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wet sumped? i'm stumped. #731913
04/15/18 12:54 am
04/15/18 12:54 am
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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t ingermanson  Offline OP
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aptos, ca, usa
for those on the east coast, sorry to rub in our great weather, but...

...so, on a ride yesterday, my pre unit started blowing copious oil from the crankcase breather and it's got me stumped. i've searched the site (and the web, and my manuals) and nothing quite has the set of symptoms i'm experiencing.

the motor is a bitsa pre unit built to t120 spec. fresh crank-up rebuilt motor (300-ish miles since rebuild), rings seem to be bedded, no obvious smoking. all signs good.

i had previously added a MAP crankcase reed valve (not ball-type) breather onto the dynamo blanking plate to good affect. at the time of the rebuild, i omitted the inlet cam breathing disc and capped the tube.

before the rebuild i had plumbed the breather into a frame tube as a catchment. at the rebuild, i attached the breather to a smaller bottle so i could be more aware of what was going on in the motor. the tube is routed up from the motor, with the valve under the tank, then back to the bottle, sitting atop the gearbox. about 4 feet in length.

good oil feed pressure both at start-up and while riding- about 65-70psi. gauge fitted after the rebuild for safety. pressure release button standing proud while running. only a drip of oil after rides.

norton style screw-on oil filter added to the return, before the rocker box split.

yesterday's ride finished with me getting back to shop with the bottle having overflowed and coated everything below and behind the bottle in oil. dropped the sump plug, getting about 1/2 cup (US)/150ml of oil from the sump.

aftermarket oil tank, but up until now, almost no issues. last week i tried to mitigate the oil tank cap's leak by making the vent hole a bit smaller, so i undid that to see if the smaller hole had pressurized the oil tank and was forcing all the return into the rocker boxes.

double bagged the breather bottle with thick plastic bags. went on a short ride of about 25 miles to see what happens now. varied speeds and revs.

halfway through the ride, noticed oil (not the milky stuff- clean oil) in the breather's bags and headed home. right after getting back to the shop, i dropped the sump plug, same amount of oil in sump. nuts.

pulled off the timing cover. inspected the oil pump. the feed plunger is a bit worn and doesn't hold a great vacuum with the thumb-on-the-holes check, and is a little scored. return (larger) plunger has good vacuum and is very lightly visibly worn, but not scored. both springs, balls, and seats look fine- no obvious debris. pump gasket was still good, nuts tight. reseated the balls at motor rebuild.

checked the oil filter. it was VERY DIFFICULT to unscrew, and very full, as if pressurized. nothing to note in the oil. changed the filter with the break-in oil at 100 miles. now using torco 20w-50.

blew compressed air through the breather, feed, return-to-filter, and filter-to-tank/boxes lines and seemingly no obstructions.

i'm at a loss here. up until yesterday, everything was going fine, with a teaspoon-ish of the milky oil in the bottle per 50-ish miles. no biggie. all of a sudden i'm going through rags and degreaser like nobody's business! could the emgo filter have plugged? could the oil pump have given up the ghost that suddenly? combo of the two? suddenly, at the same time? weird...

anybody got ideas?

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Re: wet sumped? i'm stumped. [Re: t ingermanson] #731916
04/15/18 1:25 am
04/15/18 1:25 am
Joined: Jul 2015
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Los Angeles
dandruff Offline
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My suggestion would be to bypass the oil filter and see if the sump is less full. That tiny plunger pump was not designed to push oil through a filter. There are a lot of things that can influence how much oil ends up in the sump, a restrictive filter can be one of them. In theory it is good practice to filter your oil, but only if the pump is up to the job, and the rest of the system is engineered for it. Good luck!

Re: wet sumped? i'm stumped. [Re: dandruff] #731921
04/15/18 1:48 am
04/15/18 1:48 am
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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thanks, dan.

that sounds like a good check. i forgot to mention the oil coming out at the froth tower seemed like an ok amount, but in spurts with gaps between spurts.

does 1/2c seem like too much oil in the sump?

andy granelli says hi.

Re: wet sumped? i'm stumped. [Re: NickL] #731922
04/15/18 1:56 am
04/15/18 1:56 am
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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yes. air blows through with no problem with the sump plate on or off.

Re: wet sumped? i'm stumped. [Re: NickL] #731925
04/15/18 3:11 am
04/15/18 3:11 am
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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yes. plumbed the right way, according to the arrows cast into the body.

after inspection of the pump, i cleaned the pump and reseated the balls. will have to wait to get some gaskets to reassemble the motor before i can try again though.

i've never used one of these filters previous to this, so it's probably worth re-routing the return, just to make sure. it's a good thing to check off the list, if nothing else.

still open to all ideas though.

seeing as the return plunger still seemed to be good, is there a pump with a slight increase in volume? those rotary pumps seem a bit much for road riding and may end with only a slightly different oily outcome...

Re: wet sumped? i'm stumped. [Re: t ingermanson] #731929
04/15/18 4:39 am
04/15/18 4:39 am
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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aptos, ca, usa
i figured the stock style pump would be adequate for anything i'm doing on the roads. the rotaries seem very much overkill for my use.

the scavenge tube seems to be at the correct height and is not loose. when i rebuilt the motor, the tube's mounting screw was tight enough that i stopped bothering with it for fear of a bigger problem rearing it's head. still tight as i try to wiggle the tube now.

the big mystery to me is that a bit less than 150cc of oil doesn't seem to be enough to be wet sumping. certainly not blowing out the breather in such prodigious amounts. or is it?

Re: wet sumped? i'm stumped. [Re: t ingermanson] #731932
04/15/18 6:37 am
04/15/18 6:37 am
Joined: Jan 2017
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Pleasant Hill, California USA
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TR7RVMan Offline
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Hi t ingermanson, I agree about our weather.... Yesterday did Mt. Hamilton, today Oakland hills. Was 82f today. Normally unusually to see Brit bikes on road, but today saw 2 unit Bonnies & a bunch of vintage Hondas. John & I are pretty much the only ones to ride regularly. At least twice a week. Our normal coffee run is 50-100 miles. The bikes work great.

Back to your bike. I'm not clear on when you installed the reed valve. Was it before the motor overhaul of after?

If before, you were running both disc breather & reed valve?

After the overhaul it was fine then started acting up?

I have no experience installing reed on Triumphs so take my thoughts as just thoughts!

Very odd this would spontaneously start happening. I do have some experience with oil pumps & "Norton type" spin on filters.

I can assure you the pump can effortlessly pump oil through the filter. A good return pump will suck at least 21" vacuum almost instantly & easily put out 100 psi pressure.

I've tested these pumps several times & have observed that. On the pumps that failed the "vacuum" test on bench by pulling out plungers a ways all the good pumps held the oil level perfectly for several seconds. Not a trace of falling oil in bore.

The ones where oil fell the balls were leaking & it did not make good pressure and oil light came on. These were all unit motors. I have never been able to get a leaking ball to stop leaking by "seating" ball with punch as instructed in shop manual. Visually the seat looked worn out of round. A like to take pump apart over white paper towel as much as possible to try to see any dirt etc. that may be holding ball open. Usually you can find the dirt, or more often a rubber chip from hose or piece of gasket. After cleaning retesting shows no drop in oil while withdrawing plunger. I've often seen minor scratching on plungers, but they worked fine. Obviously a very loose plunger or bad scratches would cause a problem.

Since your dropping oil was in feed side that would give low oil pressure or volume to crank, but not effect the scavenge side. Remember feed & scavenge are stand alone systems that only share a common pump casting.

Regarding oil in motor sump I couldn't find printed spec in shop manual. May have overlooked it. I've checked several later unit motor sumps & they reliably drain 100-120cc depending on where oil scavenge cycle was just finished pumping back oil or just ready to. The early unit motors have a longer scavenge tube so may drain out a little less. I've not checked those.

But I can say if the return pump is not pumping enough back to tank the level in tank will drop rather quickly & over some miles the oil gets so much in motor it will smoke like mad. When you drain sump a huge amount of oil comes out. So I doubt if your return system is the problem in a direct way. The filter has a 7-18# by pass depending on the filter brand/type. I expect the by pass never opens as the oil volume is so low.

Again I don't know how much oil to expect to drain from pre unit. The bottom of motor is different from unit motor so it may hold a little more. To me 150cc is not horrible.

If return pump doesn't work tank will be very low & all that oil is in crank case. Like a quart or more & motor will start to run odd & smoke really bad.

These pumps are positive displacement, meaning 1 stroke of piston pumps a fixed amount of oil. No matter the oil pressure on gauge the oil volume is similar. The return pump plunger is a little larger so it always returns a little more oil than feed plunger put in. The rest is a tiny bit of air or nothing until oil in bottom of motor is deep enough for return plunger to return it. That's why you see spurts at lower RPM. At high RPM the spurts are still happening, but so close together it looks like a solid stream. The oil balance is pretty close & works well.

As far as the oil filter in return line is concerned the pump just sees it as a very fat piece of hose. It fills with oil then the oil passes through the same as it does the hose. Generally it will be full visually when you remove it.

If you are getting too much oil into rocker hose compared to tank return, the oil level will drop in tank & the sump will fill with oil resulting in odd running & much smoking. Personally I've never seen that.

I've some experience with the disc breathers on inlet cam. However I have no experience with the add on breather that you speak of.

But in either case the idea is to let the air & blow by out of case, & not back in. So the inside of motor is under a slight negative pressure or vacuum.

The rotating inlet cam has about a 1/4" in the side of it for the air/fumes to enter to disc, but the rotation acts as an oil separator to reduce liquid oil from entering disc.

So maybe?? the MAP reed valve was not doing much so it didn't suck much oil. That is a guess!

I don't know how much oil is in the cam gear case at the old generator area. On unit motors the pressure relief valve return sprays oil onto exhaust cam gear. I realize the non unit motor oil relief valve is near end of crank.

I couldn't say if changing hole in oil filler cap would cause this. However the tank must be well vented. Since you went back to original hole, no help that was not a factor. I doubt if that could have done any damage.

Here's a thought.... What if you put reed valve on original disc valve tube. Again running tube high on frame. That will allow inlet cam to be an oil separator, yet reed valve handle vapor control.

The disc breather system has a propensity to spit oil, sometimes a 2" circle. Sometimes more. Doing experiments on '69 Bonnie routing fender vent tube high as possible, & the vent tube on tank low as possible, was able to reduce oil spitting as most the oil drained back into tank. Used catch can at times rather as you did.

The '69 has covered about 700 miles now since rebuild. Used Torco TBO 40w for 400 miles. Then went to Mobil1 v-twin 20-50 after that. Has Norton type spin on filter as you did. The oil pressure went up slightly with Mobil1 with fully heat soaked motor. As you, no smoke or oil consumption at all during break in or now.

Breather disc is all stock. Y pipe to motor/tank/fender is they type on seat post tube. As I said ran the tank vent low as possible & hose over fender high as possible. Fender hose is maybe 1/4-1/2" higher. Vent connection height on tank is fixed so that's the best we can do. Now just gets a little oil drip now & then, mostly oily condensate dripping. The rubber hose from breather on motor to Y connector is mostly full of oil at all times. Seems the fumes just bubble through oil. Following bike on cold morning start up I can see "steam" like condensate vapor coming from breather tube. So it seems the oil that gets into rubber tube is working its way back to tank. Would be fun to use clear hose for a test to see what's actually happening.

I understand some (all??) pre unit motors don't connect motor breather hose with oil tank vent hose. My experience on pre unit bikes is rather limited.

I don't think anything is wrong with motor or oil pump. My hunch is the breather reed is acting up or removing disc has made reed work & there is no oil separator??

Where is reed located? What if you located reed high as possible above motor so hose might act as separator so to speak?? If possible put catch can such it could drain back into motor. You know at times the breather hose on the '69 Bonnie & even my '73 Tiger sucks in air which means it may suck oil back in with it.

So do some experiments & see what you come up with. Let us know.
Don


1973 Tiger 750
Re: wet sumped? i'm stumped. [Re: t ingermanson] #731939
04/15/18 8:34 am
04/15/18 8:34 am
Joined: Aug 2001
Posts: 7,459
scotland
triton thrasher Online content
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What diameter is the breather hose? Is it vertical from the dynamo position to the petrol tank base? A 3/4" diameter vertical section with as much vertical length as you can arrange should make it hard for oil to find its way out. A big pipe like that makes a good breather with or without a valve.

I expect the breather valve fitting instructions say to put the valve close to the crankcase. Good advice.

Is there any sort of oil catching gauze in the breather line?

If you have any doubts about the oil filter, just bypass it. Take its inlet and outlet hoses off and connect them together with a couple of inches of metal pipe.

Is there clearance (1/4" should be safe) between the end of the scavenge pipe and the sump plate? Can be an issue with aftermarket or home-made replacement plates.


Amateur Loctite enthusiast.
Re: wet sumped? i'm stumped. [Re: TR7RVMan] #731962
04/15/18 4:40 pm
04/15/18 4:40 pm
Joined: Mar 2017
Posts: 31
aptos, ca, usa
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t ingermanson Offline OP
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don,
yes. it's really the best time of year for motoring about. everything is green and not so many tourists on the roads. temperatures are perfect and all is good. we're lucky! hopefully the rain will continue and we won't dry up and blow away or burn away. nothing is free. even good weather!

the reed valve was added previous to the rebuild, but there were other issues (hence the rebuild) causing me to rule out it's perfect function. the cam breather never gave me any grief (or oil) to speak of, so i felt comfortable in blocking it off, relying on the reed only. MAP confirmed by feelings of this.

the oil tank does have another vent tube other than the monza cap. i've blown air through it. it's ok. only an absolute minimum of oil in it's catchment bottle, before or after the cap vent restriction. i've never plumbed the breather into the tank on the bike, especially when the output was formerly so low. no reason to spoil the oil with the nasty crap that comes out of the breather.

i'm generally familiar with the quantity of oil in the sump, quantity of oil being pumped through the feed and return, as well as the function of the pump. to me, all seems ok, but things just aren't adding up toward the outcome of blowing oil. it seems there's a variable somewhere that is the culprit beyond i've been able to ascertain.

tt,
the breather tube is a 3/4" i.d. to join with the MAP valve's inlet. it leaves the case forward diagonally for a couple inches, then vertical, to the headstock, where the hardware resides, about 14" from the case. the breather's exit is at 90 degrees, toward the back, with a 3/8" id hose, back to the bottle. when i attached the breather to the motor, i ran the routing past the gentleman at MAP (mario, marino?) and he said that sounded fine. there is no screening of any sort in the tube. seems screening, once wet with oil, might cause more trouble than it solves (?).

there seems to be enough room between the bottom of the scavenge tube and the sump plate. most certainly 1/4".

dan, nick, don, tt,
thanks all for your thoughts and help. this is really helping by, if nothing else, talking through it! there's gotta be something here somewhere.

the oddest thing to me is it happened so (seemingly) suddenly. no issues like this before the rebuild, or the previous 250-ish miles after the rebuild. obviously the feed and return ratio is off if the correct-ish amount is in the sump, tank, and the amount coating my back wheel is far more than preferable.

with no obvious causation, my current thoughts are to bypass the filter (if only to remove that as a concern), and put it back together with new oil and see what happens after all the lines have had air blown through them. if all is well, add the filter back into the mix with a new screw-on unit. it could have been an errant bit of gasket or jointing compound that made it through the maze despite my being very careful with the reassembly to avoid all that. sometimes cleaning and reassembly does the trick. i also have an xs-type reed valve to add the the cam breather, should i need to, but i'm loathe to do all that work unless all else fails.

while not necessarily relevant to the issue at hand, i'm also a bit nervous about the feed plunger of the pump being so worn as to not pass the thumb-vacuum test. while it functions now, putting a known worn item into the motor is asking for trouble in the future. maybe i'll replace the pump a bit later to narrow the focus of this issue and it's symptoms.

Re: wet sumped? i'm stumped. [Re: t ingermanson] #731975
04/15/18 6:25 pm
04/15/18 6:25 pm
Joined: Sep 2008
Posts: 813
Skudeneshavn Norway
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Stein Roger Online content

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Hi, Ingermanson (Swedish name?)

You're giving a good account of what you have done and how. I'd forget about the filter, the plunger pump is capable of producing hundreds of psi, even if a little worn.
Even a plugged filter wouldn't stop the oil return, the filter mesh would sooner burst.
I believe your timing gears pumps oil up into your vertical breather pipe, effectively plugging it. The oil is then pumped up and out by the crankcase pressure.
I don't think the dynamo drive is a good place for a breather.

Re: wet sumped? i'm stumped. [Re: t ingermanson] #731988
04/15/18 8:17 pm
04/15/18 8:17 pm
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Isle of Wight, UK
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koan58 Offline
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The cam disc breather works fine for most situations, why did you feel the need to change it?
If you had to, why not put the reed valve there? I suspect that you have created a problem that wasn't there in the first place.
There is a lot of oil in the timing case, and should be, it feeds the timing side main bearing as well as the gears and bushes on that side.
I know that location has been used many times before, I'm not sure that it is useful though.
From that location, as TT mentioned, it should be a large vertical diameter tube before the valve (actually I'm not sure of the value of the valve), to give plenty of opportunity for oil vapour to coalesce and drip back down.

Re: wet sumped? i'm stumped. [Re: t ingermanson] #731994
04/15/18 9:10 pm
04/15/18 9:10 pm
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scotland
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The original timed breather is fine if you go slow enough. Go fast and it causes leaks.

The dynamo mounting position worked fine for me as a breather position and has done for many others.


Amateur Loctite enthusiast.
Re: wet sumped? i'm stumped. [Re: t ingermanson] #732003
04/15/18 10:46 pm
04/15/18 10:46 pm
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Isle of Wight, UK
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TT I do my best to go slow enough but sometimes time gets in the way. Buzzing about on the island, no leaks are evident. When I go M27 or M3 70-80mph a little sweating from the barrel joint occurs, a smudge. I think that is more a matter of me not paying enough attention to tightening things on an (at least) occasional basis, rather than a defect of the machine.
The only reason the standard breather couldn't cope, would be if there is too much blow-by through the rings. It wasn't intended to deal with that.

Re: wet sumped? i'm stumped. [Re: Stein Roger] #732016
04/16/18 1:10 am
04/16/18 1:10 am
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aptos, ca, usa
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t ingermanson Offline OP
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roger,
funny you should ask about the name. it's a truly american story of when coming to the country, the immigration office thought svensen (swedish) was far to "ethnic", so the name ingermanson was assigned. my parents are quite into genealogy, and apparently there are several families that came through the same office the same day and were given several versions of the same name, such as, ingemanson, ingemason, etc etc, yet none of us are related. i have relatives from all the scandinavian countries, my grandmother being from helsinki with the family name luato.

koan58,
there was a fair amount of leaking from the case, and i was trying to minimize oiling into the primary. i tried the reed to help alleviate those leaks and seemed to work when the cam breather seemed to do nothing to those ends. i can use the xs-style reed valve on the cam breather, but the orientation of the inlet and outlet tubes in conjunction with the downward trajectory of the cam breather made it quite awkward to plumb. also, the MAP one uses a larger diameter tube, with a vertical orientation. it worked fine for a while until the rebuild, and for the first 250 miles when one can expect oil, blow-by and other difficulties. maybe a leakdown test is in order to make sure rings are happy?

as far as the location of the breather in the timing chest, i've seen it done many times on race bikes, where oiling the outside of your bike is generally frowned upon. while i've no long term experience with it, there can only be a million tricks to it, so how hard can it be? **wink** the placement may not be ideal, but the motor isn't hotrodded and i'm not even tickling the underside of redline. our roads are far too twisty or congested for that.

tt,
should there be a gauze in the breather tube as you mentioned? as an experiment, i put a bit of steel wool in a hose and it was noticeably harder to blow through, especially once oily, so i omitted it. maybe that's exactly why i need it...

i think the way to proceed is to clean everything well, reassemble and start with a "clean slate" to see what happens. that will take the variable of a plugged case orifice or hose out of the mix. if it continues, then start replacing components, cheap to expensive, one at a time starting with a larger breather hose and ending with me buying a bmw.

it seems the problem of over oiling has so far been self-mitigating as long as i contain the oil coming out of the breather and the tank topped up. if i'm doing short rides to figure this out (and all else is ok on the motorbike) i'm not going to do damage, am i? i'm going on the assumption that 150cc of oil is the most that the breather is allowing in the case. i know i've got good feed pressure, and oil is making back into the tank and top end, so things shouldn't get too weird, right?

Re: wet sumped? i'm stumped. [Re: t ingermanson] #732046
04/16/18 9:38 am
04/16/18 9:38 am
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Skudeneshavn Norway
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Stein Roger Online content

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Well I bow to real experience, and kindly ask you to ignore my offering.

I hooked up an XS valve to the breather pipe on a 6T recently, with the pipe making a "U" turn up to the valve. It has a tendency to fill with oil and is not a solution I'm happy with. The original set up was buggered beyond repair. I'm trying to figure out a better way, but without drilling a new hole somewhere, it isn't easy. One idea is to enlarge the drain holes in the tappet guide blocks and let it breathe through the R/Boxes, but then the engine would have to come apart again.

Immigration; Svenson became Ingermanson, wow! My grandmother's two brothers both went to the USA, where the immigration office changed their surnames from Lie, for obvious reasons, to Lee, which is how it's pronounced in Norwegian anyway. Rudolf was changed to Rudolph, while poor Karsten became Carson. I suppose my name would have become something like Ingermanson too, a hundred years ago!
Another relative got to keep hers, Joergensen, so I guess it depended on who you met at Immigration?
Interesting stuff.
Sorry, no hi-jack intended, got carried away...

Re: wet sumped? i'm stumped. [Re: t ingermanson] #732052
04/16/18 1:21 pm
04/16/18 1:21 pm
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Mikes XS 650 site shows a 1.5 mm hole in the reed block to allow oil to drain back, will only work if the oil can run down hill.SEE her
https://www.mikesxs.net/pdf/manuals/15-0677.pdf

I have modded my reed with this hole but havnt got the bike running yet to test.

Last edited by gavin eisler; 04/16/18 1:22 pm.

71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: wet sumped? i'm stumped. [Re: gavin eisler] #732058
04/16/18 2:04 pm
04/16/18 2:04 pm
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Skudeneshavn Norway
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Stein Roger Online content

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I've used the valve on many engines, and never bothered with that hole. Can't see what difference it would make.
The valves never seem to collect any oil, and the reed doesn't really close all that tight anyway.

Re: wet sumped? i'm stumped. [Re: Stein Roger] #732064
04/16/18 3:26 pm
04/16/18 3:26 pm
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aptos, ca, usa
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t ingermanson Offline OP
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t ingermanson  Offline OP
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roger,
no hijack, just a nice interlude from the head scratching/banging. i'm sure the immigration officers meant no malice, and were just looking to try and help integrate people more fluidly. hard to imagine though that ingermanson is easier in someone's mind than svensen! i've thought about changing it once my parents have past. i'm the last of the male ingermansons.

that weird loop in the hose is why i omitted the reed valve on the cam breather and just capped it. i figured that low point was going to be annoying, and behind all those parts when i was forced to deal with it. those valves are supposed to solve problems not cause them! i'm with you trying to come up with the least invasive breathing method. the MAP one did so well for hundreds of miles, but now won't do 10, so something obviously changed.

i'm happy to entertain all thoughts and suggestions because i'm at a loss currently, and obviously in the dark. there are bound to be differing opinions, and i'm happy to listen to them all. both may even be right! the differing approaches is a good thing toward prizing out the best methods.

gavin,
i've seen that mod listed as the thing to do. however, i didn't use that valve due to it's small diameter inlet tube. if i was going to have one breather, i wanted the largest "plenum chamber" hose i could get between the case and the valve. also, i found the routing seemed awkward on the pre unit, as mentioned. did you mount one on a pre unit? if so, how so?

our splendid weather from days ago has disappeared for a day or two, so that'll keep me from wanting to hastily put things back together and get out on the road. that, and i should pretend to do my job as well, at least for a couple days.

Re: wet sumped? i'm stumped. [Re: ] #732075
04/16/18 4:52 pm
04/16/18 4:52 pm
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aptos, ca, usa
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t ingermanson Offline OP
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taff,
thanks for that. my case didn't have the seal originally, so i made and installed a seal carrier and added the seal when i put in a belt drive a while ago. the seal was removed and replaced when the main bearing was replaced at the time of the rebuild, but that's a good check to see if something happened to that seal, even if it seemed good upon reassembly. i had been fussing with the primary case and clutch a bit back when i replaced the mainshaft bush in the gearbox, so maybe something moved or came loose, even if the seal orientation is correct. i imagine if that seal had failed there would be oil in the primary case as well as through the breather. i'll add that to the list to check as well!

Re: wet sumped? i'm stumped. [Re: t ingermanson] #732084
04/16/18 5:54 pm
04/16/18 5:54 pm
Joined: Aug 2001
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scotland
triton thrasher Online content
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It is not going to suck much air in through an oil seal.


Amateur Loctite enthusiast.
Re: wet sumped? i'm stumped. [Re: t ingermanson] #732087
04/16/18 6:36 pm
04/16/18 6:36 pm
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Isle of Wight, UK
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koan58 Offline
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I'm not so sure that the driveside crank oil seal does much more than simply provide a barrier.
I suspect that most pre-units are not running such a seal anyway, and if they do, it is for similar reasons as t.ing, to prevent oil escaping the crankcase into an otherwise dry beltdrive.
I ran my pre-unit for ~20 years with no seal (Though one is shown in some parts diagrams, I never could find one that would go into and stay in the shallow recess) and it didn't seem to cause any problems.
Then I had the case modified, such that it had a collar welded on that accepted the unit oil seal (I had been using unit duplex primary drive for most of the time). There were a few other trivial things done to make it workable.
Now there's much fuss made about the direction of this oil seal. The first thing I'd say is it's nothing like the application at the crank end of the oil supply, where pressure differences between one side and the other can be >100psi.
In the case of the driveside sprocket oil seal, just how much pressure difference do you imagine? It seems to be generally assumed that there is an average negative pressure in the crankcase. I suspect that is a little hopeful.
It would be interesting to hear from someone who has actually measured this.
My intuition is that the breather system only endeavours to minimise pressure within the crankcase. I would be surprised if any significant vacuum was developed in these crankcases.
I certainly cannot envisage it being enough to trouble the oil seal, either which way.

Re: wet sumped? i'm stumped. [Re: t ingermanson] #732089
04/16/18 6:43 pm
04/16/18 6:43 pm
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argyll. scotland, uk
gavin eisler Offline
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I bought my reed valve off eBay, its originally a yamaha 125 part, it is similar to the Mikes type but the inlet / outlet are at opposite ends 180 apart, easier for an in line fitting, I have a staight stub from the timing plug on my A65 _ case front central ish, slightly RHS, then a 90 degree hose bend up to the valve block and 12mm ID hose running up and to the rear to a catch bottle under the seat, this is all entirely untested so far, but I thought with the location its bound to get some oil off the flywheel so I drilled the 1.5 mm hole, time will tell, I plugged my timed breather exit with a cork turned to fit and a bit of glue. i was told it is important to get the valve as close to the source as possible .


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: wet sumped? i'm stumped. [Re: t ingermanson] #732178
04/17/18 2:47 pm
04/17/18 2:47 pm
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Skudeneshavn Norway
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Stein Roger Online content

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Some Norton guy, possibly Jim Comstock? has measured crankcase pressures on a Norton twin. It was found that a reed valve was able to lower the pressure significantly but it varied with revs. At one point there was actually lower than ambient pressure in there.
Colorado Norton Works markets custom reed valve units developed by Comstock for various Norton twins, They actually claim "a vacuum" up to 4000 rpm... While vacuum actually means an absolute lack of pressure, what they mean is of course a depression compared to ambient. An XS valve is small but that only means it takes a wee bit longer to pump down the pressure.
I too suspect Triumph's disc valve system to be on the puny side, and breathes through a tortuous route, but if everything is up to par, the rings sealing well etc, I do think it works pretty well.
With too much blow by, neither system will work well, nor should it. A worn engine needs to be fixed, not mitigated.

But here we have a good engine with a good breather system.
I guess I'm stumped too, which doesn't help you much.

But Norton's breathes into the (well vented) oil tank, on a Combat the breather is situated directly on the crank case, and as they're prone to filling their sumps when sitting for a while, more oil is evacuated by the breather than by the return pump, until the sump is cleared..
t ingermanson suggested to route the return to the oil tank, and why not. Just make sure to vent the tank adequately.
Worth a try I think.

Last edited by Stein Roger; 04/17/18 2:51 pm.
Re: wet sumped? i'm stumped. [Re: t ingermanson] #732192
04/17/18 4:20 pm
04/17/18 4:20 pm
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aptos, ca, usa
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t ingermanson Offline OP
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...so...

good news, in a way.

did a leak down test and it appears the right cylinder's rings are not quite seated and perhaps deteriorating. before the ill-fated ride, i had rechecked the tappet clearance and did a quickie compression test. both cylinders appeared to be fine. once the oiling issues started, i didn't recheck, but should have knowing that 90% of the time, if there is a problem after a rebuild, it's the rings. the right cylinder was a little slow bedding in compared to the left, but all seemed ok after 50-ish miles (compression test, eyeballing the tops of the pistons thru the plug hole).

good news is the oil is not dark or burnt smelling, and there was no real smoke to speak of, so hopefully things were caught before it got too bad. glad i didn't button it back up and go for another spin, still concentrating on the oiling and breather. also glad i had routed the breather into the bottle to keep an eye on things!

when re-building i tried to follow all the instructions and best practices for a dry assembly, aggressive ring bed, proper head torque and re-torque, but something must have been amiss in my procedure.

i'm going to pop off the head and take a look later today. hopefully the rings are still in one piece, bores aren't scored and, it's a matter of a good clean up, a couple of new rings, and button it all back up and try again. i'll keep everyone posted as to the condition of the rings and bores.

thanks, everyone! i've heard some new things and learned some things. hopefully i'll learn a bit more and be able to apply it to this next attempt. i'm still listening if anyone wants to knock me about for being tunnel-visioned and not checking what should have been the obvious!

Re: wet sumped? i'm stumped. [Re: t ingermanson] #732266
04/18/18 5:40 am
04/18/18 5:40 am
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aptos, ca, usa
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t ingermanson Offline OP
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well, things have taken a turn for the unfortunate.

pulled the head, right cylinder has just a bit of scoring. visible but not feel-able. pulled the barrels and rings and pistons actually look ok. all the rings are right side up and where it should be. then i noticed a rather uncomfortably large chunk of magnetic metal sitting on the case kind of under where the base gasket once was. uh-oh. found one more between the barrels on the underside of the cylinders.

pulled the sump filter, a couple/few more much smaller pieces.

the bits are rough and unfinished on one side, and much cleaner and shiny on the other, shaped like bits of a cam's flange that butts against the drive side bush, but all looks ok and intact from looking into the case from above, and below with a mirror and light.

looks like the crank will be making a reappearance in the next couple days.

once again, i'll keep posting if anyone is at all interested, or we can just call the thread over and chalk it up to blow-by from "general cylinder scoring". someone please let me know.

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