# 076 AV Carb Settings



## cgarman (Sep 14, 2010)

I bought my 076 AV in the Spring, and I'm still trying to get it up and running on the mill. I ran across the thread about the special rim sprocket that has notches for the oiler (thanks guys) and just bought one. While waiting for it to show up, I decided to see if I could get it to run with no chain on.

When I first got the saw, it ran horribly, bogging down quickly. I put in a new plug, new air filter, and fresh gas with 50:1 full synthetic mix. It seemed to run better, but I didn't try any cutting because I knew about the misalignment issue with the sprocket and oiler.

Last weekend, I tried to fire it up, and I had an awful time getting it to fire up. The only way I could get it to start was to lock the throttle. After firing up, is seemed to increase in speed steadily for a few seconds. When I unlocked the throttle, to let it idle, it choked out.

I tried increasing the idle, and set it too high to where I couldn't shut it off (switch isn't working, but that's another story.) I thought about just running in the house while the saw ran out of gas, but I realized I could pull the plug wire, which I did.

Now, I THINK the idle is fixed, but the saw still runs rough and chokes out after a few seconds. I set the carb to the Stihl factory settings (1 turn and 1.25 turns out - I forget which H/L) but that didn't do it.

Would you guys suspect a carb tuning problem, or something else? Maybe some critter living in my muffler port? Bad gas? Bad mix? Bad luck? Any tips on how to narrow it down?


Thanks everybody. Sometimes this site helps me retain my sanity.


----------



## BobL (Sep 14, 2010)

cgarman said:


> I bought my 076 AV in the Spring, and I'm still trying to get it up and running on the mill. I ran across the thread about the special rim sprocket that has notches for the oiler (thanks guys) and just bought one. While waiting for it to show up, I decided to see if I could get it to run with no chain on.



No CS should be run without the B&C, and to try and tune it (especially adjusting the H screw) without the B&C is asking for trouble. 



> Last weekend, I tried to fire it up, and I had an awful time getting it to fire up. The only way I could get it to start was to lock the throttle. After firing up, is seemed to increase in speed steadily for a few seconds. When I unlocked the throttle, to let it idle, it choked out.
> 
> I tried increasing the idle, and set it too high to where I couldn't shut it off (switch isn't working, but that's another story.) I thought about just running in the house while the saw ran out of gas, but I realized I could pull the plug wire, which I did.
> 
> ...



I would recommend the following in this order
1) Fix the kill switch
2) perform a vacuum leak test and then do whatever flows from that
3) Clean the carby and if that fails try a carby kit.

But don't run the saw until you put a B&C on it. Make sure you are using freshly mix made with gas fresh from a gas station


----------



## BobL (Sep 14, 2010)

mtngun said:


> Doesn't logosol offer an electric power option for one of their CSM's ?
> 
> Why pay $300 for a router when you can get a used or surplus 5hp 3PH motor for less than that ? Power it with a vectorless inverter from 1PH 240V. It should do the job.
> 
> ...



I think this is in the wrong thread but . . . . 
Routers RPMs are not a problem as they are normally 8k to 25k rpm - but they have stuff all torque at those RPM.


----------



## cgarman (Sep 15, 2010)

BobL said:


> No CS should be run without the B&C, and to try and tune it (especially adjusting the H screw) without the B&C is asking for trouble.



Understood - I didn't want to 'run' it without the B&C, I just tried to start it and let it idle to see if it was the sprocket/oiler problem that was causing the bogging. I definitely didn't try to tune the carb with this setup, but did take it back to factory settings.




BobL said:


> I would recommend the following in this order
> 1) Fix the kill switch
> 2) perform a vacuum leak test and then do whatever flows from that
> 3) Clean the carby and if that fails try a carby kit.
> ...


----------



## BobL (Sep 15, 2010)

> 1 - does the kill switch ground the spark or disconnect it on the 076


Neither, there should be two wires coming from the coil - the kill action of the switch connects those two wires.



> 3 - The carb "looks" clean viewed through the top when the filter is off. What should I look for? How do I clean it - just a good spray carb cleaner, or do I need to take it apart?



Looking clean means very little - it has to be carefully taken apart and Washed in fresh gas, look for tiny (grain of sand or smaller) bits of watery fluff - gunk - corrosion etc.
Test all tubing and diaphragms have no cracks etc. 
If your eyes are like mine I suggest even using a magnifiying glass

But before you start it I do recommend a pressure test.

It really sounds like you need a service manual.


----------



## cgarman (Sep 15, 2010)

Agreed - I got the user's manual for free from Stihl, but could use a IPL or service manual desperately. Any idea where I can find one for this older saw?


----------



## BlueRider (Sep 15, 2010)

Go to this site and download the sevice manual for the HS series carb. 

http://www.tillotson.ie/techinfo-downloads.php

This will give you some good info on how to tune the carb as well as an IPL for the carb. the first thing I would do is to clean the filter screen inside the carb. The second thing I would do is to clean the valve seat inside the carb. these are notorious for getting varnish build up and then a bit of varnish wil chip off. from then on it is nearly imposable to get the saw to idle correctly. To clean the valve seat pull the plunger out and then hone the seat. I use a paper shaft from a q-tip. I cut the cotton part off and then use a razor blade to sharpen the shaft of the q-tip to a point like a pencil. dip this is a bit of three in one oil and then using a bit of pressure rotate it in the valve seat. It should soften a bit and conform to the seat and the Kaolin in the cardboard shaft will act as a very fine abrasive and hone the valve seat. This works extreamly well.

You may or may not be able to reuse the old gaskets to put the carb back together. a rebuild kit is about $25 from a stihl dealer or about $8 from your local tilotson distributer(follow the link from their web site)

I have not had any problems starting my saws without a bar and chain. But I have always done it with the rim sprocket and clutch installed. You can adjust the idle just fine this way as well as the low mixture screw. but to properly adjust the high mixture screw the bar and chain need to be installed so it can be adjusted while cutting.

Bob may be mixing his saws up regarding the kill switch. On my 051 and 075 there is only one wire going to the kill switch and for it to work properly the airfilter box must be grounded to the case via the ground strap near the handle. The ground strap is a ridgid piece of metal that is bolted to the filter box and uses one of the gas tank mounting screws to bolt it to the case.


----------



## BobL (Sep 15, 2010)

BlueRider said:


> Go to this site and download the sevice manual for the HS series carb.
> 
> http://www.tillotson.ie/techinfo-downloads.php
> 
> This will give you some good info on how to tune the carb as well as an IPL for the carb. the first thing I would do is to clean the filter screen inside the carb. The second thing I would do is to clean the valve seat inside the carb. these are notorious for getting varnish build up and then a bit of varnish wil chip off. from then on it is nearly imposable to get the saw to idle correctly. To clean the valve seat pull the plunger out and then hone the seat. I use a paper shaft from a q-tip. I cut the cotton part off and then use a razor blade to sharpen the shaft of the q-tip to a point like a pencil. dip this is a bit of three in one oil and then using a bit of pressure rotate it in the valve seat. It should soften a bit and conform to the seat and the Kaolin in the cardboard shaft will act as a very fine abrasive and hone the valve seat. This works extreamly well.



Thanks for the lead and the great description (except most of our Q tip shafts are made of plastic) 



> Bob may be mixing his saws up regarding the kill switch. On my 051 and 075 there is only one wire going to the kill switch and for it to work properly the airfilter box must be grounded to the case via the ground strap near the handle. The ground strap is a ridgid piece of metal that is bolted to the filter box and uses one of the gas tank mounting screws to bolt it to the case.


Yep - getting it confused with the plastic bodied saws which have two wires.


----------



## BlueRider (Sep 16, 2010)

BobL said:


> Thanks for the lead and the great description (except most of our Q tip shafts are made of plastic)
> 
> I'm not a loyal customer or anything but Johnson & Johnson brand q-tips are what I use. I used to use ones with wood shafts and I would cut them in half and chuck them up in my dremel to polish hard to reach areas. Talk about endagered species, try finding wood shafted q-tips.
> 
> Yep - getting it confused with the plastic bodied saws which have two wires.



I have one of those too and figured that was the case. I know you have a more sensible home electrical system but didn't think your imported chinsaws would be different.


----------



## cgarman (Sep 26, 2010)

*Progress...*

First off, thanks to BlueRider, who hit it on the head in several cases. The problem with the switch is a missing screw that connects the strap to the gas tank. Didn't notice that until I pulled the air filter box. That brings me to stage 2...

I downloaded the Tillotson manual, and against my better judgement, took the carb apart until I had a pile of screws. I sprayed WD-40 everywhere, scrubbed it with sharpened q-tips in the appropriate places, and put it back together with no extra parts.

4 pulls of the rope produced a blue cloud of smoke that was part WD-40 burning off, and part pure evil leaving my saw for good. I reset the carb to factory settings, backed the L screw out a 1/4 turn to help the low end, and increased the idle setting on the throttle to keep it running out of the cut.

Thanks to you guys, the old girl now runs like a striped-ass ape. I ripped at about 2 sqft per minute, with a partially sharpened chain.

Going back out today to touch up the chain and make more sawdust at the expense of my neighbors' patience. Can't wait to see what happens when I have someone else help me push.

Thanks again - you saved me tons of frustration. That was the kick in the pants I needed to tear it down and really find the problem.


----------



## DaltonPaull (Sep 26, 2010)

Glad you got the 075 running. When I got mine two years ago it was in a similar state to yours but bluerider pointed me towards the carb manual and since cleaning the carb it's been incredibly reliable, almost always starting within a few pulls when cold.

The only issues I've had are erratic running, caused by loose cylinder bolts, low compression, caused by de-comp unscrewing, broken starter spring and seized oiler caused by G-oil brand veggie bar oil (which also seized the oiler in my 066.)

I guess that's starting to sound like a long list but I've cut over 5000bF with it so the repairs have been pretty few and far between.

Have fun milling!


----------



## BlueRider (Sep 28, 2010)

Glad that link helped you guys out. The first few times I pulled apart the carbs on my saws I did it by the seat of my pants an illustrated parts list leaves no gues work to which way the diaphram goes DAMHIKT. I found that site while looking for a better price on rebuild kits since I have two saws with the same carb and a spare carb. That would have been over $75 in carb kits from my local dealer. By ordering directly from the distributer listed on the tilotson site I spent about half that including shipping.


----------

