How much ignition advance?

[calamari]

Have you never used a timing light. I live at fairly high altitude so I plan on at least a few degrees advanced. If you have TDC then take a degree wheel and scribe five and ten degrees which is pretty much all you need. Go too far and you should feel a rattle or vibration. Back off and it should smooth right out. Thanks

I'm 77 and have used multiple timing lights which as you may recall requires a distributor that you can rotate as you describe. There is no easily adjustable timing advance/retard mechanism on any saw I've seen. It always requires the saw to be partially disassembled to adjust when the timing fires. If what you say is disassembling the saw, marking a line at 5 degrees and 10 degrees (which seems way more than you'd want to increase the timing to) moving the coil in an advance direction some fraction of those marks, assembling the saw, run it, feel it rattle, disassemble the saw, adjust the timing, and do that until it doesn't rattle when up to full operating temp and you'll have a process only slightly shorter than this sentence. Do that so it works at high altitude and you run the risk of detonation and seizing at lower altitudes.
If what you meant was to advance the timing and then adjust the mixture to a setting that's smooth, it may make more sense but I still don't think you'd know how much advance you have. How does a timing light come into play?

 

[calamari]

I get what calamari is saying. If I'm correct, people don't advance the timing from 2deg btdc to 4deg btdc. They just advance the timing 2 deg. I don't know if there's an accurate way to tell what the timing actually is. But you can accurately measure how much you advance it....I think. I didn't use a degree wheel. I scribed a line on the flywheel, moved the coil, and scribed another line. I then measured the distance between the lines and used the math thing to see what angle it subtended. So I would not know what the exact timing would be but I know I can move it 2.5 deg.​

I understand and appreciate this explanation of how much of an increase you have made to the timing but w/o knowing what the timing is you may be only 1 degree away from detonation before you advance the timing Since factories know exactly how much timing they have on their engines, I'd imagine that they set them at a point where the saw runs well in average conditions allowing it to be used at a range of altitudes. Advance the timing and you now have reduced the altitude window where it runs right and run the risk of the mixture setting not being able to compensate enough should you go to a lower/leaner altitude.
If it works for you I'm unanimous in my support for your position. I'm afraid I still don't see how a timing light provides any useful information other than that the saw's plug fires and you don't need a timing light for that. I get the same info when I ask somebody to hold onto a 16 penny nail I put in the sparkplug wire's boot and then jerking on the starter rope.

 

[3000 FPS]

You know Calamari advancing the timing on a saw is mainly for hot rodding a saw. People who want to port their saws and increase the compression, open up the mufflers and so on and so on. You may not want to do some of these things if it is going to make your firewood saw more unreliable under various conditions.

I have saws that I have modified and I do not take them to the mountains when cutting firewood. I think the OP is just trying figure out how to hot rod a saw and having some fun with it.

 

[3000 FPS]

I took an old Poulan one time a Poulan 3700. I took the key out of the crank and flywheel and took a penny cut it in half stuck that back in there twisted the flywheel CCW and tightened it down and then crank it up to see how it ran. It ran fine but I did not leave it that way because I was getting some kick back when pulling on the starter rope. Good way to break a pulley. But I was just testing things you might say.

 

[calamari]

You know Calamari advancing the timing on a saw is mainly for hot rodding a saw. People who want to port their saws and increase the compression, open up the mufflers and so on and so on. You may not want to do some of these things if it is going to make your firewood saw more unreliable under various conditions.

I have saws that I have modified and I do not take them to the mountains when cutting firewood. I think the OP is just trying figure out how to hot rod a saw and having some fun with it.

Having been a hot rodder all my life I know how much fun comes from experimenting and making things better. I've also blown things up by not having a good grasp of how what I'm doing affects the engines characteristics and longevity. It's a lot cheaper to fix a saw than a small block Chevy but saws can be so frustrating sometimes I thought that if I could understand the process probably anybody can. I still don't get it but it's not important that I do. Just pointing out things to think about before by trying to make things better they are made worse.

 

[cookies]

think of the flywheel as your distributor, one only needs to mark the case in degrees and use a timing light to take notes then modify flywheel orientation to adjust timing. since the flywheel is interface fit the key is not truly required but only for assembly during manufacturing for speed.I learned early on to mark the flywheel and crank snout on saws before disassembly because you never know if the key is gone or altered and if it is altered or if I alter it i can easily set it back to its original timing at just a glance.

 

[John Stryker]

think of the flywheel as your distributor, one only needs to mark the case in degrees and use a timing light to take notes then modify flywheel orientation to adjust timing. since the flywheel is interface fit the key is not truly required but only for assembly during manufacturing for speed.I learned early on to mark the flywheel and crank snout on saws before disassembly because you never know if the key is gone or altered and if it is altered or if I alter it i can easily set it back to its original timing at just a glance.

Do you have to remove the starter and air conductor after you get the saw running in order to check your timing with a timing light? Or maybe drill a sight hole in the starter cover?

 

[Old2stroke]

Since timing lights have become totally useless on modern automobiles, people don't seem to know how to use them anymore and don't have one. Checking the basic timing at low rpm is easy, you remove the plug and externally ground it to the cylinder, connect the light sensor to the plug lead and ground the light to the cylinder (you need a 12 volt power supply for the light). After finding TDC, you make a mark on the FW and a corresponding mark on the engine case, you then drive the engine by connecting a variable speed drill to the FW nut and start rotating it in the right direction. Just turn it fast enough for the light to flash and strobe your marks, you can see where the spark occurs and use some geometry to work out the firing relative to TDC. Spray some WD40 in the plug hole to lub the piston a bit and don't try for higher rpm than necessary. This just checks the current timing, if you want to modify it, you have to go to the clutch side and use a timing wheel or similar device to reference everything to the actual crankshaft and not the FW as the spark will always occur when the FW and the coil are in the same relative position regardless of where the FW is on the crank. Remember this is being done at low rpm where all you are doing is checking basic timing and is subject to change as the electronics in the coil varies the timing with rpm. Checking the timing at high rpm is different as you have to fire up the engine and use a tach to get rpm at the same time you use the timing light to see the spark advance.

 

[Joseph W Santora]

I live at fairly high altitude so I plan on at least a few degrees advanced

Why?

I have saws that I have modified and I do not take them to the mountains when cutting firewood

And why?.....
(I live at 5200ft and typically cut at about ~10k)

 

[3000 FPS]

Why?

And why?.....
(I live at 5200ft and typically cut at about ~10k)

I was up about 8000 ft during the summer and it was pretty warm. My modified saw over heated. I could not get it to restart. But I always take 3 to 4 saws with me and I used one that was just mildly modified and it was fine.
I live at 5000ft and have cut as high as 9k but never at 10k. I am 71 now and getting up around 10000 ft falling trees bucking them up and loading by myself would probably be a little tough. I can still handle the 8000ft level.

So I guess if I have done an all out modified saw I leave those at home and only take a like a woods ported saw.

 

[Jasent]

 

[3000 FPS]

Hey Jasent nice video thanks for posting.

 

[cookies]

Do you have to remove the starter and air conductor after you get the saw running in order to check your timing with a timing light? Or maybe drill a sight hole in the starter cover?

yes you start the saw then remove the recoil to check timing, if you own a second recoil it could be modified with a hole to access the timing marks you make on the case and flywheel

 

[Ted Jenkins]

Why?

And why?.....
(I live at 5200ft and typically cut at about ~10k)

High altitude tuning is kinda important if an OP plans on cutting past 4 or 5,000 feet. A standard saw at 6,000 feet will feel sluggish and not perfect. The proper modifications is to increase compression as much as possible like gasket delete and advance timing from 4 to 10 degrees. At sea level or below oxygen is most concentrated. As altitude increases oxygen decreases thus air fuel mixture burns slower. To give two strokes a better performance curve increase air flow and advance timing helps. If one could super charge or turbo charge motors easy then the air would not matter. Since saws are a simple engine design a couple simple improvements do much for making a saw feel potent at higher altitudes. Thanks

 

[Ted Jenkins]

I was up about 8000 ft during the summer and it was pretty warm. My modified saw over heated. I could not get it to restart. But I always take 3 to 4 saws with me and I used one that was just mildly modified and it was fine.
I live at 5000ft and have cut as high as 9k but never at 10k. I am 71 now and getting up around 10000 ft falling trees bucking them up and loading by myself would probably be a little tough. I can still handle the 8000ft level.

So I guess if I have done an all out modified saw I leave those at home and only take a like a woods ported saw.

A modified saw operating at 10,000 feet should not have too much of an issue at producing its' full potential. At higher altitudes a saw will produce less power and less heat than at sea level. It is possible that maybe you got a lean adjustment more than you thought. Regardless of circumstances I have to force myself to pull the plug to determine for what my tuning is doing. Pretty much all saws will run better with a two to five degree advance. Very easy to make an offset key and a stock one when at lower elevations. Thanks

 

[Joseph W Santora]

My recipe for 10k cutting is base gasket delete, popup piston and a modded muffler. I've not tried advancing the timing but with the mods I do the saws run about the same at 10k as they do at sea level with about the same psi on a compression gauge as they do at sea level.