Meaning of the markings visible throught the right hand side viewport?

[p6x]

1 hour ago, LowRyter said:

the simple mnemonic joke... D = dis side  /  S = s'not dis side   (works for me).

Here's another hint.  Once you've found TDC, take a marker to alternator rotor.   Mark "D" at midnight, and the same mark will be for  "S" at 3 pm.   If the feeler gauge doesn't go in, it means your on exhaust stroke, you're 360 degrees off and you're at noon, rather than midnight. 

This is much easier than taking a flashlight and looking for those little letters each time.

I do not have a "D" for destro if related to cilindro destro, lato destro.

In any case, the marking on my fly wheel does not correspond to the PMH or TDC.

I just check the play to confirm my rockers are free, with the top of the piston visible. That should do it.

[Tomchri]

Said m times before. See your ex valve goes down and up, intake valve down and up. Piston at tdc. Straw useful just before tdc. Clockwise only. 
Cheers Tom.

[GuzziMoto]

1 hour ago, p6x said:

I did the left hand side.

At PMH (TDC), the "S" marking does not appear in the viewport. But the piston is clearly visible through the spark plug port, since it is tangential.

You are correct, moving the engine by rotating the wheel is not easy because there is very little movement required to jump the TDC when you are in sixth gear. It is a seek and trial to get it right.

And I can confirm I do not have a "D" that I can find on the side of the flywheel. Luigi went for a bathroom break and when he came back, the engine had moved to the next station.

 

I think you may have it backwards. When you are in sixth gear it takes much more movement of the rear tire for a given amount of piston movement. The lower the gear you are in the less the rear tire moves for a given amount of piston movement. So putting it in the highest gear means that it takes more movement of the rear tire for a given amount of piston movement.

Trying to do it in first or second gear is harder, it is harder to move the rear tire and every movement of the rear tire results in more movement of the piston. It is easier when it is in top gear.

Also, you don't need to be exactly at TDC, as Pete said. You only need to be in the ballpark. If you are near TDC at the right point in the four strokes, meaning you are near TDC at combustion, when both intake and exhaust valves are closed, close is good enough. You just need both cam lobes to be on their respective base circles so there is clearance. No clearance and you are probably at overlap instead of combustion.

[LowRyter]

You might use the alternator, a deep 24mm socket, remove 4 bolts holding the cover, twist the socket clockwise.  Once you find TDC (any method you prefer), then mark the rotor at 12 o'clock.  Then you'll never fumble with a flashlight, straw or dowel ever again.  

 

BTDT.

[audiomick]

5 hours ago, Tomchri said:

Said m times before. See your ex valve goes down and up, intake valve down and up. Piston at tdc. Straw useful just before tdc. Clockwise only. 
Cheers Tom.

Yes, exactly.

Getting the alternator cover off is complicated on mine, as I have the crossover between the headers which sits in front of the alternator cover. Nevertheless, I prefer a spanner (socket) on the alternator to turn over the motor.

Whatever the method is to turn over the motor, the straw is very useful. Actually, I prefer to use a piece of heat shrink tube. Because: it happens to be lying around in easy reach of the work bench, it is soft enough to not damage anything inside the motor, and tough enough to not get chewed up if it does get jammed in there a bit.

The "straw" is useful because it means I can be watching the valves whilst turning the motor with one hand and feeling what the "straw" is doing with the other.

I turn the motor until it gets to TDC. Generally it kind of pops past the precise point. I've always assumed that this has to do with what the valve springs on the other piston are doing. So, I go back a bit and approach the point again. I have observed where I was at with the spanner on the alternator and what the straw was doing, and can find the TDC on the second approach very precisely.

 

By the way, the reason for always approaching the TDC in the correct direction of motor rotation is to ensure that all the slop in the cam chain and so on is being taken up be the tensioner in the way the manufacturer intended, i.e. any backlash or whatever is there where it will be at when the motor is really running. Seems logical to me...

[p6x]

5 hours ago, Tomchri said:

Said m times before. See your ex valve goes down and up, intake valve down and up. Piston at tdc. Straw useful just before tdc. Clockwise only. 
Cheers Tom.

Why would spin direction make any difference? just curious. TDC is TDC coming from either way?

 

[p6x]

4 hours ago, GuzziMoto said:

I think you may have it backwards. When you are in sixth gear it takes much more movement of the rear tire for a given amount of piston movement. The lower the gear you are in the less the rear tire moves for a given amount of piston movement. So putting it in the highest gear means that it takes more movement of the rear tire for a given amount of piston movement.

Trying to do it in first or second gear is harder, it is harder to move the rear tire and every movement of the rear tire results in more movement of the piston. It is easier when it is in top gear.

Also, you don't need to be exactly at TDC, as Pete said. You only need to be in the ballpark. If you are near TDC at the right point in the four strokes, meaning you are near TDC at combustion, when both intake and exhaust valves are closed, close is good enough. You just need both cam lobes to be on their respective base circles so there is clearance. No clearance and you are probably at overlap instead of combustion.

I agree on more spin needed. Which makes it easier to pin point TDC, even if it requires more spinning.

Agreed also on being around the mark.

I used both rockers play, and piston TDC both sides. Adjust the gap, did one complete cycle and verified.

[audiomick]

28 minutes ago, p6x said:

Why would spin direction make any difference? just curious. TDC is TDC coming from either way?

 

You apparently didn't read my last post, immediatly before yours with that question, all the way to the end. Here it is again...

40 minutes ago, audiomick said:

By the way, the reason for always approaching the TDC in the correct direction of motor rotation is to ensure that all the slop in the cam chain and so on is being taken up be the tensioner in the way the manufacturer intended, i.e. any backlash or whatever is there where it will be at when the motor is really running. Seems logical to me...

 

[GuzziMoto]

Spinning the motor backwards is not a major issue in my opinion, especially since we are no longer setting timing or doing anything where the slack in the timing system would matter. But I still recommend you always rotate the motor the direction it is made to rotate in. I don't believe rotating the motor the wrong direction will instantly do any harm. But it is good practice to always rotate an internal combustion engine the direction it was made to rotate in. The cams were designed to go that direction, the ramps on each side of the lobes were machined to go that direction. The tensioner in the timing chain was designed to go that direction.

That said, do what you want. I do know that for setting valve clearances the exact position of the crank doesn't matter. As long as the cam tappet is near enough on the other side of the cam from the lobe that opens the valve you are good. If it is off by a little bit it will make no difference. Heck, it could probably be off by 90 degrees of crank rotation and it probably won't make a difference (90 degrees of crank rotation is only 45 degrees of cam rotation). I would try to get to TDC at combustion, but as long as you are in the ball park you are fine. No reason to stress about being exact. Your valve adjustment won't be any better because you were precise about being at TDC.

[p6x]

On 8/29/2023 at 7:06 PM, audiomick said:

You apparently didn't read my last post, immediatly before yours with that question, all the way to the end. Here it is again...

 

 

On 8/30/2023 at 10:53 AM, GuzziMoto said:

Spinning the motor backwards is not a major issue in my opinion, especially since we are no longer setting timing or doing anything where the slack in the timing system would matter. But I still recommend you always rotate the motor the direction it is made to rotate in. I don't believe rotating the motor the wrong direction will instantly do any harm. But it is good practice to always rotate an internal combustion engine the direction it was made to rotate in. The cams were designed to go that direction, the ramps on each side of the lobes were machined to go that direction. The tensioner in the timing chain was designed to go that direction.

That said, do what you want. I do know that for setting valve clearances the exact position of the crank doesn't matter. As long as the cam tappet is near enough on the other side of the cam from the lobe that opens the valve you are good. If it is off by a little bit it will make no difference. Heck, it could probably be off by 90 degrees of crank rotation and it probably won't make a difference (90 degrees of crank rotation is only 45 degrees of cam rotation). I would try to get to TDC at combustion, but as long as you are in the ball park you are fine. No reason to stress about being exact. Your valve adjustment won't be any better because you were precise about being at TDC.

I did some more investigation into the reason why one may want to spin the engine in the correct direction.

Something that we have not discussed here yet?

During our four cycles, the piston goes up twice, but there is only one TDC.

The true TDC happens between the compression and ignition phase. The other piston up is apparently called "the overlap"; between exhaust and admission. This is because the exhaust and admission valves are supposed to have a very small overlap when the exhaust valve is closing while the admission valve begins to open.

It makes sense to turn your engine in its natural cycles direction, to differentiate TDC from "Overlap", as if you are in the "overlap" position, the piston will still be at the top, but either exhaust or admission valves could be actuated.

 

[pete roper]

TDC=Top Dead Centre. It occurs twice in the 720 degree cycle of the motor. Both times the piston is at the top of its stroke it is at TDC but on only one occasion are the tappets on the base circles of the cams and that is when you adjust the clearance.

[GuzziMoto]

What Pete said.

It is true that you can't properly set valve clearance if you are at the wrong TDC. But if you spin the engine in either direction you will see both TDC's, the one that has both valves open followed by the one that has both valves closed, followed again by the one that has both valves open. It just goes on.

As to spinning the engine backwards, in my opinion it is not critical with the V11 engine but just as a matter of practice I always spin the engine the direction it was built to spin. Spinning it backwards will not damage it. It will not affect setting valve clearances. It isn't going to make your wife leave you. But I would still suggest as a matter of proper practice spinning the engine in the direction it was made to spin. If we were setting cam timing or ignition timing it might actually make a difference. We are not, so it doesn't. But it is still the right thing to do.

[p6x]

Right; I think we are all in agreement.

We agree there are two TDCs, only one should be used to adjust the valves' gap.

Spinning the engine either direction achieves the same, while it is preferred to turn it in its normal working direction.

[audiomick]

That's how I see it.

[MartyNZ]

On 8/30/2023 at 12:13 AM, GuzziMoto said:

 Using the rear tire also makes it easy to make sure you turn the motor the right direction (you don't want to turn the motor backwards for any of this). 

I always make sure that I turn the engine forwards before valve adjustment too.

We know the thrust washer on the forward end of the camshaft can wear on the fwd face, so the shaft is loaded aft when running. I assume this is because the cam lobes run off-center of the cam followers to rotate the followers.

Turning the engine backwards may let the camshaft move forward and change the valve clearance. 

Also the oil pump will deprime itself so oil pressure will be slower to rise on the next start.