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If you are using a test light or meter on the points, the mark moves because each single revolution of the engine changes the points cam lobe that is activating the points. The front lobe is thinner than the rear and the mark moves in the window as a result. Nothing to worry about as long as you are timing on the correct cam lobe for the correct cylinder.
 

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Mark the point cam lobe that you are timing on. Make sure that it is the correct lobe for the cylinder that you are timing, and make sure that cylinder is on compression stroke. Start from scratch and do it all again. I'm confident you'll find your answer.
 

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Are you making sure that the advance mechanism is turned to full advance while you set timing? It sounds like you may have a worn out timer assy. The bushings and/or shaft may be worn to the point that there is too much slop to give consistent settings, or maybe the worm gears are worn. Have you replaced the capacitor? At least twice? (I have seen brand new ones bad from the box.)
 

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Back to basics. In your initial post you say that you are rotating the engine one full turn after setting the timing, and that you find the mark in a different place in the window. What are you using as your reference to determine "one full turn"?
 

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Personally, I've never been able to use the kicker to turn an engine over with that kind of finesse. For timing I lift the rear wheel, put the trans in 3rd gear, and bump the wheel, with the plugs out. This lets you go forward and backward with the engine. You've got to understand that the difference between the mark in the center of the window and on the left side of it is only a couple of degrees. It most certainly isn't enough to keep the engine from running. Seems to me like you've got something else going on there. What coil are you running? Are you sure it's good? What voltage are you getting from your battery to the coil? Are there any loose connections in the electrical system? Is it getting fuel? Etc.
 

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I sort of knock the kicker so it makes only tiny movement on the engine, it’s the way I was shown so stuck with it. I will try jacking the bike and turning the engine with the wheel in gear.

I’m running a fairly standard 12v coil which shows good health. Battery is the same, fuel delivery fine, no loose connections, plugs, ht leads etc all fine.

i understand the timing marks movement in a single instance isn’t a worry, my concern is that it’s moving forward with every revolution effectively untiming the bike. Maybe that’s impossible!
If everything is tight, the only way that would be possible would be for the gears to be wrong somehow. If the sprocket shaft was spinning in the flywheel it wouldn't affect that, the pinion shaft can't spin due to the key, unless it's missing. I can't imagine how that could happen, but I suppose it's possible. Maybe the gear is moving on the bottom of the timer shaft? Something isn't right for sure. Try turning the engine over multiple times, stopping each time at the same timing mark position on the flywheel, and taking pics of the points cam position. Always with the timer fully advanced.
 

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Do you have your timer connected to a cable so that it can be operated from the handlebars, or are you moving it by grabbing it by hand and twisting? You are correct that optimum advance for a particular engine is determined by a lot of factors. Compression ratio, cam specs, fuel, heck even humidity in the air if you want to get that technical about it. (racing is the only good reason to get that finicky though) You said that this is a recent build, so you want to break it in easy. Keeping max advance just a bit back from full will prevent pre-detonation while running a few break in miles. After getting it broken in, you can start advancing the timing a degree or so at a time till it starts to run worse, then bring it back a bit. That is how I usually fine tune mine when I want to get that picky about it.
 

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when ya get to the timing mark, set a drinking straw into the front plug hole, then gently rock the crank foreward & backwards until you get ACTUAL TDC & check if the timing mark is in the correct place, it may not have stock flywheels in it, ya never know, mixing flywheels was a comon thing years ago
when at front TDC by either the straw method or by using a Dial guage with a long reach extension for real accuracy you can tell if you are setting Full advance in the correct position.
OKAY, still having a little trouble. It’s running and that’s almost rad enough, however…

i retard timing about 1/3-1/2 of the way, bike starts east 1/2 kicks and idles nicely, when I advance the timing to ride away however the idle speeds up as it should but gets very rough. If I try to to ride away retarded it backfires and rough, but is smooth to take off when advanced.

am I right in thinking this could be because the timing is a little retarded?
What you have going on is the exact reason that automatic advance units were invented, and that before them there was a cable connected to the timer to advance or retard from the handlebars. Engines locked in at full advance are hard to start with a kicker and don't idle smoothly. Engines locked in where they are easy to start are very sluggish at higher RPM. The harsh idle when the timer is in advanced position is something you'll just have to learn to live with if you don't want to either connect a cable to allow you to advance it as your RPM comes up or install an auto-advance unit.
 

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if you set the timing on the front cylinder compression stroke while AT FULL ADVANCE & then lock it so it will not advance too much all you do is twist the timer clockwise to retard it, the advance /retard unit adds or retracts the timing 35*(degrees) i beleive it is,
but retard is not as critical as full advance,
if you dont lock the advance stop & ride over full advance, ya likely to do damage in the long term,
plus loss of power & bad MPG,
retard it by hand till you get the idle beat you like, it doesnt really matter as the motor isn't under load,
but IF you follow the FACTORY MANUAL it's so easy, DONT over think it, just set as the book says,
1)front cylinder on compression stroke,
2) get the timing mark on the flywheel in the timing hole.
3)narrow lobe on points cam JUST ABOUT TO OPEN points at FULL ADVANCE,
3) tighten it down & ride
it aint rocket science, it's 100+ year old technology
He is running an old manual advance style timer, does not have an advance unit installed. This is making it necessary for him to manually retard to start and then advance to run as he doesn't have a cable to the handlebar controls to allow advancing as the engine accelerates.

when ya get to the timing mark, set a drinking straw into the front plug hole, then gently rock the crank foreward & backwards until you get ACTUAL TDC & check if the timing mark is in the correct place, it may not have stock flywheels in it, ya never know, mixing flywheels was a comon thing years ago
when at front TDC by either the straw method or by using a Dial guage with a long reach extension for real accuracy you can tell if you are setting Full advance in the correct position.
Timing is not set at TDC, the timing mark on the flywheels used for setting the timer is the advance mark, and all timing has to be set to the advance position. What you are saying can be used to check the marks, if one has a degree wheel installed on the crank.
 

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I well know that TDCis not the timing mark, but it can be worked out from TDC then reverse the crank untill it's 35 degrees btdc & that should give you the timing point regardless if hes running a timer, with manual advance & retard, or a stock nose cone type or with a magneto,.. there is a piston height btdc that does the same but cant remember it off hand, someone here will know,
As I said when I mentioned using a degree wheel. BUT...............
The point here is not what you or I know or who knows more, it is to HELP Leodavut understand what he is dealing with on his bike. I wasn't trying to be insulting to you with my reply, I was trying to make sure that he understood what he is dealing with, without being distracted into the weeds by comments that really have no immediate bearing on his problem.
 

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I'm glad you got your timing issue sorted. On to the next headache, LOL. Like rhysmort said, welcome to the world of old bikes. It's a constant struggle, but the payoff is worth it to some folks. :D
 
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