Gap between magneto coil and magnets. Husqvarna 357xp - and probably other models. 544047001 54404703

[fhinson]

My Husqvarna 357xp refused to restart when fully heated. When I thought of getting the plug out before it cooled down again, I found there was no spark. I diagnosed a faulty coil and ordered an aftermarket part listed as suitable for my saw. Following the instructions in the workshop manual, I set the gap on the lower two metal "pegs" that face the magnets. However, this left the top peg with a huge gap and I couldn't get a spark. The old coil was a Swedish made part (SEM) and all three pegs had more or less the same gap once the lower two were set. It was marked 544 04 70-03. Husqvarna say the currently available part that should fit my saw is numbered 544 04 70-01. I got another aftermarket part that was supposed to be compatible with that number, but it was identical to the first one I got and had the same problem. Rang Husqvarna again. All they could advise was to fit a genuine part. I may have to do that, but reluctant, due to cost.
Can anyone tell me if the genuine OEM part 544 04 70-01 places all three pegs of the coil the same distance from the magnets, or does the gap need to be set in a different way?

 

[frank_]

grind a bit off the middle leg maybe ?

 

[old guy]

Leave the screws loose, put a thin business card over the magnets, turn flywheel & card under the coil, let the magnets pull the coil against the card, tighten screws, turn flywheel remove card, yer done.

 

[Mad Professor]

Chinesium coils..............who would have thought they don't fit right?

 

[fhinson]

grind a bit off the middle leg maybe ?

Not a bad idea. The Chinese parts are so much cheaper I could easily afford to give it a try, rather than sending it back for a £12 refund.

 

[huskihl]

The top leg has a larger gap. Center the two magnets on the two bottom legs and use the business card and it should work fine

 

[fhinson]

The top leg has a larger gap. Center the two magnets on the two bottom legs and use the business card and it should work fine

The thing is that the gap is much larger on the top leg - about 3mm. On the original one that I took off it was only a fraction bigger than the gap on the two bottom legs that I set up as you and the workshop manual recommend - and it did not spark after doing that.

 

[huskihl]

The thing is that the gap is much larger on the top leg - about 3mm. On the original one that I took off it was only a fraction bigger than the gap on the two bottom legs that I set up as you and the workshop manual recommend - and it did not spark after doing that.

It only uses the bottom 2 legs to fire.
350, 346, 357, 365, 372, 390….all the same. The top gap is always larger. The bolt holes in the coil aren’t slotted enough to get the top leg to gap correctly

 

[fhinson]

It only uses the bottom 2 legs to fire.
350, 346, 357, 365, 372, 390….all the same. The top gap is always larger. The bolt holes in the coil aren’t slotted enough to get the top leg to gap correctly

Thanks for your further comment, Kevin. Do you know if that is the same with the genuine OEM part numbered 544 04 70-01? The difference in the top gap after setting the lower two was minimal on the original part numbered 544 04 70-03 that I want to replace. On the Chinese part, it is a big difference and I can't get a spark out of it, after carefully adjusting the gap on the lower two pegs, as you recommend. Everything else must be fine, as I can refit the old part and get a good spark; it only fails when the saw gets fully heated up. Would you buy a genuine OEM part - costing about 5x as much in the UK?

 

[huskihl]

Thanks for your further comment, Kevin. Do you know if that is the same with the genuine OEM part numbered 544 04 70-01? The difference in the top gap after setting the lower two was minimal on the original part numbered 544 04 70-03 that I want to replace. On the Chinese part, it is a big difference and I can't get a spark out of it, after carefully adjusting the gap on the lower two pegs, as you recommend. Everything else must be fine, as I can refit the old part and get a good spark; it only fails when the saw gets fully heated up. Would you buy a genuine OEM part - costing about 5x as much in the UK?

First I’d hunt for used OEM, I believe. The 3 series had to be pretty popular over there. The coil from a 350 is the same thing and there were millions made

 

[huskihl]

First I’d hunt for used OEM, I believe. The 3 series had to be pretty popular over there. The coil from a 350 is the same thing and there were millions made

Doesn’t surprise me at all that the Chinese one doesn’t work

 

[huskihl]

Kevin. Do you know if that is the same with the genuine OEM part numbered 544 04 70-01?

I’ve only worked on a couple with aftermarket coils. The other couple hundred were Oem. All the same though, as far as using the bottom 2 legs

 

[J D]

My (neglected) 357

 

[fhinson]

My (neglected) 357
View attachment 913236

Thanks, JD. (Oh to be in New Zealand, where Covid has not been allowed to screw everything up! My daughter is working in Christchurch.) It's very helpful to see that photo, interestingly with another OEM part number. It looks like the gap is quite wide on the upper leg. I presume that it is still sparking, even if a bit buried in sawdust? Mine was worse than that when I first got to it, but still sparking when cold.
I'm attaching an equivalent image of the Chined coil, as fitted.

 

[J D]

I can't attest to the originality of that coil as I'm not the first owner, but it runs well sawdust & all.
I've just had a rummage through a box of 390 bits & the coils I have (blue & black) all have similar clearance.
It might just be the angle but there doesn't look to be much gap on the main pickups in your photo. The gap on the top is definitely greater than OEM though.
Have you tried complaining to seller of the coils?

 

[fhinson]

I can't attest to the originality of that coil as I'm not the first owner, but it runs well sawdust & all.
I've just had a rummage through a box of 390 bits & the coils I have (blue & black) all have similar clearance.
It might just be the angle but there doesn't look to be much gap on the main pickups in your photo. The gap on the top is definitely greater than OEM though.
Have you tried complaining to seller of the coils?

I sent back the first one that I got. I then bought another one from another supplier, which was sold as compatible with the more recent OEM part number advised by Husqvarna UK. However, this was an identical part to the first, with exactly the same part number and ? trade mark symbol stamped on it. Not surprisingly, its physical dimensions were exactly the same as the first.
Judging by the numbers and layout of same, I would say you coil is an original one, probably made by SEM of Sweden, probably for a saw made in 2004-6. The first four digits of the serial number on your saw will show the year of manufacture. Mine is a 2010. Husqvarna UK told me that the OEM part number of the coils had changed several times during the production run of the 357xp. However, the physical dimensions of the flywheel had not changed, so they expected that the physical dimensions of the coils would be the same, just with upgrades to the electronics.

 

[J D]

Yes, my coil is OEM, I'm just not sure it's original to the saw or been pilfered off something else. Many of the husky coils interchange but things like advance curve & lead length might vary slightly & (as you mentioned) revisions/improvements in electronics

 

[fhinson]

Final outcome: I returned the first coil and was refunded. I then bought and got refunds on two more. All were sold as being suitable for the 357xp. The second was sold as being equivalent to the later OEM number, but was exactly the same as the first, even down to markings and numbers on it. The third one was said to be compatible not only with the 357xp and other saws of that era, but also with a later Husqvarna model. The package labelled it as being made in Taiwan, rather than China; it had a different part number on it, but all other external aspects of it were identical. All three had the same issue with the length of the legs. Two of them would not even fit in the space provided.
One of the suppliers refunded me without wanting me to return the item. My brother later carved some of the plastic from the body of this one with his penknife, so that it would fit in the space and allow the screws to be inserted. We were able to gap the middle leg to specification. We reduced the huge gap on the upper leg by accepting a gap on the lower leg that was quite a bit larger than specified. It then produced a spark and the saw is running OK. Whether or not it would run any better with the OEM part, I cannot say.
Conclusion: The very cheap Chinese/Taiwanese coils available in the UK at least for the Husqvarna 357xp are poor copies of the OEM parts, even to the extent of major discrepancies in the dimensions. However, with some modifications, they may be made to function. If I was earning my living with a chainsaw I would probably buy a genuine part. I will follow the advice of Huskihl above and look out for a used OEM part. My experience confirms that failure of the coil/ignition module is a cause of difficulty restarting a chainsaw when hot.

 

[cuinrearview]

The very cheap Chinese/Taiwanese coils available in the UK at least for the Husqvarna 357xp are poor copies of the OEM parts

I try to tell folks...

Most likely you still have an inadequate spark due to the coil gap being out of spec. That may be why it runs "ok". Lots of folks are perfectly fine with their equipment running "ok" if they can save a buck. But was two weeks of dicking around with the saw and the Chinese really worth it?

Here's an OEM coil. If you're not in a hurry and keep an eye out on ebay once or twice a week you can find a better price.

https://www.ebay.com/itm/1539122554...9iAwRcoBXTystGD3G0sO|ampid:PL_CLK|clp:2334524

 

[Duane(Pa)]

A bit odd to come looking for advise, then not following it. Good Luck!