Timing Advance s- When \ When Not To Do - Questions

[Adirondackstihl]

I wouldn't want to advance the timing on a milling saw if it were belonging to me.

 

[Chainsaw Jim]

I wouldn't want to advance the timing on a milling saw if it were belonging to me.

Is this something that comes from experience or a scary thought? I've wondered about this. Would it run too hot? Or would the enlarged muffler openings increase enough flow to balance that out?

 

[Adirondackstihl]

Is this something that comes from experience or a scary thought? I've wondered about this. Would it run too hot? Or would the enlarged muffler openings increase enough flow to balance that out?

Milling is hard enough on a saw as it is. Last thing I would want to do is increase internal temperatures, particularly on a milling saw.
Cookie cutter, hot landing or felling saw.....well that's another story I guess.

 

[Chainsaw Jim]

Milling is hard enough on a saw as it is. Last thing I would want to do is increase internal temperatures, particularly on a milling saw.
Cookie cutter, hot landing or felling saw.....well that's another story I guess.

So if it's just speculation then why not put it to the test? I don't see any harm coming to the test subject since it's a test to see if it is able to reach critical temperatures and not withstand them. If it gets anywhere close then just shut it down and it can be confirmed. I've been wondering about advancing timing on large milling saws (880's) with port jobs and this is something that hangs my mind up just the same. I don't have a way to test this out so I can only hope someone else does so we can learn from that.

 

[Adirondackstihl]

Just outta curiosity? Or?

Cause otherwise I see no advantage in advancing the timing on a ported 088/880 just for milling. How much more board feet you gonna get outta that saw and at what expense to the life of the top end. Point of diminishing returns.....

Just my opinion.....

 

[Moparmyway]

It doesn't know the difference. It knows the time between the last two pulses and then flashes light X/720 seconds before a predicted pulse. It's 720 because the spark plug only fires once every two revolutions on a four stroke. For a two stroke it would have to be X/360 seconds before or you can just multiple the dial number X by 2.

I'll switch between 2 and 4 cycle the next time that I am timing something and see how the mark responds at the same RPM

In a typical car motor, the distributor turns at 1/2 of the crank speed, so I hear what youre saying, but it dont make sense to me in my pea brain.

On 4 stroke OPE, the plug fires every revolution, whether its on the power stroke or the exhaust stroke

 

[mdavlee]

I've used saws with almost half a key of advance milling. The only one that would diesel was a 395 when it was in the 90s ambient and would run almost a full tank of fuel per cut.

 

[RIDE-RED 350r]

I'll switch between 2 and 4 cycle the next time that I am timing something and see how the mark responds at the same RPM

In a typical car motor, the distributor turns at 1/2 of the crank speed, so I hear what youre saying, but it dont make sense to me in my pea brain.

On 4 stroke OPE, the plug fires every revolution, whether its on the power stroke or the exhaust stroke

Absolutely true! Only I would correct one small error in your comment: most 4-stroke small engines fire every revolution, at X-degrees BTDC of compression stroke and X-degrees BTDC of exhaust...

Most of your more recent 4-stroke small engines now use an external coil mounted adjacent to the flywheel, fired by the magnet on the flywheel, just like our 2-stroke stuff. There is a "wasted" spark at X-degrees BTDC of the exhaust stroke. Doesn't hurt a thing, so why not simplify the ignition systems on small 4-stroke engines. No more cam or crank driven points to go bad, no more condensers. Just spin the flywheel

 

[srcarr52]

I'll switch between 2 and 4 cycle the next time that I am timing something and see how the mark responds at the same RPM

In a typical car motor, the distributor turns at 1/2 of the crank speed, so I hear what youre saying, but it dont make sense to me in my pea brain.

On 4 stroke OPE, the plug fires every revolution, whether its on the power stroke or the exhaust stroke

That's know as a wasted spark ignition setup and would act the same as a 2 stroke according to the dial on the timing light.

 

[Moparmyway]

That's know as a wasted spark ignition setup and would act the same as a 2 stroke according to the dial on the timing light.

But that still leaves the distributor spinning at 1/2 the crank speed in a conventional distributor setup

 

[jmssaws]

Just outta curiosity? Or?

Cause otherwise I see no advantage in advancing the timing on a ported 088/880 just for milling. How much more board feet you gonna get outta that saw and at what expense to the life of the top end. Point of diminishing returns.....

Just my opinion.....

A small ignition advance will improve efficiency and reduce heat.
I've check lots of saws after long cuts and for the most part a ported saw with a big muffler outlet will run cooler than the stock one.

Of course everything is to a point.

 

[RIDE-RED 350r]

But that still leaves the distributor spinning at 1/2 the crank speed in a conventional distributor setup

Correct. Unlike the currently used "wasted" spark type simplified ignitions on most small engines these days, a dizzy is still driven 1:1 by the cam which is driven 1:2 by the crank. (1 being the cam, 2 being the crank)

But in talking about timing lights, it escapes me as to why it matters whether it is checking ignition timing on a 2-stroke or 4-stroke. Ignition is still occurring at X-degrees BTDC. It shouldn't care whether it's happening on the exhaust or compression stroke, or whether it is reading a 2 or 4-stroke... My timing light just hooks on a plug wire, then to the battery, and flashes each time the plug fires.. It doesn't matter if it's picking up a wasted spark on the exhaust stroke, the timing is still what it is. It doesn't change.

 

[jmssaws]

My timing light is the same.
It's not a super fly one,just flashes when the plug fires.

 

[merc_man]

Here for the info.

 

[Chainsaw Jim]

Just outta curiosity? Or?

Cause otherwise I see no advantage in advancing the timing on a ported 088/880 just for milling. How much more board feet you gonna get outta that saw and at what expense to the life of the top end. Point of diminishing returns.....

Just my opinion.....

So experimenting to prove or disprove your theory is pointless?
What if it actually increases the lifespan of the saw? If that's a possibility then I think it would be important to find out.

Plus there are those who've never used a regular chain with 20 degree teeth for milling to find out they cut better than the 5 or 10 degree teeth they use for milling chains...giving the impression that adding horsepower may seem counter productive on the health of the saw.

 

[merc_man]

I simply used a timing light , marked a fin on flywheel, mark tdc as shown in my pic above, started the saw (warm), and removed the recoil cover. Trigger the light and mark where it flashes.

Just hook the light to a battery and to the plug lead.

Just wondering if you or anyone else may have a video of how to use a timing light. That way those of us who dont understand them can mabe learn a bit better by a vid.
Thanks

 

[jmssaws]

Just wondering if you or anyone else may have a video of how to use a timing light. That way those of us who dont understand them can mabe learn a bit better by a vid.
Thanks

I'm sure there's lots of them on utube.
Search for it

 

[VinceGU05]

Most saws benefit from a little advance, but if you dont notice a better cutting machine, its only a dollar or so for a new keyway and youre right back to stock

rotate yr key and its back to stock.

 

[Brewz]

I personally am concerned that the extra heat and force created by a timing advance would be detrimental to the saws health while milling with a long bar.

I run my 066 with about 1/3rd of a key with shorter bars for cross cutting and it runs great.

I guess what I was wondering was would it be a good idea to pop the flywheel and rotate the key to retard it back to stock when running a long bar milling.

Thinking about that its probably pointless because I will just make the saw less efficient.

 

[mdavlee]

I've milled with ported ones with the key advanced 1/3 or close.