Hi,

I recently installed new piston rings in my 1989 K100RS.

The reason was low compression in cylinder 4 (120psi) and avrege 130 psi in the rest.

When enegine head was off i sent it to a pro to treat the valves and to change the valves oil stem seals.

Before i did the change the bike wasn't burning any oil.

After i rebuilt the engine the bike started and engine works smoothly except it heavilly burns oil during accleration.

compression in all 4 cylinders is good 150psi

When pistons where out i visually checked the cylinder for wear of the nickaseal

coating and it wasn't shown with an unnaked eye,also when putting a new ring inside the cylinder to search for signs of ovalness,ring fit nicely and no light was passing through the gap between the ring and the cylinder wall.

i'm telling all the story since i was told by a local bmw dealer that this models when reach high milage tend to get oval shaped cylinders which causes the problem.

i'm about to take the engine head off again hoping the problem is from that area maybe an oil seal from one of the valves?

Any ideas ???

Did you hone the cylinders before you reassembled the engine. Even a Nikasil bore needs to be honed to make the rings bed in.

no i didn't hone the cylinders.

can i hone them now after i put around 1000 km on the engine?

You would need to pull the engine apart again but I would do it because as you can see by the smoke it needs fixing and it is highly unlikely that it will be rectified if left to its own devices.
There are some methods that are used to seat rings but none that I recommend as most can and often do have disasterous results.

I am not doubting your experience in these matters Rick, but i didn't think you could hone nikasil lined bores.
Just going by Japanese bikes though not K bikes. Interested to know your experience on this. Always good to learn something new hey.

Nikasils, in both Airheads and the Mighty K, love a good hone out...they respond well to it and will go for another gazillion kilometres. The oldtimer mechanics at the workshop recommend a flex ball hone as best for them too.

Thanks for that TWB, i new i couldn't trust those Suzuki techs at that place i used to work .
Makes sense i guess as it would help enormously for the bedding in of the rings, particularly the oil control rings.

caferacer62 wrote:I am not doubting your experience in these matters Rick, but i didn't think you could hone nikasil lined bores.
Just going by Japanese bikes though not K bikes. Interested to know your experience on this. Always good to learn something new hey.

The bores will wear just enough to polish them and that can take 200,000k and if you fit new rings there is a good chance they wont bed in.

I have never honed one and with the airheads always send them to get a pro to do it. apparently they are very fussy as to how it is done or it holds too much oil or wont hold enough.

First experience I had was when I did the rings on the R80 at the 100,000 mark as per the manual and it just kept using a bit of oil, nothing real bad but it used almost none previously.
The bore was polished a tiny bit at the top but not enough to be able to measure.

I know one guy that used to chuck some kerosene down the plug holes then turn it over to push it past the rings then start it. He reckoned it worked.

I have heard that BMW has changed the way the bores are done in the last 10 or so years so maybe maybe they are following the way the Japs are doing it. The early Rs used to get problems with the nicasil peeling off mind that is 30 years ago.

Makes sense to me Rick. We had a DR650 when i was at the bike shop, that they had honed before rebuild. It then used heaps of oil, the head tech stated that you can't hone these new bores now. I asked what was the option and was told the customer would have to get a new barrel.
I know the motocross guys i knew used to send there barrels to germany to get them Nikasiled. Apparently they are the best at it.
Which makes sense as to the fact that we can hone ours for a rebuild.

Old Fred the former helicopter mechanic used to run a flexy hone through them very lightly with running hot water. I've watched him do it and they seem to bed in and last.

One thing that I didn't say is that they have to be cleaned very carefully because the bore holds the grit from the hone and I am not sure on this but I also believe that the finer the grit on the hone the better.

Yup my bro in law is an old skool diesel fitter and mechanic and he used to do upper cylinder lube and and de carbon on older engines with a beer bottle full of a combo of brake fluid, water and ajax. Hold the throttle wide open and slowly tip it in. Used to smoke like hell for ten minutes and then come clean.
If i hadn't seen it i wouldn't believe it. It worked though.

from your discution i understand that honning might not work since there is no guarentee that the rings will bed

what about sleeving reboring and matching a new set of pistons and rings?

thanks;)

All of the above is good info for reference but i would like to ask Shay ..... how many miles /kms has this beast done ? The reason i ask is that your quoted comp's aren't that bad given that the measurements are more comparative than absolute values .
OK .. you've put new rings in ? in my opinion prematurely! So what would i do ? Run "her "in , give it some time , multiple short runs building up to longer rides , monitor smoke and oil consumption , she'll bed in i reckon , better than a ball hone anyway!
Anyway , how many miles kms on this motor please ?

well,when i bought it showed 120000k on the clock but it wasn't working so..

i did speak with the last owner that swore that the clock was working when he bought the bike and he didn't add more than 10000k on it (he didn't even use it for two years before he sold it to the dealer),so including what i added on it there are no more than 140000 on the bike...

That's Sweet F... All as we say here in OZ ! Kms that is . These motors need serious neglect and outright abuse to need ringing at that kms .
Try what i said above , run her in.

I will try that,

thanks for the input

I have currently been talking to a guy in US about his K75 which was down to 45psi in all cylinders after 92,000miles and I have heard of then chucking the towel in at a lot less. Just because some go to 800,000 miles does not mean that one should not need rings at 150,000kms.

Good point Rick , i should'nt have questioned the initial need to re-ring 'cos it's done so apologies for that .

I know that the nikisil is hard as the bulls forehead so needs help to accept the new rings. All i'm saying is don't throw good money after bad . Another stripdown and associated expense is questionable , they are not that precious or valuable , we dont have to save every one do we?

How embarrassing is the smoke Shay ? That would be my criteria , do you use the sidestand ? Run it some more and only use the center stand .

My approach is always the path of least resistance like water and electrickery , if it does 'nt come good, junk it , plenty of motors out there .!

Guys, I have a rarity in that my 1985 K has only 68,000 kms on it.

Mine smokes like a diesel freight-train on a cold start if I use the side-stand.

That bugs the crap outta me, but I'm not gonna tear it down to try & fix that cause I'm not sure I can.

Given that in 1985 the owners manual stipulates it will smoke some on cold starts.

So, what causes that, and is there actualy an affordable fix other than using the center-stand?

Not trying to high-jack the thread, just throwing in my $.02



Rick

Yes Rick , later piston s and pinned rings but your in Shay's dilemna then . Just ride her and use the center stand for those clean exits .

Rick don't be too concerned about the plentiful smoke, it is a common problem with Ks and we have learned to live with it and laugh about it then deny that "mine would do that".
It is caused when left on the side stand when still hot. The oil drips down into the bores and seeps past the rings into the combustion chamber and then starts fogging for mosquitoes on start up. Most engines have a favourite position to stop and if that position is with an exhaust valve open on the cylinder that gets the drips then the exhaust pipes get a good dose of oil and that causes a heap more smoke and that may be what yours does.
On later Ks BMW pinned the rings so they couldn't rotate and get the gap down which made the problem worse. This pinning did not really solve the problem and both my Ks smoke if given a chance.
Parking it on the center stand can help and holding it leaning over to the right for 10 seconds after stopping can also help.
I know of quite a few who always park on the center stand.
I would suggest doing what most of us do when it happens just stand there with an inocent look on your face and say what smoke or say the mossies wont bother you now , smile and ride away leaving a trail of smoke while laughing.

shay wrote:I will try that,

thanks for the input

One thing I will suggest before you do anything else is to take it to a quiet road and really give it to it.
Hard acceleration at low revs in 3rd 4th and 5th from 3000 to 6000 and back of and do it several times in each gear.
This will push the rings out hard against the bore and may start the bedding process.
Ride it a bit more and see if that works, it very well may.
When I worked for Honda Australia we quite often got warranty claims of blowing smoke and excess oil consumption with a new bike and we would get the customer to leave it for a few days and then ride it everwhere we had to go and ride it hard. More often than not it worked and all was ok but we never told the customer what we did. We often told them that we used a very low grade of oil and it didn't lubricate well so let the rings bed.

Well,the smoke is quite embarresing.especially during acceleration around 3000rpm where it's as if someone purred the oil straight into the exhaust manifold.

I should say that during the first 500k's after engine reassembly i added about 1 liter of oil(!) after each short 100k drive!! last 500k's it seemed to burn less(around half the amount) although i didn't monitor the quantities accuratly.I agree with the "no point spending good money after bad" argument,and i would have started from the engine replacing solution in the first place ,my problem is that buying an engine on the internet is one thing but shipping it all the way here doesn't make any sense.I might as well buy another bike...

so i think i will go for the running her in embarresly smoking solution

i should start practicing my innocent face

smoke out the back??? i call it "just marking my territory "

happens about 3 in 10 sidestand parks after being hot ....

i agree ...give it a good "fang "...in safe enviroments ...and really load it up .....a good long hill is also a recommended place to take her to the limit and cure those oil issues ....why not ?...nothing to loose

Another thing to check since the "new" compression figure s are 150, is the crankcase breather . I am not familiar with the system on these engines but someone will know and maybe chip in .