Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Husqvarna => Topic started by: eriksat1 on February 08, 2014, 11:35:59 am

Title: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 08, 2014, 11:35:59 am
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 11:40:16 am
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 08, 2014, 11:45:48 am
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
Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 11:53:18 am
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.  ;)
Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 11:56:55 am
video is Mitch, mweba his username here.
Title: Re: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 08, 2014, 12:38:55 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: Magnus on February 08, 2014, 12:50:04 pm
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.


Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 01:07:17 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: Magnus on February 08, 2014, 01:16:19 pm
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.

Title: Re: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 08, 2014, 02:03:10 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 02:31:52 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: Eccentric on February 08, 2014, 03:00:16 pm
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. 
Title: Re: Unlimited coil for 372xp timing?
Post by: Cut4fun on February 08, 2014, 03:08:21 pm
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. 
Title: Re: Unlimited coil for 372xp timing?
Post by: KilliansRedLeo on February 13, 2014, 09:33:25 am
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.

Title: Re: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 13, 2014, 12:31:08 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: 660magnum on February 13, 2014, 12:52:09 pm
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: eriksat1 on February 14, 2014, 10:27:35 am
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.
Title: Re: Unlimited coil for 372xp timing?
Post by: 660magnum on February 14, 2014, 10:46:23 am
The moment the magnet leaves the coil armature