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Sold Stihl 066/660 Cylinder for hybrid
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redbull660
Addicted to ArboristSite
well you want power and you want to run 404. I owned 5 660s and a ported 066. After running the 661 I sold them all.
Plus the port timing numbers on many 660 jugs aren't exactly great for torque. Personally IMHO I think the 661 crank and later 660 cranks are more suited for 404 than a 064 crank.
one of my 661s ... 60" bar .404 full skip
Plus the port timing numbers on many 660 jugs aren't exactly great for torque. Personally IMHO I think the 661 crank and later 660 cranks are more suited for 404 than a 064 crank.
one of my 661s ... 60" bar .404 full skip
redbull660
Addicted to ArboristSite
one of the strongest 066/064s I've ever seen, pulling same bar and chain. This jug had exceptional numbers and scott spent a ton of time tweaking every last ounce of power out of it. I now have 661s stronger than the one in the above video.
I don't have specifics. but iirc side by side you can see a difference. In any case something to double check on before beginning the endeavor.
I don't have specifics. but iirc side by side you can see a difference. In any case something to double check on before beginning the endeavor.
redbull660
Addicted to ArboristSite
triple port muffler mod 660 vs stock 661. 36" bar
Damn, that sure is a beast of a saw. So when you say you have one stronger, do you mean stock or one you've put the works into?
I really appreciate your help in any case, i might give that 661 another thought
I really appreciate your help in any case, i might give that 661 another thought
redbull660
Addicted to ArboristSite
saws above are fully ported by tree monkey aka scott kunz.
661 - but if just tinkering, the muffler mod is a nice gain. max flow air filter is a nice gain but not required. Kind of expensive.
You can mod the air filter cover to help air flow and chip build up. Also you can purchase a prefilter for the 661 filter because the HD2 filters have those deep pleats that no matter what mods you do the dust still gets down in them and stays. The black vents are frogskin. They do snowmobile stuff look em up if interested. Duck tape inside the filter gives you a tighter lock down. Only need 1 or 2 layers.
Timing advance helps on the 661... the typical .02 off the key is good.
could also probably do a gasket delete.
661 - but if just tinkering, the muffler mod is a nice gain. max flow air filter is a nice gain but not required. Kind of expensive.
You can mod the air filter cover to help air flow and chip build up. Also you can purchase a prefilter for the 661 filter because the HD2 filters have those deep pleats that no matter what mods you do the dust still gets down in them and stays. The black vents are frogskin. They do snowmobile stuff look em up if interested. Duck tape inside the filter gives you a tighter lock down. Only need 1 or 2 layers.
Timing advance helps on the 661... the typical .02 off the key is good.
could also probably do a gasket delete.
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redbull660
Addicted to ArboristSite
mtronic has always been fine on everything porting mod we've tried. I'm on my 16th ported 661 with tree monkey. This is a cut and paste answer I gave to someone who asked similar questions...
661 and mtronic problems.
1. solenoid. The one they have had in all the mtronics isn't that great when it gets dirty. They have redesigned it.
the only time I've had an issue with any of the 16 or so 661s I've owned was when Scott and I were taking the carb apart trying stuff. I think it either got dirty or the o ring damaged when sitting out one of those times. The saw wouldn't idle at all. New Solenoid fixed the issue.
IMO most likely what is happening is that dirt and or saw dust is getting into the gas when refueling. The fuel filter is only going to protect you so long. I'd also guess fuel filters aren't getting changed as often as they should. Whatever the case, it equates to dirt into the solenoid. Hopefully the new solenoid will be more tolerant to dirt/saw dust. Because lets be honest, loggers just aren't going to be that careful or change fuel filters often enough.
2. the coil. The coil/control unit has been dissected in another thread on here. Turns out there is a computer board inside the thing. Like most electronics it's good, or going to go bad in the first month or so, or it's good (guys that don't use their saw very much it's not going to show up in a month). Early coils were programmed to let the saw go too lean out of a long cut. This was fixed with the 4701A coil. They have come out with a 4702 coil now but no one seems to know what the improvements if any were made.
3. the intake boot - early on they had the boot and the rubber washers inside would get dislodged. They fixed this with the "Straight" boot.
4. guys not letting the saw warm up. the mtronic seems to force you to let the saw warm up. I don't see why that is unreasonable to so many. You let a race car warm up.
5. guys not letting the saw cool down. Guys that shut down their saws right away. vapor lock comes to mind. Also if you read how the mtronic works. The coil remembers the last known conditions the saw ran in. So if you shut it down at say 7k rpm just out of the cut. And you go to start it up and idle is 3k. I assume its' not going to like that.
What I've done...
I blow off the gas cap before I open it.
On a Cold start I let the saw warm up for about 30 seconds before I start cutting. I go easy on the saw for 2-3 cuts then let er rip.
I let the saw idle for 10-20 seconds before I shut it off.
I modded the air filter cover on the bottom to let chips out. Now I use the max flow filter and have modded the MF cover on the bottom to let chips out.
That's all I've done and I haven't had problems with any of the 16 or so saws.
661 and mtronic problems.
1. solenoid. The one they have had in all the mtronics isn't that great when it gets dirty. They have redesigned it.
the only time I've had an issue with any of the 16 or so 661s I've owned was when Scott and I were taking the carb apart trying stuff. I think it either got dirty or the o ring damaged when sitting out one of those times. The saw wouldn't idle at all. New Solenoid fixed the issue.
IMO most likely what is happening is that dirt and or saw dust is getting into the gas when refueling. The fuel filter is only going to protect you so long. I'd also guess fuel filters aren't getting changed as often as they should. Whatever the case, it equates to dirt into the solenoid. Hopefully the new solenoid will be more tolerant to dirt/saw dust. Because lets be honest, loggers just aren't going to be that careful or change fuel filters often enough.
2. the coil. The coil/control unit has been dissected in another thread on here. Turns out there is a computer board inside the thing. Like most electronics it's good, or going to go bad in the first month or so, or it's good (guys that don't use their saw very much it's not going to show up in a month). Early coils were programmed to let the saw go too lean out of a long cut. This was fixed with the 4701A coil. They have come out with a 4702 coil now but no one seems to know what the improvements if any were made.
3. the intake boot - early on they had the boot and the rubber washers inside would get dislodged. They fixed this with the "Straight" boot.
4. guys not letting the saw warm up. the mtronic seems to force you to let the saw warm up. I don't see why that is unreasonable to so many. You let a race car warm up.
5. guys not letting the saw cool down. Guys that shut down their saws right away. vapor lock comes to mind. Also if you read how the mtronic works. The coil remembers the last known conditions the saw ran in. So if you shut it down at say 7k rpm just out of the cut. And you go to start it up and idle is 3k. I assume its' not going to like that.
What I've done...
I blow off the gas cap before I open it.
On a Cold start I let the saw warm up for about 30 seconds before I start cutting. I go easy on the saw for 2-3 cuts then let er rip.
I let the saw idle for 10-20 seconds before I shut it off.
I modded the air filter cover on the bottom to let chips out. Now I use the max flow filter and have modded the MF cover on the bottom to let chips out.
That's all I've done and I haven't had problems with any of the 16 or so saws.
That gives me some confidence in their system them. Thinking back i ran a couple 261's for work and they all did fine considering the abuse they went through. Well you defintally gave me a lot to think about, might have to sell the ol girl and upgrade. Again, thanks for your help!
Kwood
ArboristSite Lurker
The 066 BB kit from Bailey's works well for the 064 conversion too, and at $130 It's more affordable than oem. I just performed my first one and it went without any hiccup. The 064 bolt pattern is the same left to right looking from handle to exhaust port, but the rear and front are spaced further apart, which requires you to slot the new cylinder holes bringing all 4 in. I had no issues with centering as the piston takes care of it, pretty smooth process. I drilled and tapped the holes for M6 x 25 vs the OEM m5x20, vid here:
Ran out of time for more videos as I was leaving Canada and this was my girlfriends fathers saw so I had to get it done.
I also had to grind on the crank case to fit the oversize piston skirts, you might be okay with a oem 066/660 piston though. The Magnesium case grinds easily enough, I did it with case assembled (just need to take extra good care and precautions to avoid metal filings in the case) and I had very limited tools (chainsaw file and dremel bit in a cordless drill). Also ground the exhaust gasket and muffler to fit the oversize exhaust port, modded the muffler a bit to allow better airflow and installed a much needed decomp valve and drilled the top plastics for said valve. Compression was 185 with a deleted head gasket leaving a .025 squish.
I currently have my own 064 with burnt piston due to a bad crank seal so I'll be doing the conversion again to my saw. The power gain was very substantial as well as a nice deep sound going to the 066BB, it pulled a 36" .404 through anything I could throw at it and it just kept pulling with no bog. Very happy with the conversion and I read the 064 crank is the same as the 066.
Ran out of time for more videos as I was leaving Canada and this was my girlfriends fathers saw so I had to get it done.
I also had to grind on the crank case to fit the oversize piston skirts, you might be okay with a oem 066/660 piston though. The Magnesium case grinds easily enough, I did it with case assembled (just need to take extra good care and precautions to avoid metal filings in the case) and I had very limited tools (chainsaw file and dremel bit in a cordless drill). Also ground the exhaust gasket and muffler to fit the oversize exhaust port, modded the muffler a bit to allow better airflow and installed a much needed decomp valve and drilled the top plastics for said valve. Compression was 185 with a deleted head gasket leaving a .025 squish.
I currently have my own 064 with burnt piston due to a bad crank seal so I'll be doing the conversion again to my saw. The power gain was very substantial as well as a nice deep sound going to the 066BB, it pulled a 36" .404 through anything I could throw at it and it just kept pulling with no bog. Very happy with the conversion and I read the 064 crank is the same as the 066.
Kwood
ArboristSite Lurker
I ran a few tanks through it to break it in, then cut a bit more, then I put it through a 5ft high stack of mid 20 inch oak and almond trunks. Also milled some 3"x33"x16' oak and it was a workhorse.
I can't speak to the longevity of the kit vs oem. From some of the veteran members I haven't heard any flack about the Baileys kit and my research found them to be reliable. The intake and exhaust ports had casting flash that I smoothed out before install, slight variance in squish of about .001-2. Overall it runs great, kicks over every time and tuned up easy. It sucks gas now though, guess that's a good thing if you're getting the power returns!
I can't speak to the longevity of the kit vs oem. From some of the veteran members I haven't heard any flack about the Baileys kit and my research found them to be reliable. The intake and exhaust ports had casting flash that I smoothed out before install, slight variance in squish of about .001-2. Overall it runs great, kicks over every time and tuned up easy. It sucks gas now though, guess that's a good thing if you're getting the power returns!
Haha yeah im sure it burns a tank like nothing else. Well cool im glad it worked out for you. I just checked ebay and found a meteor P&C with caber rings shipped for under 120. Pretty tempting considering the other option is dropping over 1200 for a new saw when mine works just fine.
