Ignition coil spark advance?

[KUBOTA OWNER]

I have never thought about if the ignition coil (module) also having the ability to advance the spark?
--I have assumed that if there is no spark then the coil is bad? ----I think I have a echo coil that is
bad because the motor will not accelerate. Starts fine but will not rev over 4000 rpm. I have done everything
except replacing the coil. --- Does the coil on never model saws ect. have electronics to control spark advance?

 

[mountainlake]

Yes they advance the timing around 3o degrees. Steve

 

[KUBOTA OWNER]

Thanks, I never gave it a thought before now. This is on a echo blower that a friend asked me to look at.
I even took it to a dealer and an he had no idea why it ran like that. --I asked him about a coil and he said
no because it has a good spark. ----New coil will arrive on thur.

 

[mountainlake]

A assume you have checked the muffler screen, that would cause low RPM's Steve

 

[KUBOTA OWNER]

Yes, I have removed the muffler, rigged up a different carb. pressure checked and rebuild the carb
about 5 times. Has great compression and runs good until you try to rev it, then it bogs and seems to
blow fuel from the carb. but never stalls. ---Has anyone ever hooked up a timing light to a two cycle
and get it to work? --- You would have to mark the flywheel at TDC and then hook up a 12v battery
to the timing light. I have an inductive pickup timing light and I might try it.

 

[mountainlake]

That sounds like a real good plan. Steve

 

[nmurph]

Fuel line and filter?

 

[w8ye]

Worn piston skirt o intake side?

 

[old-cat]

Yes, I have removed the muffler, rigged up a different carb. pressure checked and rebuild the carb
about 5 times. Has great compression and runs good until you try to rev it, then it bogs and seems to
blow fuel from the carb. but never stalls. ---Has anyone ever hooked up a timing light to a two cycle
and get it to work? --- You would have to mark the flywheel at TDC and then hook up a 12v battery
to the timing light. I have an inductive pickup timing light and I might try it.

I used a longer coil wire so I could connect the light and used an ac 12v power supply/transformer and marked the flywheel TDC

 

[Rookie1]

Some Stihl FS90R trimmers had coils go bad like that. I also had one stay advanced and was a bear to start. Sometimes electronics aren't the best way.

 

[mountainlake]

I sure wouldn't want to see a mechanical advance on a saw. Steve

 

[sachsmo]

Technically the timing doesn't advance, it's just retarded at starting idling etc.

 

[old-cat]

Technically the timing doesn't advance, it's just retarded at starting idling etc.

I'd sure like to get an 046 coil that has retarded advance to start. I bought a used 046 coil from chainsawr.com and checked its timing. NO retard.

 

[KUBOTA OWNER]

I was correct and it was a coil, found a complete siezed unit on ebay and swapped the coil
and wala it runs fine.

 

[MustangMike]

Had to replace the coil on my 044 #2 a little while ago. It would start, but would not run. Almost everyone (myself included) thought it was fuel.

 

[X_makina]

I did a search and found this thread.

I have been running dynamic timing tests on several chainsaws, and I was a bit surprised to
discover that some have fixed timing and some change when revving them up. I shined a timing
light on the flywheel, after removing the starter of a running saw. I suspect that initial timing
is around 20-25 degrees BTDC, and changes gradually to 30 or more BTDC at 5 or 6K RPM. I
plan to take a video and post on YouTube.

Has anyone taken any timing measurements, and if so, on what saw(s)?

So far, I have discovered fixed timing on a Husky Rancher 455, dynamic on a Husky 350, and
dynamic on a Shindaiwa 500. I still plan to test my 2100, a 371, a Tanaka, and another Shindy.
I have one running Poulan points saw, that must be static.

 

[MustangMike]

From what I have heard, instead of "advance" it is a "retard" for starting, and most modern saws have it. Some of the builders have checking timing, but I do not know the details. Also, it seems not every saw is the same, even if it is the same model, there are variations.

 

[X_makina]

From what I have heard, instead of "advance" it is a "retard" for starting, and most modern saws have it. Some of the builders have checking timing, but I do not know the details. Also, it seems not every saw is the same, even if it is the same model, there are variations.

Although I have heard that too, I have seen no data on any specific saw. Retarded timing (ignition fires After TDC) at
start or low RPM would certainly be possible if the ignition has built in spark advance, so the spark moves to somewhat
Before TDC at higher RPMs. Gradually, I assume.

I would like to see something like, "I have a Biffco model N chainsaw and it has, x-deg timing at 2000 RPM, ramping
to y-deg timing at 6000 RPM.

The modern saw I quoted above, the ubiquitous 455 Rancher, has fixed timing, and I am sure it quite a bit advanced. I
will get my degree wheel out and take a measurement.

 

[ncfarmboy]

Has the same problem on a 262 Husky would idle but wouldn't rev over 8600rpm's. New coil good to ggo.
Shep

 

[MustangMike]

Info on Stihl Coils has been posted in the past. It is not really a gradual increase, but more like a couple of steps are various RPMs.

The only important # is the total advance, and it is great to keep that in sync with any mods to the saw. Then you hope it remains easy to start, but it will not always happen that way! Sometimes, you just have to reach a balance.

I have even seen folks retard timing from the original position to make the saw easier to start. The thought makes me shudder, but I also hate a saw that bits me! Cool weather seems to magnify the problem. (thicker oil in the cylinder)