Need timing help

[tarzan]

So I just got done checking valve lash and timing.
Here are a couple pics of timing as it sits.




So it looks like maybe timing jumped?
I am getting air coming back through #1 carb and the plug fouls quickly.Also producing some popping.
Should I re-time the cams or should I be suspecting a bent valve?
Thanks. Rick

[skids]

Hmmm... Maybe it jumped a tooth on the crank sprocket, but the the cams are in synch with each other. You must have turned the crank to line-up the dots on the cams, so if you didn't feel any interferrance, you can check to see if top dead center is in line with the T-mark or if that needs some adjusting there. If you bent a valve, there are two possiblle indicators. One is that you will measure excessive clearance at the shim, and the dead giveaway is that you suddenly lost compression in a cylinder.

[tarzan]

No, I havent run a compression test yet.And the valves are tight.
#1 I=.152mm E=.216 #2 I=.152 E=.229 #3 I .152 E=.254 #4 I=.165 E .229
So it looks like the valves need adjusting.
So could the crank jump a tooth like that or would the cams be out of whack from each other usually?
I will go ahead and check TDC with the pointer and see what it looks like.

[blue giant]

Skids is right, cams are synced but the crank looks off by a tooth.

[randy]

I wouldn't rely on the pointer if you suspect a timing problem. The pointer is moveable, too. I would establish true TDC on cylinder #1, then see if it corresponds on the cams. If you get the cams lined up and cyl #1 IS at TDC, then you can reset the pointer to where it should be. That will establish all the marks to their base positions.

[blue giant]

I wouldn't rely on the pointer if you suspect a timing problem. The pointer is moveable, too. I would establish true TDC on cylinder #1, then see if it corresponds on the cams. If you get the cams lined up and cyl #1 IS at TDC, then you can reset the pointer to where it should be. That will establish all the marks to their base positions.

Good point Randy!

(no pun intended)

[SFerinTEXAS]

I just went thru this a few weeks ago after pulling the tensioner to stop a leak. Plunger failed to release properly and ended up with same conditions. When the cam dots were up the timing pointer was at least 20 some-odd degrees off. The obvious symptoms were it wouldnt start normally but would if I twisted the throttle all the way open when cranking but didnt stay running. Lucky didnt bend any valves so I lined the pointer at the T mark and took the cam sprockets loose and rotated the cam dots up and put the sprockets back on .That is the short version, the rest of the details will be obvious as you go.

[randy]

Oh, one more thing, good idea to make sure your advance mechanism is not stuck. The plate should have a spring action when rotated gently by hand counterclockwise. Just grab it with your hand and give it a twist, it should spring back to rest smoothly and firmly.

[SFerinTEXAS]

The plate should have a spring action when rotated gently by hand

The plate bolts solidly with the crankshaft and will not move. Only the advance mech moves.

[randy]

DUH-UH! (ducking for cover) Did I have distributor rotor on my mind?

[tarzan]

I ran a compression test.First with butterflies closed,dohh.
Then with carbs removed.
150,155,155,150,with carbs off
One thing I noticed was when the carbs were on and butterflies closed I was getting 60,100,105,90.
Does the latter set of numbers mean anything?Also added oil to cylinder's one and two after first test because numbers were so low and the numbers were the same after second test with butterflies closed.
That is when I realized I needed to test with butterflies open.
So now I am a little confused about #1 fouling the plug and letting air back draft through that carb.None of the three other cylinders does this.
Can that happen due to the tight tolerance on #1 intake valve,or would that indicate a burnt valve?
I dont have a leak down tester so I cant really test that.
Rick

[cywelchjr]

I ran a compression test.First with butterflies closed,dohh.
Then with carbs removed.
150,155,155,150,with carbs off
One thing I noticed was when the carbs were on and butterflies closed I was getting 60,100,105,90.
Does the latter set of numbers mean anything?Also added oil to cylinder's one and two after first test because numbers were so low and the numbers were the same after second test with butterflies closed.
That is when I realized I needed to test with butterflies open.
So now I am a little confused about #1 fouling the plug and letting air back draft through that carb.None of the three other cylinders does this.
Can that happen due to the tight tolerance on #1 intake valve,or would that indicate a burnt valve?
I dont have a leak down tester so I cant really test that.
Rick

Those numbers with the carbs on and butterflies closed would lead me to think syncronization. Assuming steady cranking speed during the test, this would lead me to believe that the carbs are restricting air flow at different rates.

[DGXSER]

Those 150 numbers are right where I am on compression (at WOT that is). Tends to make me think your indicator is just off. I'd remove plug #1, put a dowel or something in the cylinder and use that as a gage for when you reach TDC (thanks Lorax ). Then check where your pointer is pointing.

[tarzan]

The indicator is right,I checked TDC today when I did the compression check.

cywelchjr got me thinking with his query

Those numbers with the carbs on and butterflies closed would lead me to think syncronization. Assuming steady cranking speed during the test, this would lead me to believe that the carbs are restricting air flow at different rates.

So I put it back together and fired it up (I moved the plugs around first)
Then synced the carbs.They were off a little.#1 was worst.I'm having trouble now with the sync changing as it idles.
I took it for a couple mile ride.Its starting to miss at idle again.But now #2 is cold and #1 is hot.
So I'll get a new plug,resync and try again.
I have a hunch the carbs arent quite right yet.(brain surgeon eh?)lol

[Dragon Tamer]

Tarzan,
It would sound to me that with those compression numbers that your valves are probably Ok but just slightly out of time. Adjust those cam sprockets carefully and try it again. Sometimes it only takes a very little timing to make a large effect. Not to say that there might not be some small valve damage but the chances at this point are small. I am thinking that Skids may be correct and the chain has moved at least one tooth. Have you checked the travel on the tensioner?