Picked up an 066 magnum the other day and had to replace the piston/rings. I bought an OEM piston that came with a good cylinder to do the job. The cylinder that came with the piston was a Mahle. The original cylinder that was on the saw just had Stihl cast into the base, along with the part number. Genuine OEM stuff I would say and appeared to have never been apart. Both appeared identical in every other way. I glass beaded both and just decided to put the Mahle cylinder back on the saw, since it came with the piston anyway and keep the Stihl one for a spare for another rebuild, if I came across one. Both are in excellent shape, with no damage or scoring. Well, I put it back together and had put the flywheel back on and went to hand spin the crankshaft with the flywheel, just to make sure all was well, and it stopped dead at the top of the stroke...had to step back a minute and think if I'd screwed something up. No, nothing was wrong, so I cycled it slowly both ways and when it would come to the top of the stroke, it would stop dead. The piston was obviously touching the combustion chamber. Took it back off and got a digital mic and measured the depth of both. The Stihl cylinder has about a 2mm longer bore than the Mahle. Put the Stihl one back on it and everything back together and all is fine. Here's my question: Can somebody here please tell me definitively if there is a displacement difference in the early 066 saws that are marked as Magnums? This one has a poly flywheel and the carb cover has the hump. I saw another post here that said there is a difference, that the Magnums (in the 066 line) were actually 98cc's or something like that, as opposed to 92. Is this correct? It would seem so, in view of the above. Then yet another post that said the Magnum designation was just a sticker and made no difference - only marketing. Don't know how much a couple of mm's would make in displacement, but it would obviously make some, with a longer stroke. (Just occurred to me too, that the connecting rod would also be a corresponding bit longer?) I also saw another post on here that said that if it had a factory dual port muffler, then it would be the larger displacement of the two. This one does not have a DP muffler. So I'm baffled and can't seem to find what I would deem as a reliable answer. At this point, it's more of a curiosity thing than anything else. But I sure would have hated to have had the original cylinder messed up and have gotten one that wouldn't work with the piston I bought. Might also help somebody else down the line to be wary of the difference. I was just fortunate enough to have the two good cylinders in my hands. Sure would appreciate if one of the real experts on here would enlighten me...I certainly am not one. Thanks to anybody who can shed some light on it...
066 vs. 066 Magnum - is there a displacement difference?
- Thread starter drsamm
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No. Same saw. TLTR, lol.
old-cat
Fir Man
NEVER put a saw together without measuring squish gap. Unless it's a clam shell thing.
splitpost
Nothing but 32:1
Shouldn't make any difference if its a clamshell,still should check it before final assembly
No, the Mahle had no gasket with it, just used one of the original thickness that was on the saw. The thickness of the original gasket was .5mm. Doesn't seem to me that a 1mm thick gasket would have cured this problem and nothing else was amiss...?
Could very well be. Perhaps the base was cut for a pop-up piston.
FIFY. I like your avatar. Your wall of text, not so much. I will now re-read your query.
My wall of text is like what you see in the avatar...lots of attention to detail. Like to be specific and clear. See a lot of posts on here with only 4 or 5 lines that I have to read a half a dozen times to just get a basic understanding of what's being said or asked...
I like all the words, it's the lack of paragraphs I was commenting on.
As for the Mahle being machined...I guess anything is possible, but it certainly doesn't appear to have been molested in any way. It is absolutely identical in every other way to the other one and of course, has the 54mm bore, so it's obviously not from another size saw. The saw is completely back together now, so I'm not going to take it back apart to further investigate. I've taken all different sizes of Stihls down to nothing and put them back together again, just never ran into anything like this with any of them. There are just so many of you on the site that know far more than I do about this stuff, I thought somebody would know at a glance what was up with this...
Ah, 10-4 on the paragraphs...no offense taken or intended. And you are right, in review, it does look a bit like some busy wallpaper. Was just so intent on getting all of the details in there, mixed with some frustration. Sorry for that. Anyway, will break it up right next time. I seldom post, just like to read all the others. Learn a little bit more every time...did you have a theory on the question? If it's something I did wrong or didn't notice, I sure can't figure it out.
I know absolutely nothing about these saws, firsthand. I cannot find, through internet research, any difference in stroke in any of the 064, 066, 660 models.
If it's not a modified jug, or a defect, it's a mystery to me.
Wish I could help.
If it's not a modified jug, or a defect, it's a mystery to me.
Wish I could help.
Deets066
Firewood hack
You could take two 066 saws and check squish on them and I would almost guarantee that they would be different.
Just from different info on here in the past and from my own experience. For example some people with a stock 066 can run without a base gasket, mine was 0.018" with the gasket, unable to remove.
Nothing unusual in your situation, put it together with what works and run it!
Just from different info on here in the past and from my own experience. For example some people with a stock 066 can run without a base gasket, mine was 0.018" with the gasket, unable to remove.
Nothing unusual in your situation, put it together with what works and run it!
10-4 on the put it together and run it... Just exactly what I'm going to do! I'm not the worry wart type to let it keep me from using the saw, just was really curious. I've seen several posts that claim different displacements and never knew if it was fact or fiction. Thought I had answered that question with these two cylinders. I'll just put the Mahle on the shelf until I can find another 066 to fix up and see what happens then. Thanks to all who answered! Some good theories put out...
And to dl5205 - thanks for busting me up on the long windedness of my post! I went back and re-read it and got tired myself. I do tend to get down to the tiny facts of things like this. My wife says the same too...and by the way, thank you for liking my avatar. It's 514 inches of FORD with a forest of Italian Webers on top. WIth a 90" wheelbase and about 2700 lbs, it's a fun go kart, just uses a tad too much gas to get out regularly! Might be why I like big screaming two stroke saws...
And to dl5205 - thanks for busting me up on the long windedness of my post! I went back and re-read it and got tired myself. I do tend to get down to the tiny facts of things like this. My wife says the same too...and by the way, thank you for liking my avatar. It's 514 inches of FORD with a forest of Italian Webers on top. WIth a 90" wheelbase and about 2700 lbs, it's a fun go kart, just uses a tad too much gas to get out regularly! Might be why I like big screaming two stroke saws...
Yep, Cobra. Aluminum heads, iron block. Got a buddy who has one but his block is aluminum too. Lots and lots of $$$$$ for that. Love to have one and lots of bragging rights with it but I really doubt it makes that much difference when you are making the kind of power these things do. Looks cool too though...
