Stihl 076 rebuild......

Hi, first thread here from a newbie so go easy on me.:newbie:

Thanks to BobL for introducing me to an awesome site which I have already gleaned so much brilliant knowledge.

I am a Furniture maker/Cabinetmaker so am getting into chainsaws for the purpose of milling and getting free wood for furniutre.....(minus some blood, sweat and tears. )

As you can see from my avatar, I have made a portable mill and have been using it quite successfully with a cheapo electric Mcculloch until the clutch dropped its pants:help: ....hence I now have an 076 which is in need of some TLC.

I have a service manual (courtesy of Curt where I will also order my parts, Australian dealers are useless and expensive) and have pretty much stripped the saw and tested for compression (140psi cold) and have now got a parts list made up.

I also have lots of pics, but will start with just a few simple Q's.

Pic 1.

The fuel cap/vent. Is this in the correct order to go inside the cap? Any tips on getting it working properly?
I split apart the fuel tank to clean out and investigate and the gasket looked pretty poor. So when I reassembled it I used some gasket sealant. Filled the tank with fuel and it leaked like sieve. I don't know if it leaked before I split it apart, so not sure if I made some extra work for myself or not.
Got some new 0.4mm gasket paper and cut two new gaskets and used sealant between all surfaces. Eventually got a bone dry seal on the tank after a few tries and some head scratching.

Pic 2.

I am missing the idle screw and spring on the other side, but what is the purpose of this brass screw?


Look forward to some help from all the gurus here, cheers.

The big brass screw in the carb is the rev limiter. It dumps rich gas mix based on engine vibrations.

Here's a pic of the two fuel caps we mostly see over here. They differ from yours...

My 031AV has a cap similar to that. It has a valve (called a 'Tank Vent', PN 1114 350 5801) that looks similar to the two white pieces in the pic (but one large piece). There's a 'Threaded Pin' (PN 0000 951 5800) that goes between the valve and the cap body. It's larger diameter than the threaded post sticking out of one of the white pieces in the pic, and has a screwdriver slot on one end.

The PN for the whole fuel cap assembly is 1114 350 0501. Are these, or an updated replacement available for these saws? I hope so. Mine's still functional, but I found my vent rattling around in the tank the last time I opened it! I pressed it back into the cap, but have my doubts about it staying there with engine vibration...

Hi LS, thanks for the diagram. That is the same as in the manual I have, but the are no holes in the side of the cap, just the one hole in the top. Do you know of any new caps that will fit so I can upgrade it?
The saw will be mainly used on its side for milling, so I want it to work properly. Also, I believe its very important to have the correct/equal pressure in the tank for the carby to operate?

As for the rev limiter, should it be just screwed in tight? What is the purpose of it?

Eccentric said:

My 031AV has a cap similar to that. It has a valve (called a 'Tank Vent', PN 1114 350 5801) that looks similar to the two white pieces in the pic (but one large piece). There's a 'Threaded Pin' (PN 0000 951 5800) that goes between the valve and the cap body. It's larger diameter than the threaded post sticking out of one of the white pieces in the pic, and has a screwdriver slot on one end.

The PN for the whole fuel cap assembly is 1114 350 0501. Are these, or an updated replacement available for these saws? I hope so. Mine's still functional, but I found my vent rattling around in the tank the last time I opened it! I pressed it back into the cap, but have my doubts about it staying there with engine vibration...

Click to expand...

Yeah, thats where I found mine when I got the saw.....all the vent parts where rattling around the bottom off the tank.

Wonder if this one fits?
http://cgi.ebay.com/Stihl-new-style...ryZ79669QQrdZ1QQcmdZViewItem#ebayphotohosting

old school

Nope, need a screw in cap. I would look for a better used or a new cap. Remember, the vent in the cap must let air in the tank, or you will have a lean condition. Not something you want, especially when milling.

stihltech said:

Nope, need a screw in cap. I would look for a better used or a new cap. Remember, the vent in the cap must let air in the tank, or you will have a lean condition. Not something you want, especially when milling.

Click to expand...

OK, fair enough. I don't have a pressure tester but can suck and blow a little air through the cap so I assume it is working.

I got the saw running today and it seems to be working well. I cant tune it properly yet as it is missing the idle screw and spring.

What does it mean when revving the engine and it takes a little too long or slow to come back down to idle speed?

It usually mean you have an airleak.. check the carb bolts/nuts and gaskets..

martrix said:

As for the rev limiter, should it be just screwed in tight? What is the purpose of it?

Click to expand...

It stops the saw for over-reving.. Just screw it in tight. If you don't know how to tune "in the cut", just set your H screw 1 turn out from gently seated.

Lakeside53 said:

It usually mean you have an airleak.. check the carb bolts/nuts and gaskets..

Click to expand...

yeah, I guess that makes sense. Possibly means its getting some extra oxygen from a leak somewhere?

When I pulled the carb and the rubber boot off, I did notice the gasket was a bit tired, and from memory there may have even been a small section missing.
After playing with the fuel tank gasket, I know realize how crucial a good seal is.:bang:

I have a roll of 0.4mm gasket paper. Would a couple of layers of that with gasket sealant in between be sufficient? or do I need the thicker cork gasket?

hows that for a newbie question.

Just buy the gaskets.. they are cheap and available...

OK, pulled off the carb and I remembered correctly about some gasket missing..(see pic) This is the gasket that mates directly on to the cylinder flange.

Thanks for the help Lakeside, I will report back when I change the gasket. I'm not betting on my Stihl dealer having the right gasket but I will try them. I'm in Australia.
Everything else I have asked them for so far they haven't had....I will just get some thicker gasket material and make one if they don't have it. cheers.

That will do it..

OK, got the new gaskets made and installed. Seems to be better and I can actually get the saw to idle, even though it is missing the idle screw.

I cant get it to idle as low as it should, and it also seems to waver about a little in rpm's, but I guess I cant tune it properly until I have a working Idle screw?

Is it a bad idea to try and tune it without the chain on?

I have searched a fair bit both on google and here, but cannot find a good tuning guide. The madsens website is down.
Can anyone direct me to a good tuning site or post the Madsen's guide if they have it? cheers.

The Madsens guide will not help you - you saw carb has the limiter valve... and you'll end up with it way to lean if you try to do it by ear. I don't have the 076 manual in front of me, but I'll try to look it up tomorrow. For now just put both L and H screws 1 turn out.., and put the bar and chain on it for tuning...

BTW.. I assume you mean you are missing the LA screw, not the L screw... The carb won't work without the L screw..

Lakeside53 said:

The Madsens guide will not help you - you saw carb has the limiter valve... and you'll end up with it way to lean if you try to do it by ear. I don't have the 076 manual in front of me, but I'll try to look it up tomorrow. For now just put both L and H screws 1 turn out.., and put the bar and chain on it for tuning...

BTW.. I assume you mean you are missing the LA screw, not the L screw... The carb won't work without the L screw..

Click to expand...

Hi LS, yes both the H and L mixture screws with springs are there. The one missing is the Idle speed screw/spring, that attach's to the air filter and not on the actual carb.

The service manual says 1 turn for the H screw, and 1 1/4 turns for the L screw. I will just leave it at that for now.

If it is a little smoky does that mean its running rich? Also, should there be a slight oily residue forming on the vents of the muffler?

I ended up making an idle screw by grinding the tip into a taper like the original and cutting a spring to fit in between. Seems to work fine.

Next question is about the bar.

When does the tip need to be replaced? (see video)

I don't know if they play in it matters, as I assume its all under tension when the chain is on and is not an issue?

martrix said:

If it is a little smoky does that mean its running rich? Also, should there be a slight oily residue forming on the vents of the muffler?

Click to expand...

It will appear to "run" rich because of the carb limiter. "In-the-wood" the mixture will be correct. If you don't like the smoke, run it on full synthetic mix, 50:1.

martrix said:

I ended up making an idle screw by grinding the tip into a taper like the original and cutting a spring to fit in between. Seems to work fine.

Next question is about the bar.

When does the tip need to be replaced? (see video)

I don't know if they play in it matters, as I assume its all under tension when the chain is on and is not an issue?

Click to expand...

That's bad... Your rivits are lose or the holes in the bar/tip are slogged out. Try setting the rivits again (bash with hammer, anvil beneath). I wouldn't run like that.

Here are some pics of my piston/cylinder through the exhaust port. The is some scoring but it is not very deep. It is also hard so see any factory machined markings, so I guess it is well worn in?

I have done a compression test (cold) and is was consistently around 140-145psi.

I haven't tested the saw in the cut yet, so apart from the compression test, I don't really know how much power it has.

Lakeside53 said:

That's bad... Your rivits are lose or the holes in the bar/tip are slogged out. Try setting the rivits again (bash with hammer, anvil beneath). I wouldn't run like that.

Click to expand...

OK, I think in that case it is a bin job. I checked the guide rails and in some spots the gap is 2.1mm and it should be 1.65mm so that I believe is too much slop. Oh well, might be able to use the worn bar to make some hand-plane blades.

I am now converting the saw to 3/8" pitch and .063" gauge and ordering an new 36" solid nose bar.