044 project

[MustangMike]

I will defend Matt's point of view here, even though a little timing advance may give it more power. Matt is right that the "operating range" may change, and the saw may also get harder to start. So if his saw performs like he wants it to, then it is fine.

Matt's rational is sound.

Higher RPMs may shorten the life of the saw, and he may be getting more torque with the timing where it is. Some high performance saws get "peaky" and don't hold RPMs under load.

Also, harder to start in cold weather is no fun.

 

[blsnelling]

Baah humbug They start very easily.

 

[MustangMike]

When temps drop, even a 044 can bite ya. Remember a guy on the other site saying he "retarded" the timing on em to make em easier to start!

 

[MattG]

I do understand the reasoning behind the timing advance, i.e. start the burn earlier and get the max. pressure in the jug right after TDC crossing.

I'm still leaving it for now, though, but thanks. Still I'll have plenty of fun with it in it's current guise.

FWIW, me being me, I did a shed load of research on ign. timing in the last 24 hours.

So fair enough, as revs rise, you may want a bigger adv. angle, due to shorter revolution period. However, what I also read was that increasing the temperature or pressure of operation will accelerate burn time.

I'm sure that some of the work I've already done (BG gone i.e. higher CR, and tighter squish) will mean that burn time at peak will be reduced, reducing the need for such an advance.

But in absence of a dyno and a high-rpm digital strobe, I guess I'll never know!!

 

[blsnelling]

May the force be with you! Don't fear the RPMs.

Go to the 2:10 mark.

BTW, don't take me wrong. I'm just encouraging and having fun with you.

 

[MattG]

BTW, don't take me wrong. I'm just encouraging and having fun with you.

Ha ha!

Ditto, I just wish I had all the big wood you yanks do!

 

[MattG]

@blsnelling

Out of interest, have you ever used a degree wheel and a suitable reference on the f/wheel, to figure out what advance you are actually making when you do the key shave?

Last night, I didn't quite have the time for that, but I used my friend "Maths", and I figured that for a crank stub of ~12mm diameter, and a shave of 0.5mm, you get about 5 degrees of rotation. Which is coincidental, since I also read the 044 manual,



and noted that 5* is exactly the level of tolerance that the stihl ignition module is presumably manufactured with.

 

[MustangMike]

I believe Randy checked a .020 shave on a 461 and measured a 6 degree change, so we are all in the same ball park.

However, technically, it is the small end of the crank that will hit the shaved area first, since we do not angle our filing (as technically we should). However, in the real world, there is enough "play" so it does not work out that way. (I have also attempted to do the calculations).

(The larger the circumference, the larger the change needs to be for the same degree change)

I generally go .020 to .025. I think a lot of people err on a little too much advance, and I would rather do the opposite.

I backed the timing off a ported saw I had (back to only .020) and I believe the saws was "less peaky" after that (had better mid range torque). The saw had previously been advanced more than 1/2 the key. When you are trying to avoid chain pinches (in the real world) as opposed to cutting cookies, I'll take the increased torque any day of the week.

 

[blsnelling]

@blsnelling

Out of interest, have you ever used a degree wheel and a suitable reference on the f/wheel, to figure out what advance you are actually making when you do the key shave?

Yes I do. I generally advance them 6°-8°.

 

[MustangMike]

Yes I do. I generally advance them 6°-8°.

Which equates to how much off the key???

 

[blsnelling]

Which equates to how much off the key???

It depends on the diameter of the flywheel. Generally, .020" will get you in the ballpark. On saws with a cast in key, I simply grind it back about 1/3 and lock it in place using a degree wheel to set it.

 

[MustangMike]

It depends on the diameter of the flywheel.

Thanks for the response, appreciate it.

However, not to pick, just for clarification, it depends on the diameter of the crank. 5 degrees on the crank will be 5 degrees on the end of the flywheel. Just picture a slice of pie with the point being in the center of the crank and you will see what I mean. The larger the circumference, the more distance is required for the same # of degrees.

 

[blsnelling]

Correct.

 

[Wonkydonkey]

But-o-but, I'm sure we are well aware as mattG said engerneering tolerances 5*!, I guess that why some like more and some like less, (a saw pullin-ya-digits off when starting)

 

[Adamski]

But-o-but, I'm sure we are well aware as mattG said engerneering tolerances 5*!, I guess that why some like more and some like less, (a saw pullin-ya-digits off when starting)

Worst saw ever to do this was my 254xp of all saws. It was after I did a base delete and new piston and ring. I was not expecting it to be THAT different and ill prepared for 54cc SnapBack. Hahaha. and it wrecked my hand more than my old 181se.

 

[MattG]

I believe Randy checked a .020 shave on a 461 and measured a 6 degree change, so we are all in the same ball park.

I knew my maths was still good!

I was not expecting it to be THAT different and ill prepared for 54cc SnapBack.

Hmm... yuk!


Well, I did more reading. Apparently when charge is less dense, e.g. with higher vacuum at idle, the motor appreciates more advances. (Molecules further apart burn slower - makes sense).

So.....and this will piss Brad off, perhaps I will experiment, since the idle on that hybrid is awfully lumpy!

 

[MattG]

If I get time this weekend, I'm gonna try @BonScott46 's idea of a log rack, and perhaps stack up some of my birch limbs, so maybe I'll be able to entertain you all with more vids.

 

[J_M____]

If you have a few flywheel keys, try some different amounts of advance. I tried .010,.020,.030 on my 440. Each saw is different.
Once the coil is gapped correctly to the flywheel, don’t move it when changing keys. The holes in the coil are bigger than the bolt and you can change the timing a little since there is some play.

 

[MattG]

Have done some sawing today. I did experiment with Kyle's idea of log rack, but I'm afraid that my skills/patience in that particular area are lacking. I did a couple vids, however most were either unimpressive, or poor advertisements for my health+safety awareness.

I turned the H screw in a tiny amount, and the tacho is now saying 14.9K. Saw is clearly a rev-hungry monster.

This one wasn't much fun really, and arguably not the best way to make firewood, but I think a couple of times the saw gets a reasonable load on it.

 

[blsnelling]

That's a good tune. It still readily 4-strokes.