Need guidance diagnosing no-start symptoms

[LoHo]

Okay, no clearance on #3 exhaust valve...whew. When it ran there was a hollow pinging from that side, probably the meager combustion being pushed through the open valve. That also explains the backfires, as collected mix occasionally blew through the open exhaust side.

At least I know how to fix that.

[skids]

good running bike = spark, fuel and air, compression!

Gee wiz LoHo! Git 'er done.

[LoHo]

Skids, if my goal were to have a good running bike, I'd have someone else work on it. I'm not as dumb as people say, mostly.

[DGXSER]

I'm not as dumb as people say, mostly.

If I were as dumb as my teenage son thinks I am it would be a miracle I breath.

[LoHo]

Okay, the #3 clearance was .003, not zero. Would being that tight result in reduced compression? I know that that means it closes at least a bit, but would that reduced closed interval kill compression?

[LoHo]

DG, as Mark Twain said: "When I was fourteen, my father was so ignorant I could hardly stand to have the old man around. When I got to be twenty-one, I was astonished at how much the old man had learned in seven years."

[motoman]

Okay, the #3 clearance was .003, not zero. Would being that tight result in reduced compression? I know that that means it closes at least a bit, but would that reduced closed interval kill compression?

Closes all the way, just a bit tight for heat expansion(thought U were smarter...lol), just being on the tight side changes lift timing a bit..........might wanna go back thru ALL those clearances and check them again. By that, I mean double check your cam lobe locations when checking clearances and shimming. No offense Larry, but makes one kinda question your procedure to have zero clearance on said shim, then .003.............BTW, your rally breakfast WAS the bomb.......and I'm definitely not making any points here......

[crazy steve]

Okay, the #3 clearance was .003, not zero. Would being that tight result in reduced compression? I know that that means it closes at least a bit, but would that reduced closed interval kill compression?

Yes it will.... My XJ when I got it was like that; several valves down to under .004". One cylinder almost tripled in compression number with a valve adjustment....

[LoHo]

Thanks, Moto, what I meant was that #3 was way too tight for my make/break gauge when I first looked at it. Careful measuring revealed the .003, as I went through and checked all of them methodically. My first exaggerated post was relief that it was a tight valve and not something worse.

Feel free to question my feeble skills anytime. Cold oatmeal is a wonderful breakfast and good for you, too.

[LoHo]

Man, I don't even want to tell you what I did to my bike...

[BA80]

Hmmmm.........that can't be good.

[skids]

Are you embarrassed about it??? Now we really want to know LoHo. (Hope your bike is OK)

[GLoweVA]

Man, I don't even want to tell you what I did to my bike...

Come on.... I'll tell you about my classic mistake:
"I went to swap the heads around from my G to my SG and I ended up putting the cams in the wrong spots. Had them all torqued down and tried to rotate to get the cam sprocket bolts in and it wouldn't spin. I paused and then I saw what I had done. Thank goodness I didn't mess any of my valves up doing that. I was lucky!
Oh, and during all that, I dropped a cam cap nut into the cam chain valley! I should have stuffed it with paper towels! I ended up fishing it out with a piece of wire."

So tell us what you did, we've all done something we're not too proud of, but that's how we learn from each other.

[LoHo]

When I started going through the valves for shim adjustments, at one point I aligned the dots on the cams with the arrows on the cam bearing caps...spot on! Then I looked at the crank, which was right on the mark...the C mark. I guess I spaced out a year ago and did the C rather than the T. The bike cranked fine and this never revealed itself until it tried to run.

I loosened everything up and did the timing correctly. However, when I turned the crank by hand, I hit a spot about 160 around that resisted. I couldn't see a valve in the way, and didn't hear any contact, but I stopped anyway. I realigned everything several times and encountered the same resistance each time.

I took the cams off all the way and blew into the cylinders with the valves all closed. #3 flows freely, #1 and #2 seem to flow slightly, and #4 seemed tight. I can't remember If I bought a new head gasket or tried to make a go with the old one last year after I changed the valve oil seals. I think I bought a new one, but I can't find the old one, and I doubt I would have tossed it.

I will hook my compressor up to each cylinder and see if I can find where the leaks are. The intake valve on #3 was way out out of spec (.457mm), so I must have bent that one a bit. The ringing/pinging I heard when she was running must have been the cylinder dinging that valve every revolution. I wonder if that valve was originally a bit tighter than the others which resulted in it getting into harm's way.

Off with her head!

[GLoweVA]

Last year, When I first took the valve cover off my SG project, My #3 exhuast clearance was way up there too. Then I found that it had little to no compression. (Bent Valve) got a new one in there and I should have lapped all the other valves while I had the head off, but alas, I did not. Now, that head is off again, while the G head is on the bike so that I can do just that.
I may end up doing the piston rings too, I haven't pulled the trigger on that just yet. (that's an all weekend job)
Too bad, my bike is my commuter, so I have to have at least one of them up and running.
I've 'borrowed' too many parts off the G for the SG, so he won't be running anytime soon.