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Author Topic: how to check your timing!!!  (Read 11770 times)
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jerb
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« on: August 27, 2009, 05:49:15 PM »

thought i would post some pics in whats involved in checking your ignition timing, this is an ohv, but will also work on flathead, but you will have to pull the head to find top dead center, as a piston stop which i use wont work with a flathead!


the tools you need to have, an old inductive timing light, a piston stop, and a small degree wheel, the one i use came from comp cams!


next i take the nut off the crank, and put the degree wheel on and tighten the nut back down, you may have to pull the tinwork to do this!

next using the above piston stop, pull the sparkplug and turn the engine by hand till the piston is almost to the top of the bore, i use a small screwdriver to feel where the piston is, make sure engine is on compression stroke, next install the piston stop and turn engine clockwise till the piston touches the stop, DO NOT USE STARTER FOR THIS!

now using a piece of stiff wire, bolt it down somewhere on the block, doesnt matter where, i used a starter bolt, bend the wire so it points at a number on the degree wheel, in this case, it points to 140 on the degree wheel, write that number down,

now turn the engine counter clockwise till the piston again hits the stop, and write down the number your pointer is pointing at, which in this case is 178,

 now halfway between 140 and 178 is gonna be true top dead center, which is 159, so pull the piston stop out and turn the engine clockwise till the pointer is exactly on 159, this is top dead center!

now we need the pointer to be on 0 on the degree wheel, you can either move the degree wheel, being careful not to turn crankshaft or simply make a new pointer, making a new pointer is much easier, we dont want to move the crankshaft whatsoever or readings will be off, now that you have the pointer at 0 on degree wheel, reinstall the sparkplug, hook up the timing light, start the engine and point the light at the degree wheel, the pointer will show you exactly how many degrees the sparkplug is firing before top dead center on the compression stroke!!



i tried to get a picture of the timing light showing the degrees on the flywheel, not an easy task and finally gave up!!
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Tim Jerby
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« Reply #1 on: August 27, 2009, 06:25:24 PM »

Do you do it the same way for a v-twin?

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jerb
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« Reply #2 on: August 27, 2009, 06:32:04 PM »

not sure, i would imagine if you put the timing light on the same plug wire for the cylinder you used the stop with, it would work,
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« Reply #2 on: August 27, 2009, 06:32:04 PM »

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« Reply #3 on: August 27, 2009, 10:41:47 PM »

hey jerb thanks for the info ive ask afew people how this is done but no one would go into details so thanks bud!!!
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John Hodge
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« Reply #4 on: August 28, 2009, 07:36:16 AM »

 +1
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« Reply #5 on: August 28, 2009, 09:28:54 AM »

i vote this should be sticky in the motor section.
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Mark Laird
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« Reply #6 on: August 28, 2009, 01:21:09 PM »

i 2nd that!!!
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John Hodge
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« Reply #7 on: August 28, 2009, 04:34:44 PM »

Great post......My question is this: I have a V-Twin with an ARC flywheel, once I know how many degrees before TDC the spark plug is firing what do I do with the timing of the ARC flywheel?
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jerb
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« Reply #8 on: August 28, 2009, 06:20:43 PM »

Great post......My question is this: I have a V-Twin with an ARC flywheel, once I know how many degrees before TDC the spark plug is firing what do I do with the timing of the ARC flywheel?
adjust it accordingly, till you feel the engine is running its best, each mark on the hub is 2 degrees,  ive checked and the hub marks are pretty darn accurate, some guys even adjust the timing + or - for different track conditions!
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« Reply #9 on: August 28, 2009, 06:32:03 PM »

Is there a need to use a degree wheel for the timing if one has an ARC flywheel?
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« Reply #10 on: August 28, 2009, 06:37:19 PM »

Is there a need to use a degree wheel for the timing if one has an ARC flywheel?
yes.
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jerb
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« Reply #11 on: August 28, 2009, 06:41:54 PM »

Is there a need to use a degree wheel for the timing if one has an ARC flywheel?
once you find where your timing is set with a timing light and degree wheel, thats the last time you really need to check it, i usually write on the arc flywheel with a felt tip pen, what mark was how many degrees, arc dont list what the timing will be on these engines, and you never really know without checking it!
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Tim Jerby
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« Reply #12 on: August 28, 2009, 08:53:47 PM »

i know i need to time my ohv cause seems some the Coil post are offset and somes anit so right now i run full negative just to be safe. But i know theres some room to adjust
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Mark Laird
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jerb
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« Reply #13 on: August 28, 2009, 10:24:33 PM »

every ohv i have seen thus far had the coil offset from where it is on a flathead, the first ohv i built, i degreed the ARC flywheel in, and at full negative using a stock key, it was around 39 degrees, which is way too much, hence the reason alot of guys breaking the cranks on ohv's, i have yet to see an ohv where the coil wasnt offset, not saying they dont exist, but all the ones i have laying around are offset, something to think about guys!
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Tim Jerby
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« Reply #14 on: March 18, 2010, 01:18:27 AM »

someone please sticky this
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John Hodge
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