Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Husqvarna => Topic started by: eriksat1 on February 08, 2014, 11:35:59 am
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I saw on some video's that the timing advances from low idle to high on some saws that have the rpm limiting coil, and that the non limiting coil has a static timing through all rpm range. Does a oem limiting coil on a 372xp advance timing? Maybe that is why it is hard to hear the 4 stroking when setting high rpm with a limiting coil? I read the non limiting coil 372xp timing was about 23 BTDC
Anyone play around with ignition timing? I realize the only way to change it is modify the crankshaft key. I'm not going to mess around with that. But I am planning on putting on a non limiting coil and now I am curious.
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I no nothing about the timing of coils. But I had no problems hearing the 4 stroking of either saw using unlimited and limited coils when I tune them both.
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Tuning out of wood is very hard to hear with limiting coil. Now my old 350 with unlimited coil is easy to hear like night and day.
Here is the video I was talking about.
http://www.youtube.com/watch?v=SDrmLhi4isA&list=FLXua3ha1X74GEi89wHhWYPw&index=1
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Not for me. I had no problem hearing 4 stroking on unlimited coils on the 365 372 and the dolmar 7900. Tuning out of the wood to 4 stroking and to where it cleaned up in the cut. ;)
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video is Mitch, mweba his username here.
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Cool, nice video. I am going to do a before and after check of timing on mine since I am putting on a after market non limiting coil.
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It can be hard to hear the difference in a four stroke sound and when it hits limiter.
Usually it is same sound in different tones.
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If guys are tuning for max rpm and hitting the limiter they are not near 4 stroking IMO. They need to get away from the on the limiter sound ( I call it stutter) and get to fat side turn rich for four stroking IMO. Counterclockwise open the H up fat to hear 4 stroking.
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Some saws four stroke up to and beond limiter.
Others are happy long before limiter hits.
Setting saws after performance rather than rpm can present real surprises.
Harder to hear in higher rpm's than lower.
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I is also easier to hear the high end 4 stroking if you are wearing ear plugs. On my 2007 372 I have a hard time telling the limiter from the 4 stroke, the only way I can do it is in the wood. Any way I also ordered a tech tach 20k I need a new toy to play with.
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The only saws I seen 4 stroking and hitting the coil limiter to date was the poulan 505 475 I have. Their dang rev limit coils was around 10something. If I remember right. Crazy low.
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The only saws I seen 4 stroking and hitting the coil limiter to date was the poulan 505 475 I have. Their dang rev limit coils was around 10something. If I remember right. Crazy low.
That is really low. Like a demo saw coil.
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The only saws I seen 4 stroking and hitting the coil limiter to date was the poulan 505 475 I have. Their dang rev limit coils was around 10something. If I remember right. Crazy low.
That is really low. Like a demo saw coil.
Cant remember but thinking both got the partner 5000 coils afterwords. The ones for 55 51 etc work in them too.
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Good thought to measure before replacing OEM coil! I have run into aftermarket coils that do not have the mounting bolt holes in exactly the same places as the factory coils and sometimes even the core elements are off by a little in relation to the mounting pattern, so you may end up with a ignition timing change just by bolting the thing into the saw! Don't see this much on the later Chinese made coils but did see it a lot in the earlier ones.
You might also want to consider snooping around for a used OEM coil, then you know that the thing is built the was HVA intended it to be built.
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That is why I am going to check the timing before I take the oem one off, just mark it with a permenant marker at low and high rpm. and see where the new coil is at. In the video it was about right in the middle and didn't change with rpm. Hard to say if you could notice the difference in 2 or 3 degrees either way? You would need a dyno or someone timing your cuts with a stop watch.
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There's a thread around here somewhere - a well respected guy was using a timing light. It gave a arbitrary reading, not what I would consider to be a actual reading. It worked out OK for him, for he timed the new type coil to the same number.
My experience with hopping up weed whackers, they are most often in the 22-25 degrees advanced range with the stock flywheel and coil. I put hall effect triggered electronic ignitions with computer controlled timing advance. The total advance I used was 28 degrees with an error towards a little more advance. A 25 -30 cc weed whacker did OK with a fixed advance at 28 degrees but getting into chainsaws above 40cc you need retarded timing to get the engine going of somewhere around 16 degrees without kickback. I always timed them statically with a degree wheel. They timing curve was not too scientific as they were full advance by 5500 rpm.
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How do you check timing statically with a degree wheel on something without points? I didn't think you could? I did it all the time with old cars.
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The moment the magnet leaves the coil armature