Tonti Timing after Timing Chain Transplant

[ozarquebus]

OK, here we go again. I am trying to set ignition timing on the G5 after replacing the timing chain. I am reading three different manuals, This Old Tractor and reading every post here and it won't fire. Every description has a different point of reference and technique. It was running rather good before I replaced timing chain. It is hard enough just figuring out what is right and left.
 On the compression stroke for the right cylinder, from the orientation when sitting on bike, using thumb over spark plug hole method, I have aligned with the "D" on the flywheel when viewed through the timing port. The lower set of points with the black wire in the distributor are open and set to the correct gap. There is gas in the tank.
 Is this correct so far or is my cam out of alignment with the crank, cuz it seems like the lower points are for the left cylinder.?

[guzzisteve]

Bottom set is L/H and top set is R/H according to the V1000 SP/G5 manual I got.

[delrod]

John I have a copy of Guzziology in Pittsburg if you have a need

[ozarquebus]

I should have the knowledge to get it done at this point, thankyou delrod.
 Since the left points are opening when the right piston is at TDC it must be 180 out.
Looks like I need to get a degree wheel and reinstall the timing chain. At least that will be easier since I just did it and I should have a thorough understanding when done.
  I was careful not to turn the cam independent of the crank, but somehow they must have gotten disoriented. I guess that is why they make the cam holding fixture that I did not use.

[wymple]

Why can't you just take the chain off, rotate the cam 1 full turn & reinstall? Either that or rotate the crank 1/2 turn instead.

Sorry, I should have said 1/2 turn on either one. Brain fart.

[ozarquebus]

I didnt remove the distributor.

[Kiwi_Roy]

As the piston goes to TDC on the exhaust stroke the exhaust valve will be open, then it reaches TDC the exhaust valve will be closing but the inlet valve will be opening.
At TDC both valves will be open about the same amount Exhaust closing Inlet opening, get the chain out by 1 tooth and it will be quite obvious.
From TDC turn the motor 1 complete turn and at the next TDC the points for that cylinder have just opened.

[ozarquebus]

I know why Antietam thinks my distributor is 180 off since I said engine is at TDC on compression opening left points with "D" on flywheel.

Is it correct to say that if sprocket marks are aligned on the timing chain asembly, then the cam to crank relationship must be correct?

Even though the crank spins twice for one revolution of the cam, to rotate either cam or crank one revolution independently will only bring you back to same setting.

Since dizzy was not removed and the bike ran ok before, then I must be an idiot and the motor is not not really be at TDC compression for the right cylinder

[Rich A]

...and "right" side (D) means relative to when you're sitting on the bike.

Rich A

[bmc5733946]

Straw, bamboo skewer, or chopstick in plug hole, watch intake valve, piston coming up valve closed. Make sure you are rotating engine in correct direction by using starter button and watching crank or flywheel rotate. Then rotate by hand using wrench on crank bolt or using rear wheel while in gear.. For me I have never been able to get this correct using thumb over spark plug hole. Too many variables. YMMV.

Brian

[guzzisteve]

Straw, bamboo skewer, or chopstick in plug hole, watch intake valve, piston coming up valve closed, make sure you are rotating engine in correct direction by using starter button and watching crank rotate. For I have never been able to get this correct using thumb over spark plug hole. Too many variables.. YMMV.

Brian

There you have it.  Looking in hole for marks on flywheel, the flywheel comes UP in the hole if you are doing it right. Dizzy is in correctly if the points face towards the rear.

[Chuck in Indiana]

I always set the timing on the left cylinder. S cylinder. "S'not dis side.." Dis side is the distributor side or timing hole. Turn the engine in the direction of normal rotation. (Clockwise, looking from the front.) Watch the S cylinder's intake valve. When it opens and then starts to close, that piston is coming up on TDC ready to fire. At TDC, the initial timing mark on the flywheel should be visible in the porthole. Set that in the center of the porthole, and set the distributors points to fire the left cylinder. That will get you in the ball park, and final timing can be set with a timing light.

[rutgery]

Maybe you remember from replacing the chain if the Left hand (LH) cylinder was in top dead center (TDC) when the chain sprocket marks lined up? If not, I'd do the following;

To check if the camshaft is in the correct position of the crank, rotate crank until the D mark is visible on the flywheel (center of looking hole).
The Right hand (RH) piston is now in TDC.
Remove the valve cover of the RH cylinder.
Check if the valves are both partially opened. They should be about equally opened with a correctly installed cam.

IF this is NOT the case, remove the sprocket&chain with the LH cylinder in TDC, rotate the crank until marks line up and reinstall the chain.


If this is the case, (valves both equally partially opened) Remove the distributor cover.
Reset the point gap to make sure.
Rotate the crank until the static timing mark for the D cylinder (line above TDC mark) is in the center of the looking hole.
Loosen the two lower distributor mount bolts.
Rotate the distributor so the RH point gap JUST opens, not to the correct clearance. This clearance should only be achieved if the point is on the top of the lobe.

Using these settings you'll know for certain that the point is opening at least fairly correctly and the bike should run. You can tune the ignition timing further by using a timing light but that won't change the running dramatically if the previous steps are done correctly.

Good luck with your G5!

PS: you haven't changed flywheel right? Different flywheels can have very different marks on them, not representative of your bike and distributor..

[80CX100]

     When I did the timing chain on my CX100 and tried to set my points the first time, I watched the valves, chopsticks, TDC etc.

     I was having no success with the static timing and was so sure I screwed up, I reopened the timing chest to check my work with the chain and gears, it was fine.

     KiwiRoy gave me some sound advice with the final fix. 

     I removed the distributor cover as well as the valve covers so I could see both the valves and the points working together.

     Didn't take long watching the valves and points opening and closing, to get me back on track setting the timing on the right TDC stroke,lol.

     Take a good look at it again before you reopen the timing chest. fwiw ymmv

     Good luck

     Kelly

[John A]

The cylinders are numbered front to back , not left to right. The forward cylinder is #1.
#2 cylinder is where you set timing.

[Huzo]

I don’t know what a G5 is, but does it look like this ?

[ozarquebus]

Yes Huzo, exactly

[Kiwi_Roy]

Aren't the timing marks on the flywheel?
Who's to say the flywheel was put back in the right place, there are 6 possible positions.

[wymple]

"Even though the crank spins twice for one revolution of the cam, to rotate either cam or crank one revolution independently will only bring you back to same setting."

Spin the crank 1/2 turn.

[Huzo]

Yes Huzo, exactly

Can you identify that your marks are the same as these ?

[Huzo]

"Even though the crank spins twice for one revolution of the cam, to rotate either cam or crank one revolution independently will only bring you back to same setting."

Spin the crank 1/2 turn.

Unless I’m misunderstanding..
The crank needs to be rotated one FULL turn if you wish to accomplish your goal. One crank revolution is half a combustion cycle.
However.
If your marks are the same as in my shot and the flywheel has not been disturbed, you should be ok.
Do this..
Bring your number 1 cylinder (left gearshift side) to TDC on the ignition stroke, use the straw method, you will get very close if you perservere.
Verify this by noting lash on both tappets for left cylinder.
In this condition the points should have JUST opened for the left cylinder, you are at full retard remember.
If your timing marks are as per photo ?
I cannot tell you more.
Check that you are rotating the crank in correct direction by pulling the plugs and watching the rotation of the rear wheel while turning the crank in gear.
Make sure you have the left coil and right coil correctly wired and the plug leads are not crossed.
Ensure that you have some clearance on the tappets at TDC.

[wymple]

"The crank needs to be rotated one FULL turn if you wish to accomplish your goal. One crank revolution is half a combustion cycle."

Only if the cam is connected. A piston on one full turn still goes from TDC to TDC where it was to begin with. Whether it's on the power stroke or not depends on the cam.

[jacksonracingcomau]

Late to the party here but answers are getting miles from the question.

OP changed the chain without touching the breaker housing or points themselves.
Obviosly the relationship between camshaft and ignition remained as it was.
So the variation in ignition timing could only be minute, the wear on the chain.
The bike should start and run, use strobe to verify ignition  timing as per routine service.

Or something has changed
1 Cam timing, verify dots line up
2 complete coincidence, something else happened, wire fallen off etc

I tend to think it’s 2.
There is a 3 , that valve timing WAS one tooth out before, ignition timed to suit , ignition would be miles out when valve timing corrected. But sweet running before suggests this is not the case.

[Huzo]

"The crank needs to be rotated one FULL turn if you wish to accomplish your goal. One crank revolution is half a combustion cycle."

Only if the cam is connected. A piston on one full turn still goes from TDC to TDC where it was to begin with. Whether it's on the power stroke or not depends on the cam.

Oh yes.
There is no doubt you are correct, sorry.
My point was that rotating half a revolution is not ok, but my statement was not correct as I presented it.

[Howard R]

The English translation is very simple:
"S" = Starter side, rear or #2 cylinder
"D" = Driveshaft side, front or #1 cylinder

As others have mentioned up thread, make sure you're rotating in the correct direction.  Turn the fastener on the front of the crankshaft with a ratchet set to "tighten," if you're standing on the Driveshaft side you will be pulling up on the wrench, while watching the valves on the cylinder of choice.  Intake valve opens and then closes, you're coming up to TDC on compression stroke.  Look for flywheel marks in the porthole, when the letter comes into view double check with plastic straw or flashlight in spark plug hole for piston position.  Slowly make one more revolution of the crankshaft while watching the flywheel marks in the porthole, to see where the timing mark is in relation to the letter, then continue rotating until your desired timing mark comes back into view.  (This will put you back on compression stroke, verify by watching valves & checking piston position.)  That should get you close enough for timing to get the engine running, fine tune with timing light.

Good luck!

Howard

[ozarquebus]

IT RUNS!!!!! with the musical whir of a new banana damper against a new timing chain equal to a Verdi opera to my ears. I even took the allen wrench out of the rotor bolt before spinning it up.

Nothing was wrong. I did it right. Gas lines were kinked when I raised tank to get at points which prevented starting (what an idiot).
I also made error in finding TDC using the thumb over hole method.

 The points gaps even remained in range and did not require adjustment.

Many thanks to all the responses, even the imperfect ones. They required thinking on my part as well.

Before undertaking this task I had several misconceptions and knowledge gaps about the mysteries of valve timing and ignition timing of the Guzzi Big Block.

Now, I am still no expert but its workings are fairly clear and it only took me 6 months.

 You Wild Guzzi helpers are the best on the planet!

Thank you...Thank you...Thank you.

[Chuck in Indiana]

^^^^^We're always happy to see a satisfied customer.

[wymple]

Guzzis will always run in the end.....

[jacksonracingcomau]

Late to the party here but answers are getting miles from the question.

OP changed the chain without touching the breaker housing or points themselves.
Obviosly the relationship between camshaft and ignition remained as it was.
So the variation in ignition timing could only be minute, the wear on the chain.
The bike should start and run, use strobe to verify ignition  timing as per routine service.

Or something has changed
1 Cam timing, verify dots line up
2 complete coincidence, something else happened, wire fallen off etc

I tend to think it’s 2.
There is a 3 , that valve timing WAS one tooth out before, ignition timed to suit , ignition would be miles out when valve timing corrected. But sweet running before suggests this is not the case.

Did I win the prize ?
Definitely counts as a 2

[Huzo]

Did I win the prize ?
Definitely counts as a 2

Yes mate you win..
Saying it was definitely something else if it wasn’t that, was a stroke of lateral thinking that leaves me astonished.
You have a good grasp of the bleeding obvious..