Question about smoke and sight glass oil level (pics)

[boostd4]

Hi, I'm a new owner of a 1985 K100RS.  I've been searching like crazy and have an idea what the right answer is but I thought I'd query the experienced folk here.


A little history of the bike...  I was told it has about 18,000 miles on it.  One family owned (Dad owned, then Uncle, then son, then me).  The bike was down for about 2 years while the son decided to convert it to a cafe/scrambler style bike.  He got it in a rideable state with a few cosmetic things left to do.  He said he's been riding it off and on for the last year, but it will sit for months at a time.


The bike smokes on start up - I know this can be normal.  When I bought the bike, he had ridden it about 20 minutes to meet me and it did not smoke at all while idling on the sidestand, even if I revved it good.  After getting it home on a truck, my first attempt at starting it, it smoked for about 1 minute (pretty heavy at first, but then thinned out).  I rode it around the block a few times, and it appeared to stop smoking.  Having researched the issue prior, I leaned it to the right after idling for a few seconds and shut it off.  Then I let it drain for a few more seconds, then parked it on the center stand.


When I started it today, it seemed to smoke less on startup and it went away quicker.  BUT...  after riding it for a while and engine temps up, it seems to smoke on decel.  Does this necessarily mean bad valve seals?  Does anyone make a tool to change the valve seals with the head still on (in the bike)?


Lastly, I checked the site glass to see what the oil level looked like.  Never having had a K bike before I'm not sure if what i'm seeing is a site glass that's full to the very top with oil, or just stained from years of use...  I've attached a picture of the site glass, perhaps one of you kind gents can evaluate.  Short of draining the oil and adding the proper amount, I'm not sure how else I could tell - perhaps change the site glass when I do this?


Would overfilled oil cause more smoking?


Thanks a million, the forum is a great source of knowledge!

[Elipten]

For me it is hard to tell if sight glass if clouded over or not.  Oil level should be at level of do in center up to red circle.  Not below the dot as that is not ideal.

I would drain the oil a bit and see if the air bubble becomes visible in sight glass.

Overfilled situation not ideal as can cause damage to engine.


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[Martin]

You could also try tilting the bike while someone looks at the sight glass.
Regards Martin.

[koapono]

put bike on side stand and see if level in glass changes.

[rbm]

The sump is overfilled with oil.  Drain some from the sump until the level reaches the dot on the sight glass with the bike on the centre stand on level ground.  Overfilling will result in the smoking you are seeing while riding.  Even with the correct oil level, it is possible for the K75 to smoke when starting up if it was set on the sidestand after its last ride.  The cure for that is to tilt the bike to the right for 10-20 seconds after turning it off but before putting it on the sidestand.

[Christopherguzzi]

From what I can see of your picture, your site glass looks plenty clear enough to tell the oil level and it appears to be over filled beyond the top of the site glass.  You could try draining into a clean vessel and watch until you see the oil level drop.  Be mindful, however, that it can be difficult to get the drain plug threaded quickly enough to stop the oil from flowing (thus the clean vessel so you can add oil back in as needed). 


Welcome to the forum and enjoy your "new" bike.

[Filmcamera]

Very interesting post, I just learned my bike has been overfilled since I got it!

I have no little dot in the middle of the sight glass and when I got the bike it was filled to the top of the red circle so I have continued to do the same.

Now I know better and will adjust the level.

Thanks for the post

[boostd4]

I'll drain it completely today and fill it properly and see what happens.


If the smoking post start-up doesn't stop after a couple hundred hard miles I think I'm going to change the valve seals.  I work for a BMW car dealership and BMW has several special tools for specific car engines to compress the valve springs while the engine is in the car.


I was reading the owner's manual posted in this forum and it shows what looks to be a similar special tool (see the picture attached) - this was on a 3 cylinder but the manual says k75/k100, I'm hoping it's the same.  The picture makes it looks like the tool is installed on the top of the cylinder head....  meaning, it could potentially be done with the head on the block in the car (compressed air or rope to keep the valve up).  This would save a lot of labor - none of the intake/exhaust/fuel would have to come apart, no head gasket/bolts/cam timing would need doing...


Has anyone used this tool, or successfully replaced valve stem seals with the head on the block in the frame?

[BrickMW]

My site glass does the same / looks the same (over full) when on the center stand. Goes to normal once off the stand and standing straight up.

**EDIT** With the engine running, on the center stand, my oil level shows dead center of site glass, right through the dot... with the prescribed 3.75 L of oil installed (4 qts minus the 0.04 qt that sticks to the inside of the bottles)

Starting with a fresh oil change wouldn't be a bad thing. Lots of peace of mind knowing 100% you are running the right filter, right oil, right amount. Thinner oil will smoke more. I cured my startup smoke sessions with fresh Mobile 1 15w 50.


I would't fret on the valve seals too much yet. Especially if you are still blowing cobwebs out. Get fresh oil in and monitor usage while you brick as many miles as possible.

[Chaos]

When you drain the oil look at the sight glass, you should be able to see the silver back plate easily.  If not the plastic is clouded and you may want to change it.  As for smoking, mine smoked like a chimney from day one starting up at the dealer.  Not every time, maybe 1 out of 5 starts.  Leaning bike to the right after shutting off and parking on the centerstand helps, along with not overfilling the oil.  After 31 years I don't worry about it. 

Helpful hint....when starting bike in public get in position to make a quick getaway BEFORE hitting the start button.  This way you don't have to explain to bystanders the nature of sideways engines :yes

[Filmcamera]

I always use the centerstand so have no smoking issues.  I normally start it up on the centerstand, let it warm a little and off I go without my departure leaving behind a cloud of blue smoke  :riding:

[Laitch]

. . . it will sit for months at a time.

Change the oil and filter if you haven't already. Start riding it regularly after you get the oil level stable somewhere at or above the circle's center/center dot and below the top of the circle. The oil level usually should be visible when the bike is on the center stand. Follow Chaos's and rbm's advice about leaning it to the right after shut off. Like BrickMW suggests, it might settle down after a few hundred miles of riding. Don't get ahead of yourself.

You'd also better remove the fuel cap assembly, remove the fuel and check the tank for sediment from decomposing rubber and fuel degradation before you go much further because based on the little history of your bike, you're unlikely to ride much further if the bike has a gummed up fuel system.

[The Mighty Gryphon]

I agree on the diagnosis of an overfilled oil level.  An oil change is the first thing I would do to any bike that is new to me.  Don't refill to above the dot.

As to the smoking, I have a brick with a lot of miles on it that sat for several years.  I suspect it had some stuck oil control rings as smoking and oil consumption has decreased after several thousand miles of riding.  It wasn't until I was riding in lower gears that the oil consumption really started to decrease.  Running at 4500 t0 6000 rpm seems to be what loosened the rings up. 

I had thought the problem was valve stem oil seals, but replacing them only helped a little with oil consumption.  It wasn't until I started winding out the engine that oil use really decreased.

[boostd4]

Thanks for all the responses!


I think you guys are right on point after my findings today... so...  yesterday I did the tilt-right thing before parking it on the center stand.   Today I walked it out of the garage, put the garage door down (or I'd fill up the garage with oil smoke) and started her up...   MUCH LESS SMOKE on startup.  Still noticeable, but not large clouds.  At this point I'm thinking, "ok, it's just the side stand and downtime."


So I go to the parts store anyway to get oil just so I can verify the oil level.  They have Castrol GTX 20w50 non-synth just like the service manual dictates so I buy a 5 quart jug of that.  Service manual says 3.7L which equals about 3.9-4.0 quarts.


I put the bike on the center stand while it's still nice and hot and pull the drain plug.  I'm staring at the sight glass for about a full 5-6 seconds while oil is POURING out of the drain plug hole.  I figure, must be a stained sight glass...    NOPE.  After about 2 quarts of oil drain out, the sight glass starts to clear!  I drained all the oil out and collected it in a pan.... this pan was 11 quart capacity.  It filled the pan up to about 3/4" from the top (see picture).  I didn't have any empty jug to measure it, but I'd say there was at LEAST 6 quarts of oil in this bike.


I filled the oil up to a little over the center dot on the sight glass.  After sitting for a minute, it now reads maybe a bit more than 3/4 on the sight glass.


Then we had a monsoon so I couldn't go out and see how she does.  Rain in the forecast for the next few days.  I'll have to update on Saturday when it's supposed to be nice.


Thanks again!

[Chaos]

on another forum some guy filled an engine to the top of the filler cap :hehehe   It actually ran then immediately  threw a rod, probably hydraulic lock. 

[Laitch]

. . . on another forum some guy filled an engine to the top of the filler cap . . .

Amazing! Transposed gravitational osmosis isn't child's play!

[Arredondo1]

Im still putting my k75 back together. And I've only turned it on once to make sure the engine runs, and as soon as I saw a little bit of smoke I turned it off. Im starting to read that its a common thing. But where exactly is the smoke coming from?


I had my outdoor fan on and I was on the right hand side.Im pretty sure the fan pushed the smoke towards me from the left side, so I actually have no idea where it came from. I didnt want to mess anything up so I turned it off quickly. Do i just need to let it run and let it smoke all the Marlboros that it wants?

[The Mighty Gryphon]

Whenever the bike is parked on the sidestand a small amount of oil will seep past the rings to be burnt off the next time the engine is started.  Putting the bike on the center stand will prevent most of this seepage and the resulting smoke.

[Arredondo1]

Whenever the bike is parked on the sidestand a small amount of oil will seep past the rings to be burnt off the next time the engine is started.  Putting the bike on the center stand will prevent most of this seepage and the resulting smoke.

Ah ok, so smoke will randomly puff out from the block? I've had it on the side stand multiple times since its been in my posession, I will avoid putting it on the side stand from now on. Its still a long way off from being rideable but good to know.

[Laitch]

Ah ok, so smoke will randomly puff out from the block?

It should be coming from the end of the exhaust pipe or muffler, if your bike has one. Turn off your patio fan to find out.

[The Mighty Gryphon]

Are you sure it's smoke that you're seeing?  The shape of the block is such that it will collect water whenever you wash the bike.  When you run the engine the heat will cause steam to come out from under the air box.  As Laitch has said, if it's oil it will be from the exhaust unless you have a loose or missing exhaust system.

[Chaos]

and not randomly, just sometime on startup.

[Arredondo1]

Im really not sure where it came from, but I really hope it was steam. I'll be working on it later today and I'll record the startup so I can have a better view.

[Arredondo1]

So this is my first time I let it run for a good length and I searched for the source of the smoke. There's two small holes in the headers and another leak where the headers meet the exhaust. And smoke also coming from the exhaust.
Im just going to call this build the fog machine...for now, since i cant drive it yet. Really glad its not coming from anywhere its not supposed to. How long before it starts to smoke less and less?


Its a bit hard to see the amount if smoke in the pic, but it was a boatload haha. I have no idea how many years its been sitting.

[Laitch]

How long before it starts to smoke less and less?

What time is it where you are now?