Topic: Engine leak problems.

[ct_racer]

So I tore the motor apart... again...  I have a cb500 k2 and when I cranked the motor with the valve cover removed i heard air escaping.  If I understand an engine like I think I should...  I shouldn't be able to hear any air escaping the compression chamber if the valve cover is removed because no valves are open.  Unfortunately this is not the case.  The motor burns a lot of oil, but it has to be from the top end because the bottom looks great.  I assumed this was the valve seals which makes sense.  but if the cover is removed and I am hearing air come out the valve seals doesn't this mean there is an issue with the valve itself in the head?  I am still a rookie mechanic but am trying to decide what to do..  If anyone can help me out I would appreciate it...

Thank you
Court

[City Boy]

What is the compression like?If in fact u have compression leaking up through valve seals,the valves can't be sealing the combustion chamber and  or the valve guides are pooched! Good luck and Rock On

[ct_racer]

Ok, so I got the valves out and the new seals ready to be put on, but I am going to wait because my buddy is taking the valves for a solvent dip tomorrow.  The valves look great, other than being dirty.  The valve seals looked like they were in good shape except for maybe one or so...  What other possibilities could there be because she was burnin a hell of a lota oil and white smoke could be seen for a good quarter mile.

[City Boy]

Hi.The only other source of oil burn would be piston rings or blocked breather system.Was compression checked before teardown?White smoke is water vapour.  Rock On

[ct_racer]

Well it couldn't be vapor because its an air cooled engine.  I didn't check compression but I could hear air running past 1 or 2 of the seals.  However the cam was removed so the valves should have all been closed yet where I heard it was the valve seals.  When I pulled the plugs the 1, 2, and 3 plugs had oil on them...  I don't think is coming from the rings because the pistons had no pooling nor any scoring on any of the cylinder walls.  They shouldn't be leaking anyway because their brand new pistons and sleeves from the bore kit I put in.  If you have any other input I'd appreciate it, Thanks.

[City Boy]

Well sir,I can't offer anything further.I mentioned water vapour as u mentioned white smoke out exhaust.All internal combustion engines produce water vapour irregardless of cooling system type.White smoke is indicative of water vapour. Hopefully others will offer further assistance to u.  Rock On

[ct_racer]

Ya...  but this was just too much for that sorry.  Thanks for your help though.  Should have it back together in a week and we'll see how it goes.

[mlinder]

A compression test previous to disassembly would have been a good idea.

[bwaller]

 Since you have the head off it's best to change the base gasket anyway so pull the cylinders and check those pistons and rings..... Especially if you have oil fouled plugs & it smokes. Check all the fire rings on the headgasket for a blow-out spot while you're at it.

How many miles on the new top end? Are these the flat skirt 61mm pistons? (605 kit) Seems there have been problems with these rings before.

[ct_racer]

Only about a mile on the top end... It's smoked since it was back together and hasn't been good enough to take on the road. 
i checked all the gaskets but not the rings, everything down there looks good.  All the o rings are in place.  I've got the old seals off and I'm gunna take it to a machine shop to have the seats reground to make sure the valves seated good.  I was gunna have those dipped too.  What kinds of things should I be looking for?  Also what can i do if I need to replace them?

[ct_racer]

Well, just dropped the head off for a valve job so should have it back in a couple of days.

[ct_racer]

Ok, so got picking the head up tonight, however I apparently was missing the washer for the inner spring on one of the valves and apparently I lost one of the little green orings that goes between the jugs and the head.  Would anyone know where I can get these?

[ct_racer]

Ok... So when I got the head back I was told it was missing a valve shim so I ordered one and a couple other parts which took 3 weeks to come in... .   So, I got it back together today and she fired right up...  Still burns oil.  Now what?

[ieism]

Well, if you've just done the topend i'm not surprised it smokes a bit at the first few startups.

The parts need to seat, and it's probably burning assembly lube/oil too. What colour is the smoke now? Still white?
These engines can smoke from watervapour a lot, especially when it's cold.
Have you done a compression check yet?

[ct_racer]

Oh right, I forgot to mention the smoke is more blue...  I just ran it and the top end it real loud.

[ieism]

How exactly?

Is it knocking? Or ticking? Or rattling (as in camchain noise, they all do that).

Are you sure the headers/gaskets are airtight?

Did you set the valveclearances ok. Do a full tuneup and a carbsync?
Can you crank it over with the kickstarter using just your hand?

Does the oil light go out when you start it?

[ct_racer]

It seems to be knocking and rattling but the oil light does go out.  I think I will do a full tune up tomorrow as one of the carbs is leaking as well.  I will go through and check everything then see how she does then.  I'm just glad the thing is back together at this point.  On the chance that it is piston rings (which is getting more and more likely)  does anyone know where I could source the rings.  Its a cb500 with a 605 kit and I believe it has 61mm pistons (Henry Abe kit).