Author Topic: Should intake valve be open or closed to get piston to TDC for valve adjust?  (Read 2116 times)

Online Huzo

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Sorry to double up on Kev’s post.
As I was typing mine, he must have been doing his.

Online Old Jock

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THIS..... and PLEASE, don't use a chopstick or wooden dowel.....

Why not?

Online Huzo

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Why not?
I think they are referring to the fact that although unlikely, if you try hard enough, you could snap the end off the stick and drop it in the cylinder.
Because it goes in on an angle to the piston movement, the rising piston can wedge the dowell in the plug hole if you are ham fisted enough and you are wearing your butcher’s apron…. :rolleyes:
« Last Edit: May 27, 2022, 05:32:55 PM by Huzo »

Online Huzo

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It probably makes no difference now, but if you replaced the words “to get” and insert the word “when” in your thread title, it will more accurately express what you are asking..

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Online Cam3512

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Why not?

Because when it breaks off and gets munched between the piston and cylinder, then you have a piece of wood down there.  Then what?
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Online Huzo

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Because when it breaks off and gets munched between the piston and cylinder, then you have a piece of wood down there.  Then what?
Pour some fuel in there and light a match.
That’ll burn it out.
Or stick an Oxy torch in the pug hole and set fire to it….. :thumb:

Online Cam3512

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Pour some fuel in there and light a match.
That’ll burn it out.
Or stick an Oxy torch in the pug hole and set fire to it….. :thumb:

Sure Huzo, that’s the ticket!  But make sure you top off the tank first…
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Online Huzo

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Sure Huzo, that’s the ticket!  But make sure you top off the tank first…
Hell yeah..!
Safety first… :thumb:

Offline Bulldog9

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Why not?

Because this is an Italian bike John, not Japanese........... :evil:

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Offline tris

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All of the above is good stuff but I'd add these couple of points

If put something down the plug hole do so with great caution⚠️
If it snaps off or jams potentially you're into taking the head off to fix

Personally,  set it up the same and with a torch look for the piston down the plug hole

Secondly as an amateur who does this once a year I double check my work.

Pull the  engine over a couple of times and start from scratch

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Offline redrider90

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All of the above is good stuff but I'd add these couple of points

If put something down the plug hole do so with great caution⚠️
If it snaps off or jams potentially you're into taking the head off to fix

Personally,  set it up the same and with a torch look for the piston down the plug hole

Secondly as an amateur who does this once a year I double check my work.

Pull the  engine over a couple of times and start from scratch




I wait to put a long Phillips head screwdriver in just as it approaches TDC that way I ensure it doesn't get jammed. I can rock it back and forth to make sure it is TDC. I bump the check it when done as one time I used the non compression TDC and the valve lash was way loose if I remember correctly. I started the engine and it was making a racket way too loose.
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Online Old Jock

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I think they are referring to the fact that although unlikely, if you try hard enough, you could snap the end off the stick and drop it in the cylinder.
Because it goes in on an angle to the piston movement, the rising piston can wedge the dowell in the plug hole if you are ham fisted enough and you are wearing your butcher’s apron…. :rolleyes:

Thanks Peter, it was a genuine question as I've been using a chopstick or a thin wooden skewer for as long as I can remember to determine approx TDC and never had an issue. It's possible that if you have sausage fingers and no finesse that you could jam it or snap it, as you said you'd have to really make an effort. No offense intended but ff that's the case should you really be working on it in the first place.

Because this is an Italian bike John, not Japanese........... :evil:

That's funny Steve, perhaps I should try using some dry spaghetti in future

John

Offline 1down5up

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I cant figure out why people keep putting wood/straws/screwdrivers etc down the sparkplug hole......

They stuck a mark on the flywheel and a viewing window there for a reason......

Plug out, finger over the plug hole, when you turn the wheel/crankshaft if the compression blows your finger off the plug hole its on the compression stroke..... keep turning until your TDC line on the flywheel is on the mark..... check valve lash/clearance.... repeat for the other side.

maybe if you have lightened your flywheel you have lost your timing marks, but they are easy enough to put back on.


Online Huzo

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I cant figure out why people keep putting wood/straws/screwdrivers etc down the sparkplug hole......

They stuck a mark on the flywheel and a viewing window there for a reason......

Plug out, finger over the plug hole, when you turn the wheel/crankshaft if the compression blows your finger off the plug hole its on the compression stroke..... keep turning until your TDC line on the flywheel is on the mark..... check valve lash/clearance.... repeat for the other side.

maybe if you have lightened your flywheel you have lost your timing marks, but they are easy enough to put back on.
We all understand that what you suggest is correct.
However..
These things cannot be universally held to be true. I advocate checking once to see if the mark is correct, then trust it from there on.
But I would not assume it has been correctly done, just because it’s there.

Online Kev m

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I cant figure out why people keep putting wood/straws/screwdrivers etc down the sparkplug hole......

They stuck a mark on the flywheel and a viewing window there for a reason......

Plug out, finger over the plug hole, when you turn the wheel/crankshaft if the compression blows your finger off the plug hole its on the compression stroke..... keep turning until your TDC line on the flywheel is on the mark..... check valve lash/clearance.... repeat for the other side.

maybe if you have lightened your flywheel you have lost your timing marks, but they are easy enough to put back on.

No THEY DIDN'T on the modern Small Blocks like the OP has.

As for finger over the hole, I never liked that method personally as I'm already turning the crankshaft nut or rear wheel and watching the valves. I'm not a monkey though there are certain resemblances.  :boozing:
« Last Edit: May 28, 2022, 06:52:15 AM by Kev m »
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Offline Bulldog9

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Thanks Peter, it was a genuine question as I've been using a chopstick or a thin wooden skewer for as long as I can remember to determine approx TDC and never had an issue. It's possible that if you have sausage fingers and no finesse that you could jam it or snap it, as you said you'd have to really make an effort. No offense intended but ff that's the case should you really be working on it in the first place.

That's funny Steve, perhaps I should try using some dry spaghetti in future

John

I too used a wooden dowel for 30 years without issue to check TSC on more cars and motorcycles that I can count.

However the first time I used it on my V7 for the 600 mile valve adjust and head retorque, I wasn't prepared for how quickly the cylinder would pop up. Because of the depth of the threads for the spark plug and the angle I snapped a 1-in piece off inside the cylinder. Lesson learned. I should have waited and continue to rotate the motor a little bit more to bring the Piston up before dropping in the dowel.

I had used it without incident on every other car and motorcycle to include five Moto Guzzi's, but the first time on the V7 was not fun.

I now use a 3/8" long extension. It is thick enough to slide easily through the threaded plug hole but stays straight and slides easily upward when the Piston comes up regardless of the angle. I also bring the Piston up about 3/4 of the way before I drop it in. Lesson learned.



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Offline sstone14

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Oh, ok mate.
“Lash” is the term most thrown around in the ‘States, over here we call it “clearance”.
It is the term given to the amount that the end of the rocker arm (under the tappets cover), clears the end of the valve stem.
In the Norge, it is 0.004” for the inlet (rear valve) and 0.006” for the exhaust valve (front valve).
When you are at TDC on the correct stroke, you will feel a very tiny ability to move the rocker up and down. It’s very little but you CAN feel it.
That is where you insert the feeler gauge.
Be careful not to confuse inches with mm when doing your reading.

I could have been a lot more detailed in my description of the top dead centre thing, but thought you’d appreciate brevity.
No one here is out to belittle or patronise you.
We all want the best for each other, you are doing the right thing asking many questions… Keep it up and enjoy.

For sure, thank you! And I totally did not feel that you were belittling me. I appreciate all the feedback, and everyone taking the time to write out responses and help out, to any and all degrees. I'll check back and let you know how it goes once I'm able to get around to it!
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Online chuck peterson

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Just don’t use the long straight ones…they might break in the cylinder and then what will you do?
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