Testing different timing advances on tree monkeyed 661

[David Young]

Thank you for testing with a scientific method

 

[jmssaws]

Thank you for testing with a scientific method

Everything I test seems to conflict and confuse,it's hard to take what works on one saw and have it work the same on another.
Mtronic is probably more consistent though.

I got a box of 064 flywheels that you can line the keys up on and the magnets are all over the place.

 

[Mastermind]

There are three different 064 flywheels even without variations in those three. It can get confusing.

 

[Nitehawk55]

That's why some of those 064's kick back like mules !

 

[Nitroman]

This is all nice, and you put a great deal of effort into it, but if you want truly meaningful results, you must devise a way for the saw to be held not by a human being. You need a fixture to hold the saw, then let it fall through the wood on its' own. In this fashion each successive cut is exactly the same except for those factors you introduce; chains, bars, or oils.

 

[Moparmyway]

Would be curious if there were any gains on a manual carb and euro coil on the 661

I ran a .045 key with M-tronics. The same key was spark knocking after a long cut with a 25"/404 setup with Euro coil and WJ69 carb. I tried .050 and still heard it after a long cut with s 36"/404 setup.

I'm running a .055 key now with the Euro coil and WJ69, and all is well

 

[jmssaws]

There are three different 064 flywheels even without variations in those three. It can get confusing.

Yeh but I checked the same ones.

I have several limited flywheels if for some reason anybody need one.
I Mark them and run it without a key but would like to re-broch them.

 

[bennne]

By euro coil do you mean a non mtronic coil or a differently programmed mtronic one?

 

[Mastermind]

By euro coil do you mean a non mtronic coil or a differently programmed mtronic one?

Non-mtronic

 

[Moparmyway]

Mine is Back to m-tronics now

Put in a new piston & rings, also did some more port work

First few cuts on the first tank

404 with an 8 tooth in a hard, solid crotch

 

[awol]

How many degrees of advance does each key represent? I have done some experimenting with a new, box stock 661, and it runs best at about 10 degrees advance; a ported one would likely be different. I simply spin the engine up against a piston stop, pull the flywheel and key, turn the flywheel forward 10 degrees and lock it back down.

 

[Mastermind]

How many degrees of advance does each key represent? I have done some experimenting with a new, box stock 661, and it runs best at about 10 degrees advance; a ported one would likely be different. I simply spin the engine up against a piston stop, pull the flywheel and key, turn the flywheel forward 10 degrees and lock it back down.

In a flywheel that size, .020" is about 8° of rotation.

 

[Keith Gandy]

In a flywheel that size, .020" is about 8° of rotation.

Randy is there a paticular way u figure that?

 

[junkman]

Here is a good video Mitch did using an automotive timing light to check timing .

 

[Keith Gandy]

Id say find TDC with piston stop and degree it, cut the key and retighten against stop and read degree wheel again would be my guess

 

[Marshy]

This is all nice, and you put a great deal of effort into it, but if you want truly meaningful results, you must devise a way for the saw to be held not by a human being. You need a fixture to hold the saw, then let it fall through the wood on its' own. In this fashion each successive cut is exactly the same except for those factors you introduce; chains, bars, or oils.

I partially agree with you. I do the think it's necessary to remove the human factor but instead control the amount of load on the saw. Rpm in the cut can be used as the primary indicator of load on the engine. If he can sustain xx,xxx rpm during the cut for each test then the saw is loaded the same for each. The time in the cut will vary based on more/less efficient engine performance. Having a large chunk of wood with a long cut time also would help reduce uncertainty because entering and exiting the cut varies a lot so that variable is reduced as compared to the actual loaded cutting time. Just my 2c.

 

[awol]

Id say find TDC with piston stop and degree it, cut the key and retighten against stop and read degree wheel again would be my guess

Yes, that works well. What I do is scribe flywheel at tdc in relation to coil pole, and then scribe every two degrees from there using a degree wheel. The scribes are real handy for future timing experiments, don't have to put a degree wheel back on.

I like the timing light method, but have never used it yet. It will let you see what the advance curve is, if any.

 

[Keith Gandy]

Yes, that works well. What I do is scribe flywheel at tdc in relation to coil pole, and then scribe every two degrees from there using a degree wheel. The scribes are real handy for future timing experiments, don't have to put a degree wheel back on.

I like the timing light method, but have never used it yet. It will let you see what the advance curve is, if any.

Great idea. Thanks

 

[Mastermind]

Randy is there a paticular way u figure that?

File and check with a degree wheel.

 

[jmssaws]

A 040 key in the 661's I've been playing with is to much,in a few cuts time it will have hole in the crown on the exhaust side from detonating.

I opened squish on one and it stopped
Backed it off 010 on the other and stopped it.
4700 coil though