Any ideas on where I went wrong?

[DJinNH]

As some of you may have read, I was working on a head gasket replacement. I had everything going pretty well or so I thought.

Last night, I finally got it all back together, new head gasket, yet another new valve cover gasket, scrubbed the oil off my exhaust pipes and remounted them.

Then the moment of truth. I advised my neighbors that if it didn't start up and run right, go inside and lock the doors and windows.

So I turned the key, hit the start, the engine turned for a second, then...tap, tap, tap, a loud metalic sound coming from the left side of the engine, probably upper left but I didn't keep trying it as I was afraid of causing more damage. Once the tapping sound started, the engine was no longer turning over.

OK, no sugarcoating....how bad did I screw something up? I tried hard to follow along with my repair book. I'm suspecting a rocker arm or something. Again, I am a novice mechanic. The only reason I suspect rocker arm is that one broke on a large engine for a speedboat I was running years ago and I remember that sound. Seems to me roughly the same however with that boat, the engine ran, just had a very loud tapping so I secured it ASAP.

Any chance it's something else...please say it is something simple? Oh that's right, I asked for no sugarcoating. Damn!

Don

[trbig]

So.... no turning over and the bike's been sitting.... are you sure the sound wasn't coming from your starter? (Weak battery)

No rocker arms on these bikes.


Tod

[DJinNH]

Nope, the bike "was" running fine, I just had oil leaking from the head gasket in the front of the engine so I couldn't put off replacing the gasket any longer.

The battery is new and charged up. I just topped it off with a trickle charger a couple of weeks ago.

Here's exactly how it went in as good of detail as I can give;

1. Key on, hit the starter
2. Engine turned over for about one second, then the tapping started and the engine was no longer turning over.

That's it, I tried adjusting the chain tension device on the front of the engine, below the exhaust heads. Tried restarting it...tap, tap, tap from somewhere on the left side of the engine. Only tapping, no turning of the engine. It's a fairly loud tap too.

Don

[The Lorax]

Hopefully I am mistaken, but the description of what is going on combined with the description of what you were doing makes me think that perhaps one of the cams were not lined op correctly and valves have been bent. the engine not turning over is bothering me some as I don't think that bent valves would keep the engine from turning. pull the plugs and turn the engine over. see if there is something in the combustion chamber is stopping things from moving. otherwise possibly something that fell down into the engine while the head was off, or possibly something has fallen out of place and is wedged between the crank and the case. it could possibly be the starter motor (unlikely) or perhaps the starter clutch (also unlikely). drain the oil and pull the oil pan, look for broken bits in the pan. this is all speculation at this point, until more information is available or someone who has had a similar issue chimes in with a potential solution, all we have is speculation. take your troubleshooting one step at a time, try and understand why the engine isn't turning. hopefully it's something simple, maybe, maybe not. could be a mistake you made during assembly, maybe not. only way to find out is to troubleshoot with a clear, emotionally detatched mind. find the issue, fix the issue. how hard can it be? point is whatever is going on, take your time, troubleshoot the issue in a calm collected manner and I'm sure you will be successful. hopefully, again someone with more knowledge will know what the issue is and help more than my inane ramblings will. anyway, keep at it, you'll find it, I have faith in you. have a nce day and ride safe

P.S. check the gear on the starter, you never know, could have stripped (again, unlikely)

[Gyrogearloose]

Hmmm, I'd pull the valve cover gasket and check the cam chain, sprockets and cams for starters. Oh, speaking of starters...no problems in the recent past with starter? Keep us posted.

[Gyrogearloose]

I meant valve cover, not the gasket...ooh, to early in the morning.

[DJinNH]

"Emotionally detached mind" ya, do you realize what you are asking of me? Obviously, you don't know me very well.

I agree with you though. I keep telling myself to walk away from it for today but it keeps calling my name. I hate the fact that I have worked my butt off on it and came up short. I'm a little too bullheaded to ignore it now.

I'll go ahead and pull the valve cover and get back to you guys on what I see. I just may have some problems typing through all the tears.

Don

[TADracer]

Sounds to me like your cam chain skipped a tooth or two. If this happened then your cam/cams are instantly about 13 degrees or so retarded and that is receipe for a piston/valve collision especially on the exhaust side.

A check is fairly easy to do. Take valve cover off, plugs out, timing cover off and carefully rotate the motor clockwise until you either feel something or you get to the T mark on the timing wheel. If you reach the T mark without incident then check that the dots on the cams are in line with the arrows on the center caps. If not, then you have your answer. If they do line up then your prob is elsewhere.

[DJinNH]

OK, I'm going to try to explain this even though my terminology is a joke.

I took the valve cover off and can't see anything that looks damaged.

I've located the source of the loud snapping sound. When I rotate the cam and each cam rotates down, as they come up, that metal disc below it is popping up with such force that it splashes oil and I hear that loud snap (metal on metal). I noticed as I rotated the cam, that snap sound would come from each one of those discs that had just been pushed down. Again, it only snaps when the discs pops back up.

My timing chain seems really tight, any chance that is the problem?

No broken mounts for the the cam, no metal chunks or flakes visible.

Don

[DJinNH]

Just to add....me and a friend are tossing around ideas.

When I was putting the cams back together, we did not secure the mounts when I was rotating the timing sprockets to allow me to put those two nuts in each of the sprockets.

He thinks that by turning it without having the cams secured, my pistons are not in sync with the cams.

Sound about right or at least a place to start looking?

Don

[The Lorax]

There are dots on the camshafts which are supposed to line up with arrows on the journals (upper bearing caps, whatever they are called). consult your service manual and check where and when the timing marks are supposed to line up. dots and arrows, "T" or "C" I don't remember at the moment, it sounds as thought you may have bent some valves. read through the procedure carefully and follow it to the letter when you are setting the cam timing up. bad things can happen otherwise. if it's just bent valves, chock it up to experience and replace them. remember, it can fe frustrating, it can be expensive, but almost anything can be fixed with a little patience and time (and of course some money). hope all works out for you, don't get discouraged, you can fix this, whatever it turns out to be. have a nice day and ride safe.

P.S. emotional detatchment, where it can be extremely difficult, is paramount to keeping a clear head and diagnosing and repairing a problem with anything. especially when it is something as near and dear to one's heart as the motorcycle can be. find a happy place, find the issue, and eliminate it....simple right?

[olebiker]

Sounds like you have bent valves that are hanging up . If that disk you are talking about is on the top of the valve stem. Follow the advice to line up cam timing marks.

[CarolynS]

finally something I know...

The mark where the dots line up is the 'T' mark for checking the cam timing.
I am going up to Ed's to drop of the valves for my bike. I have extras if you need them, or if you want a hand this afternoon, I will be in Pelham, NH and can swing by, but I'll be leaving soon. Leave me a number and I'll call you.

[DJinNH]

OK, back again. It seems like we have the cams all lined up correctly now so the open and close in coordination with the pistons coming up and down.

BUT....should the timing chain be extremely tight? When we try to turn the cam, it is very difficult and it just seems like the chain may be binding or something. Could it do that.

OK...my buddy just walked in and said it is turning much easier now.

So now I am praying everything will be OK with the valves. Like I said, at least the loud snapping has stopped completely.

Thank you all for the help so far. You all are awesome!

I'll get back to ya and let you know how it all turns out. Back to the parking lot...

Don

[saddle up]

Sorry Brothers

But this kinda crap that makes me real lazy. If it's running good, don't mess with it. If the noise is too quit on the top end then you gotta worry. If it's making noise you don't have a problem. I tend not to dink with a perfectly running engine. I have bent more valve's putting in a top end, i.e. changing shims, changing cams etc. albeit not exclusively Yamaha. All the motors from Japan where copied from the Kawasaki 900, which was a copy of the Porches I believe. Our bikes are the same as solid lifters. No noise=problems, noise= no problems, at least you won't burn a valve... :rolleyes
You might round off the cam lobes after 200,000, but these are tough cams and tough bottom ends.
Please correct me if I am wrong...
P.S. New Hamshire, I am not belittling your problems, I sympathize with you very much. I am just putting in my probably worthless .02 cent's in.
I got a complete 79 head if you want to switch over....