parrisw
Tree Freak
Pretty worried EH Brad!
Ms660
- Thread starter ST98
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Pretty worried EH Brad!
MTNBOY
ArboristSite Operative
I'm not trying to convey I'm as good as brad or randy. Simply make my work saws work better that's all I do. The secrets was a joke. I don't have any and iv got most my knowledge from brads posts
parrisw
Tree Freak
There are many people on here that know what their doing. The whole secretive thing is kinda a big joke to me, and I didn't realize you were joking about it.
MTNBOY
ArboristSite Operative
Its all good. I built that 066 and used brads porting a 660 thread like a bible. As we know he knows his saws.
You better go back in it with Randy's "new" recipe
I'm going back in my 064/066 one of these days. The popup piston in it will be replaced and the squish band cut. Everything else will probably be left as is.
I'm going back in my 064/066 one of these days. The popup piston in it will be replaced and the squish band cut. Everything else will probably be left as is.MTNBOY
ArboristSite Operative
Might look into that. For now I mainly just port them and fix other peoples ethenol issues. I think the one thing that really helped mine was taking the bottom transfer to the case
Mastermind
Work Saw Specialist
You better go back in it with Randy's "new" recipe
I can't take any credit for coming up with anything new. Wiggs is the guy that started me thinking about less exhaust timing. I was on the wrong track with thinking less intake....therefore more base compression was the ticket. It seems that the more I learn the less I truly understand about these two strokes.
mtrees
ArboristSite Guru
My monkey with a gun 660 is BAD that's all I can say!! Thanks Randy!!
MTNBOY
ArboristSite Operative
So ur lowering the port to leave it in the power stroke longer?
Mastermind
Work Saw Specialist
A quick and dirty explanation.....Higher exhaust builds more rpm at the expense of torque. Torque is what drags the chain through the wood so that's what I'm after when I build an engine. If the engine has enough torque, a larger sprocket can be used to increase chain speed. A win win situation IMHO.
MTNBOY
ArboristSite Operative
Correct but by getting more fuel in the cylinder you also get a cleaner charge on the up stroke. That's why I went with making the transfers plenty large and smooth to flow the most mix in and push exhaust out. I know everybody says not to smooth them for atomization but you have to think that the mix going thru a crank spinning 12k plus isn't gonna have time for fuel to settle. So I go with flow volume. Also if your carb should attomize fine if you have it cleaned out and a good impulse line. Am I way off. I know in the race cars we always had all ports mirror finish and still do to this day.I'm just brainstorming trying to figure out how I wanna port this 460 I got sitting waiting for some work
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Mastermind
Work Saw Specialist
You won't really run into this on the 066/660 but too much transfer area can kill torque and make the saw only fit for cutting small wood. If the transfers are too large through the tunnels velocity suffers.
I slick everything up fairly well from carb bore to exhaust outlet.....but I don't polish the intake or transfers. I generally use a diamond burr as that finish is a good compromise and I can level and blend without getting the finish too smooth.
On the 660 get the exhaust as low as possible and the transfers at 120 - 118 atdc. The intake will end up at 84 - 85 atdc if you do machine work. Advance the timing .025 at the key and smooth the carb up by thinning the throttle blade screws and thinning the shafts.
MTNBOY
ArboristSite Operative
I didn't change the top transfer and only took off a bit up the tubes. I'm not to the blueprinting stage but maybe one day. Was trying to pick your brain for some knowledge. Thanks
MTNBOY
ArboristSite Operative
Got time to explain how to advance timing at the key? Will this help one that I didn't cut the head down. Do you pull the flywheel and cut .025 off one side and add some to the other?
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komatsuvarna
Arboristsite MVP
I've played with ignition timing on a few saws in the past, but lately I've been leaving the spark timing stock. I'm forced to run 10% ethanol fuel, and with a saw already pumping close to 200 psi, It just makes me feel a little better with the timing not advanced. Depending on the saw, some gain a little, some gain none, some even lose......with no room for a little error with max ignition timing. My opinion any ways
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MTNBOY
ArboristSite Operative
Good to know. I'm curious what's best port setup for milling?
parrisw
Tree Freak
Low wide ports, with no huge compression.
MTNBOY
ArboristSite Operative
See I did this on my 090 I opened it width and measured it out and ran no base cause my squish was like.04 andwithout had me at.034 I think been abit ago
Boogieman142
ArboristSite Guru
so...anyone know where I can find me a coil for a 660 with poly flywheel? It wants to backfire when starting, pretty rough on the wrist.
MTNBOY
ArboristSite Operative
Let me check might have one off a 066 if you don't want a restricted one
