly to see what is in there and clean it out. I also am hooking up a pressure side filter and then I will run detergent oils which would melt down anything in there so I don’t want that cruising through my bearings. Plus it is old, the last time I had it apart was 40 years ago and I don’t think it has ever been opened up. ( sludge trap that is ) I know I didn’t know about the trap the last time and didn’t do anything with it. I was pretty young then and fresh to Triumphs , now I’m pretty old like it is.



I invite anybody with any doubts on the matter to view “ Dave’s ( Caulky ) ‘74 T120V Rebuild “ on this forum and see pictures of an entirely plugged up sludge trap. ( I think it caused the destruction of his motor)
 

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23, would you update us on your progress? I'd love to know the details on your motor and the condition of your sludge trap after 40yrs.
 

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I have always wondered why anyone would design an engine to trap debris where it would clog oil passages and destroy the engine. Totally hidden and not serviceable without a complete engine tear down, too. The logic of doing something like that versus draining debris with the oil totally escapes me.
 

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I would expect flowing oil in the crank passages under pressure would never allow the passage to plug and stop flow, even when the sludge trap got full. I have seen Rislone do miraculous things on sludged engines over the years. My belief is that if the dirt can be held in suspension and drained vs. being stored in the crank you are much better off.
 

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I have always wondered why anyone would design an engine to trap debris where it would clog oil passages and destroy the engine. Totally hidden and not serviceable without a complete engine tear down, too. The logic of doing something like that versus draining debris with the oil totally escapes me.
It does sound ridiculous but it is 50 yr old technology filters were metal gauze then.the sludge trap is a tube inside the crank shaft oil gallery, pressure feed from the oil pump and exiting through a tiny hole to the big end shells. It takes a lot off **** to fill the tube but if it does it will take the bottom end out off your motor big time,( been there). Don’t run modern detergent oils unless the tube is spotless and you’ve fitted a remote filter in the return line.
 

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Hi Ccw33, I'm most interested in your experience with clogged trap. I've never seen fully clogged trap. Some say it can't clog, others report it has. Such as your report. So I'm most curious as to how one would determine if it was clogged enough to starve rods of oil.

What did bike do? Meaning you were riding & it seized a rod bearing or something like that?

Both rods or just one?

Did you attempt to blow compressed air through crank or pump oil through it before removing trap?

What I mean is how did you determine oil feed to rod was blocked?

Do you have any idea at all about how many miles was on motor when it clogged?
Thanks, Don
 

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Ccw33 said:
It does sound ridiculous but it is 50 yr old technology filters were metal gauze then.the sludge trap is a tube inside the crank shaft oil gallery
By the time Triumph introduced the tube in the crankshaft, real oil filters were mainstream in cars and AJS/Matchless, Enfield, Velocette, Vincent and even BSA were using a felt oil filter.

Yes I know AMC and BSA actually stopped using the filter, around the mid-1950s!
 
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