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Discussion Starter #1
I'm still fairly new to this motorcycle and Brit bikes in general so if this is a dumb question let me know.

Short backstory, I bought the bike, a 1976 Bonneville a little over a year ago. It wasn't running. I've gone through it, replaced worn bits and got it up and running. Recently had the breather tube come off at the "T" just below the battery, sprayed lots of oil and generally made a mess. I noticed it by the low oil pressure light coming on at higher and higher RPMs. I filled it back up with what was in the garage, 10W30 dino. A week later the clutch stuck. No amount of coaxing would free it. I took it apart, some of the discs were really stuck together. Here's the thing, looking at the parts book I see 6 friction and 6 steel discs. Mine had 5 of each. They filled the basket, meaning you couldn't add another of each and still have them engage. I've researched the oil/clutch relationship, I'll go with a 20W50 now but why am I only seeing a 5 disc pack in there?

Thanks in advance.
 

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Your most important issue is the oil pressure...…..you need to strap on a gauge and check it. How you describe it, it sounds very serious, why would your oil pressure light come on at higher revs? Usually it goes out at higher revs [in a standard bike it should go out after you kick it or start it]?

The clutch sounds suss as well, for a standard clutch 6 is the magic number. Some photo's of the setup would be helpful.
 

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I agree - the oil light thing is suspect - pressure guage is the way to go

but could be a faulty oil pressure switch or the wire to the switch "earthing" out to the frame from damaged outer cover ?

just to be clear - the oil light should come on with the ignition and go out either during kickstarting or immediatly the engine starts - it should then be off while the engine runs at all speeds

never seen a 5 plate clutch -- if nothing visually obvious - measure the thickness of the plates . mainly the friction ones - maybe some aftermarket plates were fitted by a PO that were too thick so a pair of plates were left out
 

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Hi Rick,

Recently had the breather tube come off at the "T" just below the battery, sprayed lots of oil and generally made a mess. I noticed it by the low oil pressure light coming on at higher and higher RPMs.
These two things are not connected.

The large tube between the primary chaincase and the "T" is the crankcase breather, the small tube is the frame spine/tank vent; the D-section tube around the fender simply takes the vented air/oil vapour to the back of the bike. The reason for "sprayed lots of oil" is, being a 360-degree parallel twin, the crankcase volume changes as the pistons rise and fall, so there's a lot of oil vapour-laden air moving in and out of the crankcase. This will be exacerbated by worn bores as combustion pressure blows by the rings. :(

Otoh, ...

I noticed it by the low oil pressure light coming on at higher and higher RPMs. I filled it back up with what was in the garage, 10W30 dino.
I've researched the oil/clutch relationship, I'll go with a 20W50 now
:Huh ... so what did you "go with" before ...? There isn't any manual anywhere that says 10W30 oil is in any way, shape or form suitable for your Triumph's engine. If there's an internet post that says it, you found the only one in amongst innumerable posts and threads that all say 20W50, the later ones also saying 4T or "V-Twin" oil, with "JASO MA2" on the container to stop it sticking the clutch plates together ...

And the low pressure oil light first coming on at low rpm, why would you continue revving the engine to higher and higher rpm to find out the light was still on?

looking at the parts book I see 6 friction and 6 steel discs. Mine had 5 of each.
With respect, this is the least of your and the engine's potential problems. While the gauge method suggested by "tridentt150v" is one check, I would first drain the oil from the crankcase into a container you can see the bottom of - glass jar, plastic food box, etc. - and look in the bottom of the container; if there's a grey paste, the big-end plain bearings are donald already, a gauge won't tell you anything different.

If by chance you've managed to avoid buggering things with the wrong oil, then fit a pressure gauge - I suggest in place of the oil pressure switch in the timing cover. The switch/cover thread is 1/8"NPS but a NPT male end to the hose to the gauge might be easier to find.

Don't fit a gauge directly to the cover - you can't see it when you're riding and, if you hit the gauge with the front wheel, you'll need a new timing cover. :Darn

Don't use a wrench to fit the gauge hose to the timing cover, even a NPT thread should screw into the timing cover with thumb-'n'-forefinger only. When the hose fitting needs a final nip-up to seal in the timing cover, don't overtighten it, the timing cover around the pressure switch hole is very thin ...

Cold oil pressure tells you ten per cent of bugger-all - you'll need to ride the bike with the gauge fitted long enough for the oil to warm to correct operating temperature. At correct operating temperature, the closer the pressure is to the pressure quoted in the Triumph workshop manual, the better (aiui, "Normal running" pressure is 3,500 rpm and above). Some people consider 10psi per 1000 rpm to be acceptable pressure, but that would mean Triumph considered "Normal running" to be in excess of 6,500 rpm ...

Hth.

Regards,
 

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I might guess the timing cover oil seal has inverted itself. The bores must be very worn or a ring has broken. Plus all of the above answers.
 

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Discussion Starter #6
Clutch Question cont'd

Thanks for all the responses, let me answer a few of the questions and give some more details.

The oil pressure light would come on with the ignition being switched on and then go out once the engine was running. Once it warmed up the light would come on at idle. During the ride where I lost a lot of oil I noticed the light on at better than 2K rpms so I stopped. As to the choice of oil, I hadn't seen any post or information pointing me to 10/30 nor did I understand the need to use 20/50. Lesson learned, hopefully it won't get lots more expensive.

StuartMac, you are saying that the breather tube coming loose and the light coming on are not connected, correct? My assumption was that I lost so much oil I was to the point of pump starvation and was seeing the light then.

Also, are you saying that losing that much oil, and I mean quarts, would be expected from that loose breather tube? To be clear it was the small tube that vents from the frame head that came lose at the "T" junction where the "D" tube starts heading back out to the rear fender. Lots of oil sprayed all over. I topped it up with the dreaded 10/30 and it ran the same as before, quiet, smooth idle, oil light on at idle. I know what rod knock sounds like, I didn't hear it, that doesn't mean it isn't developing though.

I will get an oil pressure guage and see what's going on.

Thanks again for the responses. I'll upload some clutch pictures as well.
 

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Discussion Starter #7
OK, 6 plate clutch, suffice to say I hadn't removed the last plates. Have a laugh at my expense, I'm learning.

I'll attempt to attach a clutch picture. I'm interested in hearing whether the notches from the plates can be addressed by filing or should I be replacing things.

In the second picture if you look closely you'll see that the primary chain oiler tube is cut with a nice section missing, obviously not delivering oil where it was intended. I'll be digging around here to see if I can get some idea of how to replace that. Any suggestions would be appreciated.

I'm really not deliberately trying to butcher this thing. Appreciate your inputs.
 

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I have seen clutch baskets way worse. Dress it if you can but it looks ok
Ditto the plates

The oiler is a waste of time anyway- they get cut a lot
 

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Hi Rick,

you are saying that the breather tube coming loose and the light coming on are not connected, correct? My assumption was that I lost so much oil I was to the point of pump starvation and was seeing the light then.
are you saying that losing that much oil, and I mean quarts, would be expected from that loose breather tube?
No, specifically not, unless something is very, very wrong.

To be clear it was the small tube that vents from the frame head that came lose at the "T" junction where the "D" tube starts heading back out to the rear fender.
Yes, but the pressure (unless something connected incorrectly is pressurising the frame spine) is from the crankcase - specifically the volume reducing as the pistons descend. Ordinarily, the crankcase pressure would simply escape to atmosphere through the D-section tube.

To be clear:-

. with the frame vent pipe reconnected to the "T", if a lot of liquid oil is venting on to the road from the D-section tube, something is very, very wrong;

. if oil is not venting on to the road from the D-section tube, the bike could not possibly have lost "that much oil, and I mean quarts" from the breather tube; there isn't anything magic about either breather, they're just tubes that conduct oil vapour to behind the bike; so, if the tubes aren't connected together at the "T", oil vapour will exit from any unconnected part of the "T" and make a mess of the surrounding area of the bike;

. neither breather tube should have lots liquid oil in it, only condensed oil vapour, and because the D-section tube follows the edge of the rear fender, any oil vapour that condenses in the forward part of the tube should simply run back into the primary chaincase and then the crankcase, to be scavenged as normal back into the frame spine;

. if "that much oil, and I mean quarts" was missing from the frame spine when you checked, either you didn't put it in there or it's somewhere else on the bike - probably inside the crankcases, in which case there is a scavenge pump or pipe problem.

rod knock
didn't hear it,
You won't necessarily. But, if some of the big-end shell material has been scraped off, it'll be the reason for the grey paste in the oil drained specifically from the crankcases and the oil light being on "at higher and higher RPMs" - pressure to operate the switch comes from the restriction of the big-end clearances; if they're enlarged, the restriction is less, 'til the pump cannot maintain enough pressure to operate the switch. :(

will get an oil pressure guage and see what's going on.
Drain the crankcase first. No sense running the engine, and the oil pump, to bugger the latter sucking up big-end bearing bits, which you'll also have to clean out of the frame spine and the pipes ... :Darn

Hth.

Regards,
 

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Hi Rick, The smaller tube that came off that is vent for oil frame hooks to bottom of backbone a little ways behind steering neck. Even though the tube is located way far up it will take oil from frame & run down to breather "T" & back into motor during braking. So don't jump to conclusion it's all blow by oil. I've never seen one of these bikes blow oil out over the rear fender even with much blow by. The small tube didn't come with clamp from factory. I use clamp.

How much oil did you have to add after oil light came on? If oil was way down in frame I don't how much would run up to frame vent in that case.... Near full lots runs up. Things don't seem to be adding up.

Regarding oil feed tube to sprocket some owners do not use them. I do. Triumph eliminated it in later years so maybe it doesn't matter. It's easy to replace. The upper end of tube pushes onto metal tube in the tin breather shield. The alternator wire tube unscrews & a screw in the rear to access plate, but you may be able to replace it fine by just pushing it up. A smear of super glue on metal tube can help hold the new tube in place. The lower end is between the inner & next row of teeth. The outer teeth are on their own.

Regarding the plates sticking, the oil type is huge in effecting clutch operation. It generally takes 20-50 miles for a different type oil to work into plates & cause slip or sticking. Changing oil will often cure it in 20-50 miles. Oil type is a personal thing subject to much debate... I've found with many machines of this type it's hard to beat Mobil1 v-twin 20-50. The clutch frees well & no slip. Very good for reducing wear all around. About $10 a quart on sale. I have really become to believe in it.

Regarding basket wear it's not too bad & doesn't look like that was causing sticking. If you have a new or very sharp file I'd smooth the grooves. A few hours with a steady hand on the file should do you well. Will give you better operation & fresh start. If grooves are really worn & filed the grooves are widened a lot. In this case the clutch doesn't really release & take up perfectly in my experience. My bike is like that as we speak. I knew they were too wide, but wanted to see what it really did for myself. But from your photos I'd file it if it were me. The tops of the slots on basket can groove also from the tangs on friction plates. If they get bad can cause the plates to hang up as well. Yours doesn't look too bad.

I'd recommend removing & separating basket & drum to file. Metal chips will get into bearings if not.

A 7 plate clutch kit from Norman Hyde using 650 springs would give you a very good working clutch. Much less lever effort due to the 650 springs. I've done several to very good results. It really frees well & no slip. No need to replace pressure plate & all adjustments remain as factory specs. If clutch cable is needed you cannot beat Barnett. Swaged steel ends are very strong.

One are of concern is the thrust washer between center hub & basket. These tend to wear putting chain out of alignment & can cause drag with lever pulled also. But I doubt made plates stick. At the same time the clutch rubbers tend to only last 5 years or so it seems. When they get deteriorated the motor can feel jerky at lower speeds & on slow cornering on mountain roads. When really worn you can hear an odd clank that will startle you as you roll throttle on/off on curvy, hilly roads.

You'll need a puller for motor sprocket & clutch hub to remove basket assembly. Then separate basket from hub. After the basket & hub are separated you can see thrust washer & the 20 rollers will fall out. Don't lose any. Use grease to hold washer & bearings during assembly. On 750s the parts tend to be a press fit so pullers are needed. The inner hub is often a very tight in drum also. It won't slip apart like older 650s will. That's been my experience.

After basket, hub are separated the rubbers are accessed by removing 3 hex bolts from back side of drum. But... you must grind swage off the ends of bolts before remove. Cutoff wheel on Dremel is perfect for this. New bolts needed for assembly. I peen them.

A telltale sign of bad rubbers is black sludge around rim if drum. I might see some in photo?? Looks like the basket could be original as it has oil holes around perimeter in slots for outer plate tangs. Repros often don't have the drillings. Original drums had the 3 hex bolts swaged such it looks much like straight slot screw head. It is not! Removing with out grinding will ruin threads in cover.

I posted photos on how to do all this but can't seem to find thread. PM me your email & I'll send them to you.

I got the oil pressure test kit from Harbor Freight. Comes with all the adaptors including one that fits our bikes. Cold the pressure will be about 20-30# idling & 70+ at 4000 rpm. Depends on ambient temp & the oil you are using & idle rpm

If good go for a ride & warm motor. On a 100f day after 50 miles of continues miles expect 15-18# idle about 1000. 4000 rpm about 60-70#. Now at 65f after 10 miles idle tends to be 20-25#. This is using Mobil1 V-twin 20-50. Straight 40w hot gives lower pressures...

If you are down to 7-10# or lower cold that is bad. 7-10 or lower hot that's bad. I expect oil light will wink on. The oil switches are prone to failure but checking with a gauge is a must. If idle is really low like ready to die hot pressure will go down to 5-10#. That's normal. So keep idle at 1000 or so for idle test.

Many things can cause low pressure. Don't jump to conclusions. A systematic diagnosis will show cause. Remember the feed & return pumps are 2 separate systems in a common casting. Each part has to be looked at separately. Return to tank doesn't mean rod bearings are being properly lubricated. So indeed checking pressure with a gauge is needed.

You have a lot on your plate with clutch & oil systems. Take your time, do it right. You will be rewarded with a very well working motorcycle.

How many miles would you say is on this machine?

'76 is an excellent machine. Has a little stronger trans for this year, familiar to many left foot shift & disc brakes both ends. Still has full front fender bracing which I feel looks good & a maybe little thicker seat. Overall a very nice machine that runs & rides very well.
Don
 

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Discussion Starter #11
Thanks again all, appreciate your experience and advice.

"lots of oil" now equals precisely 1.2 quarts. I verified from the 5 quart bottle that I used which was new. Oil was running down the chain guard and generally splashed all around. When I discovered the oil mess I went looking for the culprit, found the thin frame breather tube disconnected from the T fitting and assumed that was the source. It made sense from looking at the mess as the point where the oil was coming from. I have since put a clamp on it but I'm understanding here that if it is the source something else has gone wrong.

I drained the oil, let it sit overnight, below is a picture of what I found at the bottom of the drain pan, no grey past, some fine bits of metal. Nothing bigger than what I see in the picture.

The odometer had 11K and change on it when I bought it, I put on roughly 400 miles before this oil spray issue came up. Once I reattached and clamped the breather tube to the T and filled it back up with 1.2 quarts of the 10/30 I put on roughly 40 miles after which I had the stuck clutch issue. I did not lose any oil after adding the 1.2 quarts on the 40 mile ride.

Moving forward, I'm leaning towards addressing the clutch, then reassemble, add the 20/50 and get an oil pressure guage. Does that sound reasonable or does the picture below change things?
 

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Discussion Starter #12
One thing to add, yes, I do see "black paste", it seems like the clutch rubbers are probably toast so that will be part of addressing the clutch. I'm in no rush and want to do it once and right.
 

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Hi Rick, Are the metal chips magnetic? Or alloy.

What was drained? Just frame or is this from motor sump?

How does frame screen look? Did these pass through screen or were they around outside of screen?

Have you removed the engine sump drain with it's screen? Is that metal if any magnetic?

Alloy is often ground from the primary case as chain is very close & rubs easily with 3 row chain. Look at lower rear of clutch area. Also the chain if too loose can rub on tube for alternator wires.

Black powdered metal that looks like a black sludge but is magnetic is often from rings, bores, slots of clutch basket, primary chain & teeth & many other parts. Often normal wear. Some black is not magnetic. I think that's mostly carbon from blow by & hardened oil.

However.... magnetic flakes & chips may be serious. This may be from deteriorated roller or ball bearings. Can be hard to diagnose without tear down. Can also be bits of big end rod bearings. Often rod bearing damage is accompanied by low oil pressure.... There again pressure check is needed.

Don't jump to conclusions. I think your plan of getting running & then pressure test oil press is what I'd do at this point. If oil pressure is ok, ride it more & evaluate things. 1.2 quart low is not low enough to cause damage in and of itself. I've never seen 1.2qt. low make oil light come on. Looks like you still had about 1 qt in frame. All together frame, motor sump, primary is about 2-2/3 qt.

If you want to evaluate the clutch more I think that's fine. I'd probably do that. Not hard to take apart. Sure, wash plates in gas well. Dry with clean rag & let dry overnight. Even if not recommended gas does work quite well to clean parts. Obviously a big fire hazard.

I never install plates dry. I would soak them with oil you'll use in motor at least a few hours or overnight. Make no mistake they will get oily anyway.

Measure overall thickness of plate stack. Known as stack height. New is 1.400 aprox. If thinner write down how much.

Install plates & adjust spring nuts to where dome of nut is flush with stud. Then go deeper by amount of wear on plate stack. Or... if stack is thicker, back off by the amount. Then adjust wobble by going in with one & out with other nut to maintain average tension.

Again I would use Mobil1 v-twin as I've had such good luck with clutch operation with it over several machines. This will give you a base line. Then after riding some more hundreds of miles decide what you need to get back into. At least use oil specifically stating for use with wet clutch motorcycles. That is usually a safe bet. Some car oils will work, but don't chance it now.

After evaluation if all goes well & metal chips don't keep coming, might be time to consider a real oil filter? The spin on one or in frame type clean the same. Use the one you like best. Spin on is probably easiest to install & deal with.

With your mileage the basket has appropriate wear. I expect the plates not too worn. The rubbers deteriorate over time. So I expect not too much problems with motor. Most curious as to what oil pressure is.
Don
 

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I never install plates dry. I would soak them with oil you'll use in motor at least a few hours or overnight. Make no mistake they will get oily anyway.
I agree with everything you said Don...……..
except the above, I just lightly smear with oil prior to assembly, a finger dipped in oils worth on each bonded plate, nothing on the plain plates, no soaking. The centrifugal force of the clutch essentially means that the clutch runs dry [well dryish] when the motor is going....I take this as a hint that you shouldn't over oil on assembly.

But each to their own...you do what works!!!
 

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Just get rid of the clutch and put this in: https://normanhyde.co.uk/hyde-clutch-plate-set-7-plus-1.html. It really made a noticeable difference in my bike. While your at it replace the oil pump. It's a strange system with a scavenger plunger, etc. They do offer improved versions of oil pumps too.
While the 7 plate clutch can be a good thing...….I fail to see why the oil pump needs replacing, btw it has both a feed and scavenge plunger, nothing unusual about it except for these modern times were most oil pumps are gear operated. Maybe a 650 would benefit but 750's had the 4 way valve setup. I know Morgo claim an extra 20% for theirs, but 20% better than what??? A very early 650 pump??? or a later 750 pump???

And the Morgo rotary pump...although a good unit for heavy use or racing, it is definitely not for the casual rider.
 

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I bought mine cos I was doing medium high speed sustained runs/touring where I would sit on 70 to 80 mph for 8 to 12 hours only [quickly] stopping for fuel.

But for a casual user [where priming could be an issue with the rotary] the plunger pump is much better IMO.
 

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6 plate clutch has no problem i have ever seen. Just start up,pull in lever, operate gear lever and ride off. Never sticks and a nice slick change. Mine had a new 4 valve pump 20 years ago and that requires no maintenance. If fitting a 4 valve pump, a small amount has to be removed from the timing cover or fit a T140 cover.
I did look into the Morgo rotary and it requires modification of the pressure relief valve plus the priming issue if draining the oil down. Stuck with the pump that has never required any maintenance,the 4 valve type.
It is better to get this bike running before just throwing out good parts to fit pattern ones for no reason. Clean up the clutch plates, change the rubbers and run it.
Those metal chips, as already mentioned, look like surface of the balls or rollers in the main bearings. Usually, broken surface makes a terrible noise if run so might be alright if quietish.

Check oil pressure, maintain the clutch and then see what else is a problem.















You might get an i
 
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