'86' V65 Magna build

[ToolBoxPop]

Sooo... "Who's on third?"   

[TLRam1]

What puzzles me about this is the plug was always dry on this cylinder, not saying compression is not part of the equation but I would think the plug should have been wet unless you had very little vacuum.

Not to damper your will or enthusiasm by any means, I would have diagnosed this a little further before a tear down, since you are here I would make sure all is okay before going back together. Understand I do like your get-down-to-business approach.

Someone mentioned a ring, how does your cylinder look for the problem area?

[hootmon]

Tool..
Didn't you mention that the compression was the same with and without oil, OR did you ONLY test with oil?
IF tested dry & oiled, doesn't that say it's probably NOT rings?
Just trying to not go deeper into the motor if not necessary..

Did you consider taking the head to a head shop??

[Jigger]

If he has a broken compression ring. Wouldn't he have seen some type of blow by coming from the engine ? I don't know much about these engines. But do they have a vacum line going to the grank case to create  negitive pressure ? If so wouldn't there be a lot of oil residue inside the line?

[silveradocowboy]

Did the head gasket show any signs of leakage?

Make sure the spark plug screws in securely.

Valves...
Try spraying some WD-40 or such on top of the valves(from the carb and exhaust pipe sides) and see if any of it seeps through. It's hard to tell from the pics but it looks like one of the #2 cyl. exhaust valves might leak.

[dgc67]

If he has a broken compression ring. Wouldn't he have seen some type of blow by coming from the engine ? I don't know much about these engines. But do they have a vacum line going to the grank case to create  negitive pressure ? If so wouldn't there be a lot of oil residue inside the line?

Did the head gasket show any signs of leakage?

Make sure the spark plug screws in securely.

Valves...
Try spraying some WD-40 or such on top of the valves(from the carb and exhaust pipe sides) and see if any of it seeps through. It's hard to tell from the pics but it looks like one of the #2 cyl. exhaust valves might leak.

Just re-emphasizing what sounds like really good advice to me.

[ToolBoxPop]

Before teardown I did check the compression with a splash of oil and dry. Both only read around 90, which is terrible.  There was never blow by burning out the exhaust.  The spark plug was changed twice, just to see if a simple thing would help and it didnt.  I know at least some amount of fuel and spark were getting to that cylinder because I pulled all three other plugs and left that one on and cranked it over.  It sounded terrible but the bike certainly was trying to start.  It would fire kinda randomly but at least I knew that cylinder was doing SOMETHING.  I started by just pulling off the valve cover and checking the clearence.  The #2 was sitting at .005 when the book calls for .006 so I made the small adjustment.  Now this whole time I did still have a pretty terrible gas leak from the tube that connects the #2 carb to the #4, but I could pull the #2 float bowl screw and gas would pour out, so I know gas was getting down there.  When I pulled the head off the head gasket was bone dry with no signs of any compression leaving that cylinder.  I know the #2 valve heads are pretty built up with carbon on both the intake and exhaust while the #4 exhaust valves look heated and browned, so there is certainly a difference there.  I took the whole bike with all the parts neatly aranged to a shop yesterday to see if he could make top from bottom of this problem.  He won't be able to start till Monday, though, so now I'm overly anxious and restless lol.  I don't like letting other people work on my stuff, but I feel like I'm out of ideas.  Now he did say the first thing he's gonna do is pour some fuel in the tops of the valves to see if it leaks through... I noticed silverado just mentioned that.  Such a simple idea, I wish I would have thought of that before I took it in.  So now, sadly, I just wait

[roboto65]

Well keep us informed of the outcomehope it is something simple..

[ToolBoxPop]

Well, after about a week and a half, I was finally able to get some time to work on the bike again.  I pulled the left front exhaust valve out first and it was really badly coated with carbon build up around the underside of the valve head but not really too bad on the seal itself.  The mating surface on the actual cylinder head was equally coated on the inside, but again not too bad on the seal surface.  I cleaned it up to look like new and replaced it.  the springs, cap, and retainer clips all looked perfect.  I then pulled the Intake valve directly adjacent to that exhaust valve and that's as far as I've gotten so far.  The underside of that intake valve has two pretty deep portions erroded into it but the mating surface seems completely intact.  The intake port on the cylinder head looks a bit dirty but no damage on that side. 

I wonder if that damage could cause a compression problem or not?

[Greg Cothern]

It could... 
Wouldnt take much keeping the seal from being proper to hurt compression #'s.  If you dont mind doing the work, clean all the valves and heads up, reinstall and check compression again.  Might be all that is needed.. 
I would still (personally) refresh things up since I was there.  Seals, gaskets, rings, hone, etc.  Improvements as one desires etc.

[John Luttrell]

It could... 
Wouldnt take much keeping the seal from being proper to hurt compression #'s.  If you dont mind doing the work, clean all the valves and heads up, reinstall and check compression again.  Might be all that is needed.. 

Yep, I agree, since he got the same PSI on both the dry and wet compression test, the problem is either a bad head gasket or a valve; being he said the gasket was good, that only leaves the valves.

[ToolBoxPop]

I now have all of the valves and the head super clean.  I got the head assembled and the new head gasket on and the head lightly bolted up to the crank case.  I've got the confusing set up with the chain tensioners attatched and I'm now completely terrified to finish it all up lol.  The book does not describe in clear detail how to have the cylinders sitting in cunjunction with the camshafts and sprockets.  I know how quickly this can all be for not if I button this thing up with the cams in the wrong position.  Gonna take a breather till tomorrow then tackle it again.  Thanks for the input to all so far who have helped me out.

[silveradocowboy]

Not sure which book you have but the Clymers manual that I have is confusing also.

At the T 1-3 mark the #1 cam lobes will be pointing each other.

At the T 2-4 mark the #2 cam lobes will "slightly" facing each other at about a 1 o'clock and 11 o'clock posistion.

If I recall correctly when at the T 1-3 mark all the lines on the cam gears will line up even with the head surface.

[ToolBoxPop]

oh boy, I can tell that my cams aren't lining up correctly.  When I have it at T 2-4 The lobes over the #2 are at about 1 oclock on the forward side and about 2 oclock at the exhaust side.  I have the rocker arms loosened all the way up and plugs out and I can turn the motor by hand very slowly and when I get back around to the T 2-4 there is no compression when I put my finger in the plug hole.  There are a set of sprocket dots at 12 oclock at T 2-4 and the sprocket lines are somewhere 90 degrees back from that, nowhere near lined up with the line of the head.  I just can't quite understand how the cams could go on in any other way.  When it's at T 2-4 there should be no pressure on the valves to the #2 so it eliminates almost any movement where the cams could be rolled forward or back.

[ToolBoxPop]

I got the bike all put back together yesterday.  I read out the compression: #1-185psi #2-195psi #3-185psi #4-190psi.  So now there is no question about compression!  I took the carbs apart and cleaned all of the jets and float valves.  the #2 carb had some pretty bad sandy looking residue in the bowl but the jets and float valve were clean.  I checked the spark at all four cylinders and it's all sparking really strong.  I set the valve lash to .006 like the book tells.  I start the bike up and it fires right up on the first crank.  The exhaust note seems quite a bit deeper than before which I thought was a good sign.  I give a few minutes of idle time and give it some throttle and it's still exactly the same as before   I shoot the temperature with my little temp laser gun thingy and the #1,#3, and #4 are all around 250 degrees and the dang #2 is only 90   I quite litterally do not know what else to do.  Why on earth would that cylinder still not be firing correctly?  I have a quad vacuum guage set coming in the mail in the next couple of days and I'll read out the carbs then, but as of now, I'm at my witts end.