ANOTHER timing mark question...

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Lmo
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ANOTHER timing mark question...

Post by Lmo » Sun Aug 14, 2016 1:01 pm

NO PROPER TIMING MARKS .... SERIOUSLY ?!?

I mentioned this in my Harmonizer thread. The timing "scratches" on my flywheel are not very convincing, and it's hard to tell what to line-up because the mark isn't "straight"; they look like they might have been made with a screwdriver.. .. .

I can find TDC by rotating the crank with the plugs out. But the ignition timing is a bit more problematic; one of the two scratches has white paint dabbed on it, would this (more than likely) be the ignition timing mark (so it was more visible under a timing light) ? I guess by Sherlockian logic, if the painted scratch is NOT at TDC then it must be the ignition timing mark.

Thoughts
Lew Morris
Dnepr w/ '06 Ural Drive Train
C5 Power Arc
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Drilled slides/
.030" shims

1973 BMW R75/5 (original owner)
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Re: ANOTHER timing mark question...

Post by on2wheels52 » Sun Aug 14, 2016 2:41 pm

I punched my own TDC after finding the spot (it was close to original). My 30 year old Snap-On timing light has an advance dial so you can see what degree the engine is set, even total advance.
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Re: ANOTHER timing mark question...

Post by Albuquralque » Sun Aug 14, 2016 3:26 pm

When you put the engine at TDC, is there a mark in the middle of the timing window?

When rotating the engine around to TDC, the timing mark will come into the window just before the TDC mark.

Hope this helps
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Lmo
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Re: ANOTHER timing mark question...

Post by Lmo » Sun Aug 14, 2016 7:45 pm

Yes, I've got two crudely scratched lines.

As the crank rotates with the kick starter pedal, the first mark to appear has been dabbed with white paint. With the ignition on (no Kill switch), the LED on the Type V puck is ON ( I thought it should be OFF) per http://myural.com/TYPEIVIgnitionTiming.htm

As the engine is rotated to the second mark (both are visible through the crankcase hole at the same time) the light goes OFF ( so this would be a "retarded" condition? ). I realigned the paint-marked line, pulled the front cover, and rotated the ignition module CCW until the the LED was ON, and then slowly rotated it back CW until the LED just went OFF. Since I didn't want to start the engine before doing the valves I haven't had a chance to see if the change even runs.

But the engine seemed to be running well, I pushed it to 65 mph yesterday afternoon for a few minutes. The left plug was a bit sooty around the electrode insulator but the electrode itself was a nice gray. The right plug looks normal. Idle seems a tad high (both idle jets are around 2+ turns out) and is slow to return to idle (which is why I'm trying to sort out the timing; carb sync will follow that.)

I pulled the valve covers (for the first time) this afternoon and found both intake valves set right on .004" and both exhaust valves at .008". I reset the left bank to .002" and .004" respectively, but have to pull the chair to get the right valve cover off (remember... '63 Dnepr chassis, '06 Ural engine). I could get a feeler gauge on the right side tappets and they were .004" and .007" respectively. ( I just couldn't get a wrench on them to adjust them). We're having company over this evening so I had to abort early.

So there are a few variables involved here. Order of business; get the the valve gaps squared away, get the ignition timing set, reset carburetor idle, and finally sync.... nothing like changing a bunch of stuff at the same time, huh?
Lew Morris
Dnepr w/ '06 Ural Drive Train
C5 Power Arc
125/42 jets
Drilled slides/
.030" shims

1973 BMW R75/5 (original owner)
1947 HD FL (long gone, forever regretful)

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Re: ANOTHER timing mark question...

Post by Albuquralque » Sun Aug 14, 2016 8:06 pm

By your description then, the painted mark is the timing mark and it sounds like you adjusted your timing correctly.
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Re: ANOTHER timing mark question...

Post by Snakeoil » Mon Aug 15, 2016 10:03 pm

If you want to be sure that you scratches are accurate, you could put a degree wheel on the crank.

If you end up remarking your crank, use a low stress (radiused) punch and not a sharp pointed one.
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Rob
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Re: ANOTHER timing mark question...

Post by Lmo » Tue Aug 16, 2016 10:34 am

will the pointy one split the flywheel?
Lew Morris
Dnepr w/ '06 Ural Drive Train
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Drilled slides/
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Re: ANOTHER timing mark question...

Post by INSUBORDINATOR » Tue Aug 16, 2016 11:03 am

Even though my timing plug is on the left side & easy to see - I don't use the TDC mark to set my valves. I use the TWIRL METHOD outlined by F2 Motors. it relies on the actual conditions of the individual cam. It is a very simple & foolproof method. & has worked for me for decades.
Only mention this as a reminder that this is possible. Stories have surfaced of timing marks being wrong sometimes.
It can be found on Google & searching this forum.
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Re: ANOTHER timing mark question...

Post by rougaroo » Tue Aug 16, 2016 11:41 am

Simplistic explanation: take out the sparkplugs to make the engine easier to turn over. Key off, use the kick start to slowly turn the engine over while you look through the timing hole. The first mark to come around is the timing mark; the second is the TDC mark. Think about the geometry for a sec - spark that comes ahead of the TDC mark is "advanced", spark that comes after the TDC mark is "retarded". Our airheads need advanced timing, not retarded (some water-cooled engines use retarded timing - no jokes here).

Don't trust your timing light to tell you whether your mark is right. Trust the mark to tell you the timing is right (at least initially, until you've ruled out other things). Your description of the LED tells me that the timing was ok. The procedure with that ignition and the PowerArc is to sit the flywheel at the timing mark, turn the key to ON, turn the ignition module until the LED just comes on, then tighten down the module set screw. You're timed right.

If you really suspect your TDC mark is off, or you just want to confirm it is in the right place, people have already mentioned a number of ways to find out. The F2 swirl method is good, but it depends on the valve tappets being at least somewhat close to where they should be. Another way is to use a soda straw or a thin bamboo skewer and insert it into the spark plug hole up against the top of the piston. Rotate the engine and feel the straw/stick. You will know when the piston reaches the top, as it starts going back down again. If you are a real purist you can put the bike up on the center stand, leave it in gear, and use the pusher to move the piston forward and backward slightly. Once you are satisfied, look at the valves on that side. If the valves are closed, then it is TDC on the opposite cylinder. If the valves are open, then it is TDC on that cylinder.

Because of crud on the flywheel and my aging eyes, I painted the whole area of the timing mark and TDC mark with white paint, then marked the marks with black paint. The black-line-against-white-background jumps right out with a timing light.

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Re: ANOTHER timing mark question...

Post by Snakeoil » Tue Aug 16, 2016 11:45 am

Lmo wrote:will the pointy one split the flywheel?
No. But it will create a stress riser and present a risk for crack initiation. Rotating parts should always be marked with low stress stamps. If you look at letter and number stamps used on rotating parts, or the impressions they leave behind, you will see that they have a smooth radius on them at the bottom of the created impressions.
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Rob
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Re: ANOTHER timing mark question...

Post by Lmo » Tue Aug 16, 2016 5:56 pm

Lmo wrote:
will the pointy one split the flywheel?
I was half way kidding when I said that. But in 1981 I did observe a 48" punch press flywheel shear off the crankshaft it was on ... it crushed the concrete floor under it and still had enough rotational energy to take off across the factory floor. It finally came to rest when it hit the concrete building wall about fifty feet away. It was third shift and somehow no one got hurt, but you should have seen the look on the press operator's face. Crap, you should have seen the look on all of our faces. The tool shop manager was attempting to hit more "stroke" out of the old press and turned a new crank for it ... guess "close enough engineering" wasn't good enough in this case.

I've pretty much always "confirmed" the condition of the lifters by 1) pulling the plugs and observing the piston rise, 2) twisting the push rods, and 3) tugging on the lifters to feel any movement.
Lew Morris
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Drilled slides/
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Re: ANOTHER timing mark question...

Post by Lmo » Tue Aug 16, 2016 6:05 pm

Just remember this... years ago I worked as the fiberglass monkey in a Formula Ford racing shop. Great fun. The lead wrench made a tool out of an old spark plug base (with the insulator knocked out of it) and a piece of 1/4" steel round stock welded into it. He determined how deep to weld the piece into the plug base by rotating the crank until he got his "zero" lift (as measured with a dial micrometer). He'd insert the tool, without the crush washer, into whatever cylinder was supposed to be TDC'd and gently rotate the crank until it bumped the end of the tool ... instant, no guess. Might work for the Ural too.
Lew Morris
Dnepr w/ '06 Ural Drive Train
C5 Power Arc
125/42 jets
Drilled slides/
.030" shims

1973 BMW R75/5 (original owner)
1947 HD FL (long gone, forever regretful)

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Re: ANOTHER timing mark question...

Post by Snakeoil » Tue Aug 16, 2016 7:21 pm

That method is close but not perfect. I suspect that your mechanic rotated the engine both clockwise and then counter clockwise and marked both positions where it stopped. He then split the distance between the two marks and that was TDC.

Engines with the plug mounted in the center of the chamber are best suited for this method. Those with the plug off to the side need a robust stop because a thin one will flex since the piston is putting somewhat of a sideload on it.

That punch press story is a good one. There were a few like that at the GE plant in Schenectady. A generator rotor burst while in the spin pit. It killed the engineers that were at the pit controls and I was told a piece of the rotor went up thru the mezzanine, thru a meeting room table, thru the roof and landed out in the parking lot.

When spinning things fail, they fail in a big way.
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Rob
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Re: ANOTHER timing mark question...

Post by Scott C » Fri Aug 19, 2016 9:50 pm

Just put TDC and timing marks on my new flywheel yesterday using a piston stop and compass to find TDC.

http://sovietsteeds.com/forums/viewtopi ... =5&t=34090
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Re: ANOTHER timing mark question...

Post by JPanyon » Fri Aug 19, 2016 11:30 pm

Sorry that I'm late to this chat, but WWID about finding TDC...? Take out the plugs to make engine easy to spin, get the pusher wheel off the ground, put tranny into 4 th gear. Use a hand held drinking straw inserted into left plug hole, rotate engine with kick start lever, and when you feel straw moving upwards use the rear wheel to finish moving the left piston to max height. Then check the observer port and see if there is a line scribed. If not, you need to rotate the crankshaft another full turn and get the left piston back to top, again. Now there should be a scribed line in the middle of the observer port. If you rock the engine backwards using the rear wheel, the timing mark should appear before the top dead center mark disappears.

This lets you roughly check the correctness of the TDC mark on the flywheel, and the timing mark. When the timing has been set using the manufacturers directions, you should be fairly close to "good". Then if you want to use a timing light, use it to verify that at idle your system is firing when the timing mark is roughly in the middle of the window, or to verify that the timing mark is correctly positioned on the flywheel relative to Top Dead Center marking. You can use the timing adjustment on the ignition system to fine tune the setting. Older slower timing lights can be confused by a multiple spark system. Newer units are fast enough to catch the first pulse reliably and ignore the rest, as they really don't affect timing but just ensure complete ignition.

Enjoy...
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