Still burning oil after rebuild

[Anonymous]

:? I have a 79 GS1000 with 55,0000 miles that was burning oil, so I did a rebuild by sending out the cylinders and head to a very well known bike shop where they bored and honed the cylinders to match the new 1085 weiscos. New valve guides, guide seals and a valve job was done. New cam chain, cam chain tensioner, and cam timing was done. Seemed like a complete rebuild to me that would cure my smoking on de-accelaration. It did not. Plugs do not show any large amounts of oil burned, - all a little dark due to rich idle curcuit. (29 smoothbores). The only thing I can come up with is maybe to much side play in the old bucket/tappets. Could this be causing the valve stem to have to much horizontal movement for the valve guide seal... or am I reaching? Possible small crack in cylinder head ??? What did I miss ?
The Becket burner it was, still is. The first 500 miles on this rebuild burned a quart of castrol 10/40 oil. ahhhh.... take it apart again ??? ..

Ok, I'll take any comments now...Thanks, Moto

[argonsagas]

Usual advice after that much work is to take it easy on the RPMs and power use for at least 500 miles. Then dump the oil and filter.

Did you do that or did you run it fairly hard?

The engine does have to go through a break-in period again, but, for that distance, a quart seems excessive.

Your rings may still need to seat, especially the oil-rings...the valves should all be good, and have no leak at all.


Try running a compression test AND a leak-down test on it.

[Anonymous]

Compression test showed approx. 150 on all , did not do a leak down test. The break in was easy, stayed under 4,000 the first 200 miles and have not gone past 7 yet. I did use a lot of on/off throttle , but kept the revs down. Moto machine shop said not to baby it to much.... Guess i'll give it more miles. Thanks for the reply !

[saaz]

Give it some more break in time. With all that work you should have no problems if you have not broken a ring when installing the pistons. Been there, done that myself!

[Anonymous]

Did you make sure that the rings had an overlap when installing them?

[brs127s]

I recently rebuilt the top end of my 850. Had the cylinders professionally honed, replaced the valve seals, etc. I have a little over 1400 miles and used about a cup of oil. My exhaust is dry, and the plugs look perfect. I did the break in period according to what the owners manual specified(after all, its a "new" bike). I was advised to give it more time. Oh yeah, I forgot, I did have a slight oil leak at my oil pressure switch. Hopefully I cured that last night by rerapping the threads with teflon tape and reinstalling it.

[Anonymous]

Motoderf,I must say I have a real problem with people saying you
should baby an engine after a rebuild.
True,at first you should let the valves/guides lubricate and get the high
spots worn down but then roll on the throttle!
Piston rings have radial pressure built in them otherwise an engine
would not start.The rest of the radial pressure is from combustion
pressure.Combustion pressure seeks the path of least resistance.
In order for rings to seat properly they should be under positive
pressure situations.This can best be achieved under wide open throttel
situations.Take the bike out and flog it,do WOT for 30 sec.then close
throttle,do it again,run the gears at WOT,
flog the cr#p out of the engine.Hopefully its not to late.
Believe me, my friends and even my wife say I drive like an old lady,
but during break in you got to give it hell.
Tim

[Anonymous]

Popskulll,

Thanks for the reply ... I tend to believe your thoughts on this ..
I am presently waiting for a new tappet / bucket in the mail, as one of them is too worn for my taste. After I replace it and check the valve clearance I will run it hard as you suggest. I should know by the end of this week if it will be "tight" ..... Thanks ... Moto !

[Anonymous]

My opinion, don't baby it, but certainly don't abuse it. But mainly, don't keep it at the same rpm for an extended time. Wind it up thru the gears a few times, but don't over do it. Also try 20W50 oil, I had a new 1000 G in 1980, that was using a qt. every 700 or 800 mi. My dealer said this was not a problem the warranty to cover, he suggested 20W50, & it helped a lot more than I thought, it then would go apprx 2000 mi on a qt.

[Anonymous]

I probably will be unpopular for saying this, but if you put the cylinders on lubricated with a modern oil with additives, your're sunk. You'll have to take it apart again. The oil rings will never seat. The compression rings have already seated due to the fact that they had their oil burned off in the first few seconds of running. The oil rings are a different story. They have "Z-7" or whatever keeping them from seating. The only way I have ever got rings to truly seat correctly is to put cylinders on DRY. Yes, unlubricated! The only thing I oiled was the piston pin. Rings, pistons and cylinders were without oil. Don't worry, I'm not a madman. The crank will start slinging oil up in there soon enough upon starting. I the meantime, everything beds in nicely, and you can ride normally. I've had many years' experience with this, and your free to let things go as they are and see if the rings seat on their own. Please get a number of opinions before you do anything. All I'm saying is this approach works for me.

[Anonymous]

to talkinboutshaft

I have heard that said before about assembling rings dry. Although it goes against the grain of how an engine does not eat itself, it does make some sense. With this in mind when I picked up the parts, I had asked this well known drag race engine builder about the assembly.. and they said use oil. for now... i dunno.

Time will tell.

8O

[saaz]

Ok, look at this for one opinion

http://www.mototuneusa.com/break_in_secrets.htm

alos lots of other interesting stuff

[Anonymous]

Very interesting stuff.... Thanks Saaz

[lhanscom]

I'm still trying to figure out if that guy is a crack pot or not. Unfortunately I don't have the time or money to test if he's right or wrong. Very interesting site though.

[Anonymous]

Live and Learn from this..

Back in September I wrote about how I was burning oil after a total rebuild, well the mistake is all mine. I tore it down again this year and found I had overlapped the expander on the oil control ring on # 3 cylinder. I could tell this because one of the end tabs on the expander had worn away... gone! I replaced this expander, did a quick scuff hone, reassembled it REAL carefully and now all is tight with an oil free burn. What really thru me off on this last year was the rich carburetion from the 29 smoothbores which had the plugs too dark to read the small amount of oil being burned, or ... could it be my lack of experience on this???

Hope my trials on this helps someone else out.

Moto