Stihl 066 magnum red light help please

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Sammyp

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Hi all - apologies in advance for the long post, trying to outline everything needed with all information to get some solid answers.

picked up a not-running 066 (for too much - wanted a bigger saw to play round with and got excited...), previous owner took off exhaust to show me piston scoring etc, my thoughts at the time were that it was lean fueled or just rebuilt dodgily and could strip down and try again.

The only other info I had with the sale was that it had the 'upgraded' poly flywheel and M10 (flywheel side) crank and (yes I know, I know....) I didn't do enough research before buying it. I did look into the poly flywheel and better ignition etc. so thought I was a good idea it had been done.

I have since learned by reading on here that the larger crank cannot interchange into an older 066 due to the oil seal size change and overall width of crankcase. Please correct me if I've found a few posts that are not 100% fact?

I have now stripped it down trying to figure out what happened and have also been looking around this site and others trying to get more info on what bits this saw actually has in it. It has had a fair amount of metal flying around inside, crankcase is gouged (reasonably minor I think), rod has minor dent, cylinder is buggered (scored and intake/exhaust and ports all have been picked up by piston), plus dents all over the top as per photos, and piston itself is worn down on intake side from memory - you'll see on the photos below it's actually lost it's arris/bevel off one side of the piston!

At this point if I knew all parts were correct I would take the damage as a combination of lean fuel (bearings and crank are slightly blue - may well just be from the factory like that?) and more likely a dirty rebuild/exhaust carbon starting a chain reaction of destruction, with the operator not noticing the signs. the piston wear so severe on one side would still concern me though?

The problem I have is from what I read here and elsewhere the serial number on the crankcase is pre - upgraded crank spec 127 506 317 as per photo below, however I can definitely confirm that the crank itself has an M10 thread on the flywheel side (plus the flywheel is most definitely plastic!)

I've also measured the oil seal and it's 22mm od and 15mm id indicating that the case is actually the later version.

so... what do I have here? i'm thinking it's a bitsa? I am of 2 thought trains here:

1 - it's had the larger crankcase/crank upgrade and just a bad job of it

2 - it's had half a crankcase added to the existing other half (to suit oil seal) and stuck together. Is this even possible? and would this explain the entire thing destructing? I've read the cases are not as wide so thinking that a half/half scenario would maybe explain this.

I've taken photos of everything as below, if anyone can help out with identifying exactly what parts I've got here it would be greatly appreciated - would love to order some bits in and rebuild but want to make sure what I've got is compatible first.

thanks in advance - I can get more info/photos if needed.

Sam

IMG_2550.JPGIMG_2552.JPG IMG_2554.JPG IMG_2555.JPG IMG_2556.JPG IMG_2557.JPG IMG_2558.JPG IMG_2559.JPG IMG_2561.JPG
 
I see an aftermarket clip.
Are both intact ? (tangs still on them)
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The streaks look like water ingestion to me.
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I think what you're seeing is after somebody already tried to fix it.
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Looks like they forgot to bevel the port work perhaps? I can't tell much from the picture. Or something like a butterfly screw or something metal got ingested.
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Was there a case split gasket used, or was a sealer used instead?
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Aftermarket cylinder?
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The paint flakes and corrosion suggest it had been sitting a while in it's present condition before you cracked it open?
 
Think one half could be from an 064?

Need to get the serial run to be sure about that half at least.
 
Hopefully, these pics I took for a different thread should help you identify your crankcase.
Early Stihl crankcases didnt always line up well at all, and it could be an OEM replacement case (or case half) that was stamped with the original serial by the servicing dealer (that is normal).
These days individual halves are more uniform.
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thanks for info all, legends. I will go compare photos against what I've got and see how I go - out of interest, the flywheel side case half has a few indicators of model, is there anything other than the serial number level/angle on the clutch side that would give an idea? I'm 99% sure it's angled but my photos don't really show one way or the other, but it could be one of 2 different halves (it's definitely got the oval plug, i'm guessing the early 066 would not fit the larger crank?

do the part numbers vary from 064 to 066 for the case halves so I can check the clutch side? I thought they were the same but could be wrong? Also if the crankcases got wider with the introduction of the larger crank, does the part number vary in the 066's as well?ds

Alexcagle you mentioned aftermarket clip - sorry what do you mean by clip? and also there's not corrosion, I think you're just looking at scoring in the case half where the crank has dragged something round, pulled paint off and scratched into the housing.

Also all parts including the cylinder are genuine stihl other than maybe the piston - I can't find any markings on it so not sure on that. And crankcase gasket was used, I did check that based on previous experience!

Also has anyone got an IPL and service manual for these, looks like i'm going to need one!

thanks again
 
It's 066 both sides, has the angled serial no

Flywheel side 1122 021 0706

Clutch side 1122 020 2905

Clutch side older being 020 instead of 021?

Any thoughts appreciated
 
For Manuals, go to the Beg for manuals thread.
The clip I was referring too is a wrist pin clip. Those tangs are notorious for breaking off on aftermarket ones. The one in the pic is complete, but can't see the second one. The oem's are hookless.
 
Hopefully, these pics I took for a different thread should help you identify your crankcase.
Early Stihl crankcases didnt always line up well at all, and it could be an OEM replacement case (or case half) that was stamped with the original serial by the servicing dealer (that is normal).
These days individual halves are more uniform.
View attachment 547886

View attachment 547887


View attachment 547888


View attachment 547889

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@Definitive Dave This is a "saver post" for me. Thanks!
That's what AS is all about.
Did you make that?
 
ah, gotcha

yes they both were complete, one of them flew off somewhere in my shed when I pulled it out so I just left it there knowing piston was cactus anyway!

correct on Definitive Dave's post, very informative - hopefully he comes back to shed some light on my latest questions!
 
hi again,

sorry to drag this up but still not 100% sure what to do, can anyone confirm the crankcase numbers above for me? I've got the IPL (thanks Ray) but it doesn't give me the actual case number unless i'm misreading it? it gives you the part number for the whole lot, not just the case itself?

or, can I just buy a copy crankcase which will be the new version, and will everything bolt up to it? then I assume i'm guaranteed a fit for the current crank?

any help appreciated

thanks
 
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