051 or 075?

hey fellas, need some help here. a while back i picked up what i thought was an 075 off of craigslist for a decent price. it needed a new muffler and i finally found one on ebay. got the new muffler swapped for the old and when i went to put the muffler cover back on.....the new muffler is about 1/2" wider than the old. contact the ebay seller to ask what's up and he says i've got an 051, as the 051s had the slimmer muffler. is he right?
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note the lack of manual oiler, although the hole is there and looks like a plug is installed. also, you can't see it in these pics, but there is a decomp valve to the right of the spark plug as you're looking at the rear of the saw. is there any sure fire way to tell these saws apart? i'm not mad, but i'd like to know what saw i've got.
any help is appreciated.

The 051 cylinder is held on the crankcase by 4 bolts through the base of the cylinder. The 075 will have studs that extend from the crankcase all the way through the entire length of the cylinder and the retaining bolts are right on the top of the cylinder. So pull the rear cylinder cover/lower handle mount off and if you see 4 bolts right on top it is the big boy, if you don't see them then it's the "little" guy.

i thought the 076's had the oil hole facing outward and the 075 had the oil hole facing up???or can the 075 have this to?

Listen to what Hoss is saying. The case is definitely not an 075--note the mount for a hand guard and the oiler fill on the side of the case. Also, it appears the recoil/fuel tank is in different condition than the case. That assembly is an 075. You have yourself a mutt. Check the studs and at least you'll know if you have the big dog. Hard to say with mufflers. I imagine any muffler off an 050, 051, 075, 076 and related chopsaws will bolt up. The shields are a different story.

Still, whatever it turns out to be, it still is in good shape.

Chris B.

Chris is right. The crankcase is likely 076. The starters were swapped around all the time. An 051 is not likely to even have the hole for the oiler. The mufflers however are a different story. There were narrow and wide mufflers for both the 051 and 076 the wide ones were called "high capacity". The exhaust ports in the 051 and 075/076 are not the same size and the mounting flange on an 051 muffler will not match up with the mounting holes in an 075/076 crankcase and vice versa. I have done a few 051 to 075 conversions and the muffler is one of the items you HAVE to change. Just check for the cylinder studs to tell the real story.

When I got my 76 it had these spacers. At first I thought they were an add on so I went to cheapsawstuff guy and he did not have a wide one either..

after a while I had been told by a few people that these spacers were put on at factory.

I think they had extra covers left over and it was an easy mod for them.

so, 1/2 spacers and longer bolts and off ya go.

thats my story and i'm sticking to it.

thanks guys for the info/expertise. i'll definitely pull er apart just to see for sure. although with hoss' experience (of the 051 muffler not even mounting) and sawbones' photo, i'd reckon that i've got an 075. sounds like stihl just made two styles of muffler (one narrow, one wider). i'll probably just do like sawbones' saw and add spacers. looks a bit goofy, but then so do i.

My 076 super has those same spacers.

so i pulled the rear handle cover and this is what i found.....
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so it looks like it has the studs that extend all the way thru the cylinder thus making it the 075. at least i think i'm reading that right based on what you guys are saying. correct me if i'm wrong, though!

yes sir it looks like an 075 to me for sure now , i kinda like the studs coming all the way thru the cylinder , makes it easy to install all the internals of the saw . im working on finishing one up now , waiting on ignition system, love the old saws tho , good find.

bump. can anyone else confirm that this is an 075 cylinder for me?
cheers
mb

Yup, that's a 111cc cylinder. Got a couple myself. These powerheads are notorious for shaking themselves apart. If I were you, I'd loctite those muffler bolts while you have it apart. My 075 also likes to throw off the recoil housing periodically. Most of those holes have been helicoiled in the past.

Chris B.

thanks for the confirmation fellas. i removed and loc tited every bolt i could last nite, so hopefully she'll stay together. i'm gonna use the wider muffler and just let it ride. thanks for all the help guys.
mb

oops looks like I'm a bit late here - I could have saved you that trouble pulling it down...

One sure way to tell be inspection without removing anything is to look at the decomp button/plug. If it's in the lefthand hole (nearest sparkplug) it's an 051, if it's in the RH or furthest from spark plug, it's an 076/075.

But you know this now so maybe someone else is armed for the future.