MS 660 rebuild advice

[Mad Professor]

from Madsen's

 

[Fnkfab]

from Madsen's

This is a great document and with links to sounds!

I've been quiet waiting for parts. It seems to take my dealer about 1.5 weeks to get parts in. And this time they only ordered me one of the two o-rings i asked for (oil pump control screw), and didn't let me know that the control bolt was back ordered for the foreseeable future. I had heard good things about this place but haven't got a warm and fuzzy any any point during this rebuild. They didn't seem interested in my rebuild at all including when i brought it in stripped down. I asked for a tech to look at that cylinder-- and he did-- but he said there was no OEM tool for putting the circlips in for the piston/cylinder-- and we know this is true. He looked at the P/C and said it should be replaced "well if you're this far you should just replace it" I'm sure it's not all bad- but they seem more keen in selling new hardware then helping a little guy like me keep his stuff running. Sorta been a bummer.

Gonna sip my coffee and stare at the parts for a bit. Then probably call the other 6 stihl dealers that are within 25 mi of me and see if anyone has a damn o-ring and control bolt.

 

[BuckthornBonnie]

Many so-called “techs” don’t get much further into two cycles than replacing lines and checking the basics. Shop rates reduce how often they fully rebuild saws unless they’re into them themselves and enjoy the process.
It’s tough to find a good shop who can hang onto good mechanics. The turnover at one of my shops has been bad for the last six years or so.

 

[Fnkfab]

Went through my kitted parts today-- they actually only ordered me one of the o-rings. I guess my fault for not double checking the slip, but damn. I mean I handed them a piece of paper with part numbers and quantities on it.
Looks like the o-rings are 8mm OD, 4mm ID, 2mm thick, high durometer. Ordered a pack off mcmmaster that seemed a good equivalent-- should have those monday.

I confirmed that my existing piston is not the high flow -- easy to see from the ramps on the piston where it meets the control bolt. I'm not sure what to do about the control bolt. I just just grind the stop down like in the post i linked above. I also was able to find a 1128-647-4803 (MS460 high flow oiler bolt) that seems equivalent. I'll play around when i'm putting it together to see what makes sense.

Not being able to get parts for 2+ weeks from stihl has def slowed me down a bit.Hopefully have more soon

 

[Fnkfab]

Some mild progress--
I ended up just replacing the pump orings, plug, and seals and putting it back together. Big big improvement but still dripping oil. When I open the throttle, it drips out the bottom of the saw. The leak is still on the high pressure side, so less worried about pickup body side. Maybe its not seating right against the seal in the case, the o-rings aren't seated right, or maybe the original piston (that i didn't replace) is leaking. I'm thinking I'll try to order a control bolt again (it was indefinitely backordered) some new o-rings, and try again whenever parts come in. For now, i ordered an AM oil pump for 30 bucks. I'll drop that in and see how things shape up. truthfully, one thing i've gained from this project is just learning how the darn things comes apart and goes together-- now replacing components doesn't seem to take that long. If you guys have other suggestions for the oil pump, i'm happy to hear them.

In other news, i have the saw up running again with the dual port, max flow, and a tach. Hoping to get some time to tune it today at lunch or this weekend. Its louder-- throttle response faster, and hits 13000 RPM before WOT (like duh right) -kinda cool for a guy like me to see the difference though.

Ill report back on the tuning.

 

[Fnkfab]

Woof-- haven't posted much on here in a bit.
Saw is back together and i've run a few tanks of gas through it. Feels like about 30-50% more power than before tearing down. It's interesting-- it feels like more power and like the chain actually stays sharp longer. Maybe there's a compound effect.

I ended up rebuilding that oiler, replacing the gaskets, and it still leaked. I dropped a cheapo AM high flow oiler on there and that seemed a bit better. I'd re-used my old piston since it was hard to get new ones-- maybe i'll try rebuilding it again once parts are off back order.

Tuning was interesting. I used the tach and followed the instructions above (and then again went back to the manual). I have it at ~3000 RPM on idle and 12500-13000 on WOT, not in a log. I have noticed the saw seems to be tough to start for the first time of the day. It takes a lot more pulls to get the first fire up than before tearing down. That said, once it runs for a few minutes, it fires back up on the first pull for the rest of the day-- so i dunno what that's about. Maybe the carb needs some love in the near future? Mounting the tach was funny. I screwed it on-- and it snapped off. I double stickied it on and it fell off. I then just went with sticky velco and that seems to work just fine. A little surprising there.

Regarding RPMs-- some observations.

1. In the mill laying flat on its side, idles at 3000 +/- 200 RPM.
2. when milling, ~ 10,000 for most cuts the way I've been running it.
3. If i flip it over (handle up, flat on the ground the way you would usually set a saw down)- the idle walks up to 4000 RPM.

I have one other issue with this saw worth mentioning. I'm running a 36" stihl rollamatic ES bar on this. The bar saws 114" link-- but i could never get 114" chain to go on this. The slot doesn't seem big enough to let you get enough slack to put it on the 7T sprocket. Did stihl change their bars since the ms660? My solution has been to run 115", with the tensioner bottomed out and letting the bar come down a little to snug it before tightening up. I've thought about just putting the bar up on the milling machine (bridgeport type not saw mill) and lengthening the slot a little bit.

 

[BuckthornBonnie]

Yes to the carb possibly needing attention if you didn’t rebuild. Most 1122s idle close to 2500-2800 for me, but those are just numbers. The hard starting could be a lot of things so it’s hard to say from afar.

 

[Fnkfab]

Yes to the carb possibly needing attention if you didn’t rebuild. Most 1122s idle close to 2500-2800 for me, but those are just numbers. The hard starting could be a lot of things so it’s hard to say from afar.

Since the saw was happy starting before i tore it down and it seems pretty happy to run, i'm wondering if it could be a priming issue pulling fuel up out of the tank. The other thing that occurs to me is that messing with the tune could probably make it hard to start right? Maybe I should cheat my tune in one direction or another on the low end?

 

[Fnkfab]

Tuning was interesting. I used the tach and followed the instructions above (and then again went back to the manual). I have it at ~3000 RPM on idle and 12500-13000 on WOT, not in a log. I have noticed the saw seems to be tough to start for the first time of the day. It takes a lot more pulls to get the first fire up than before tearing down. That said, once it runs for a few minutes, it fires back up on the first pull for the rest of the day-- so i dunno what that's about. Maybe the carb needs some love in the near future? M

Revisiting this saw. It sat for most of the winter and wouldnt start a couple weeks ago at all. I rebuilt the carb (gaskets, screens, cleaned etc) from an oem rebuild kit. Put back on-- still nothing. Saw will fire a few times on ether. Clearly seems like a fuel delivery issue. I noticed that the impulse line wasn't quite on all the way-- and on further inspection, i'd pinched the white wire with the carb, so i probably didn't have a good seal from the cylinder to the carb. Just buttoned it back up again-- will be a few days before i can try to start it again-- tear some muscles in my shoulder yesterday.

So the question-- does this look right? The impulse line isn't bottomed against the elbow, but all the barbs are contained within the line.
I am regretting not replacing the impulse line when i had the saw apart.

 

[Woodslasher]

Looks fine to me, but the only time I've touched an 066 is to run one or fix the recoil on it.

 

[L34]

Pretty sure mine are like that

 

[Fnkfab]

So today's update- still wouldnt start. Ended up swapping the carb with a new in box one i had. Then it dawned on me that the saws been sitting for a few months. The fuel is ethanol free, but it just seemed like a good idea to empty and replace.. After those two things, and a few pulls, it primed and idled for a bit. Of course-- the pull cord snapped on me on the next start attempt and its too frayed to repair. I have a new bushing on order for it. I'll prob pick up some extra pull cord later today-- enough to plan on replacing it a few times and get this thing tuned up. Things are shaping up.

 

[Fnkfab]

Annnnnd we're good. New pull cord and she started right up. No adjustments other than the idle screw, and she's at 3200 RPM laying her on side idling and WOT gets to 12500. Hoping to get some time to play this weekend bucking up some trees with the 28" bar. Getting ready to do some milling in coming weeks.

I did peak over at some of the new saws they've sold some 661s, 881s, and 500is. Neat stuff. Not sure how I feel about the electronics part. Gonna try to run this for a few jobs this year and see where it takes me.