Any Stihl MS660/066 experts here?

ambo11, Sep 9, 2:31pm
I'm building a budget MS660 from farmertec for a mate, with a couple of old 066 for parts.
But having trouble with the plastic top cover, only have one from an 066. which seems to be the same as the MS660 takes?
But I have a gap at top of starter/bottom edge of top cover, which is big enough to let all the flywheel cooling out. obviously not prepared to run it like this.
Any ideas on cover? they "seem" to be all the same on the net?
Yes. I'm fitting it correctly. lol
cheers

desmodave, Sep 9, 3:18pm
You could spend another $15 odd to complete the Chinese rebuild with a new top cover or even cheaper if you deal direct with that parts maker . Keen to know how it holds up .

ambo11, Sep 9, 5:04pm
Cheers, they get a good rep overseas, advised to use 40:1, obviously not as good quality wise as genuine Stihl, but less than a quarter of the price.
I'm keen too, as I have an MS661 and this mS660 copy will be nearly 10cc bigger, but I'm sure the 661 will be a faster cutter. but the mate I'm building it for wants it for the experience and fun of it too. plus his spare money is currently going into his new home build.
Happy to get a new top cover but the one I have now off the 066 is a very poor fit. will recheck part numbers, and also the starter part numbers. seems strange.

two9s, Sep 9, 5:27pm
I run both of my big saws on 25/1. Manufacturers quote silly ratios to keep the greenies happy. But if you want longevity from a 2 stroke, crank up the oil ratio. Helps keep the saw cooler when working hard, especially if milling (like one of mine does from time to time. 1 fill of the tank for 10 foot of travel down the log! ) It also keeps everything lubed nicely. Spark plugs are cheap, compared to a rebuild of a top end.
But don't listen to me, I'm only running a 2 stroke for 39 years on the original piston and rings, I shitith you not:)

ambo11, Sep 9, 5:35pm
Yeah I agree with the 25:1 with milling, but with the modern synthetics 40:1 is safe for general use. Might be buried in a log for 2 minutes working hard, but then gets to cool down a little.
I have never used 50:1 at all, never will. but I think a spotless air filter, excellent tuning, and a sharp chain all help to protect the engine.
Mate I'm building this for has an 038 he bought new 13 years ago, run on whatever two stroke he had laying around, often marine two stroke at 50:1, never maintained. still a torquey beast with lots of compression. In fact he decided to replace the original plug last year.

serf407, Sep 9, 7:57pm
I know a little bit about the older small wallet emptying stihls.

The stihl 066 was made from 1988 to 2003, around 1995 a decompression button was added, so 6 or so years of 066 have buttonless top covers.
2004 066 parts lists shroud as 1122 080 1606 or 1607
http://oregonvyhne.sk/domains/7l8j90ep7a/my_files/Vkresy/Stihl_066_IPL.pdf ms 660 parts list has 122 980 1604 (which is the aftermarket parts version) https://www.motoculture-jean.fr/upload/pdf/MS660.pdf https://www.diyspareparts.com/parts/stihl/diagrams/ms660-magnum/

Know anyone handy with a small 3D plastics printer?
Saws sold into different markets can have different air filters, heated handles, different carbs, different handle designs etc.
You might be able to find early 066 parts list's in a microfiche archive (if you don't wish to ask the dealer)

snoopy221, Sep 9, 8:05pm
Tink if i recall correctly the ms starter cover is higher in that area-(presuming it is the elastostart)

recheck part numbers, and also the starter part numbers

richard112, Sep 9, 8:58pm
Have used 50-1 on Stihl & Echo now for lots of years. Never had an engine problem. Serious hard work. Not Alaskan mill, but solid. Recall some time ago being told not to increase the oil ratio into the mix as will increase the viscosity, cause the motor to run lean. ?

ambo11, Sep 29, 7:47am
Correct, the oil lubricates, the petrol cools. modern oils are unreal now but I still feel safer with the 40:1. saws need tuning to suit.