050 051 075 076 Info Thread

[JDNicol]

Seem to be a lot of purely opinion based threads about lately so I thought this might be good for a change.
I picked up an alleged 076 parts saw some weeks ago so I decided to do some research on the development/differences of the series. I have read nearly all the 050/051/075/076 threads I can find using the search function and Google, using keywords such as "075 trigger", "051 ignition" etc
I can tell you it makes one hell of a difference if someone has used an appropriate title.
I have a service manual (seems to have quite a few what i interpret to be ambiguous statements). I have been looking for 1978-1980 ipls for the 075/076 saws (which are my primary interest), there are some on ebay US but one of the sellers blocks international buyers from contact and the other I haven't heard back from. Tech update (27.1980) seems to be the "missing link" but again I have come up with nothing. :help:
From what I have read there seems to be one hell of a lot of heresay and contradiction surrounding the saws (quite a lot from Stihl themselves). In the past several AS members have testified that they have owned a 075 with a side oil cap but for the most part they have been ignored...
There are going to be quite a lot of pictures some of which I have borrowed from fellow AS members so I hope no one minds.

 

[JDNicol]

As per Stihl (poster of 051); The 050AV launched onto the market in 1968. Consistently upgraded. The increase in power combined with the installation of an electronic ignition system made it necessary to enlarge the air filter housing thus distinctively changing the machine's shape so that it was finally renamed in Stihl 051AV in 1972.

I believe the 050AV always had the ball bearing at the ignition side and the cylindrical roller bearing at the sprocket side.

So here is our first contradiction. The service manual says; "051 and 075 crankcases are identical (I assume they are not inluding the diameter of the cylinder mounting holes) on machine numbers 9280310 up to 9281309 and from machine number 9422350 onward. On earlier versions of the 051 the crankshaft is supported in a ball bearing at the ignition side and a cylindrical roller bearing at the sprocket side"
Also;
"Early 051 machines had a breaker controlled magneto ignition. As from machine No. 3001400 exclusive use is made of the breakerless (transistor) magneto ignition system."

The poster implied the electronic ignition went on the 050 BEFORE it was renamed????

Here is a picture of a crankcase with the roller bearing, note the two mounts in vertical alignment behind the flywheel to mount the breaker system.

Another;

A later version (breakerless), note the two mounts for the trigger plate, one has a protrusion.

The 075 never had points and AFAIK shared the same ignition as the 051 (without points).

 

[JDNicol]

Evolution of the 050/051 crankcase part numbers;
1111 020 2110 (1969) > 1111 020 2100 (1983)

The dates shown are the year in which it was last supplied from the factory as a spare NOT the year it was stopped being used on new models.

The latter i believe to be the NOS one shown above. It is worth noting crankcase part numbers are pretty useless as your crankcase will have two numbers (flywheel and clutch side), however, the IPL will only have one. I believe the 1111 020 2100 has crankcase half numbers 1111 020 2900 and 1111 021 0700.

Also;

1111 020 2101 (1983) > 1111 020 2102 (still available in UK)

So i would presume 1111 020 2101 belongs to the 051 case shown above with the top oil cap and breakerless mounts under the flywheel. The 1111 020 2102 has the side oil cap and is the recommended replacement now.

It is also worth noting Stihl quite often make changes to parts WITHOUT altering the part numbers. So there are bound to be more than 4 different crankcases for the 050/051. Some of which i have pictures of...

 

[JDNicol]

050/051 Coils;

1111 400 1300 (1974) TI (24.1974) > 1111 400 1305 (1990)

Same date system as before.

Seeing as there is a TI listed for 1974 I assume that 1111 400 1300 did actually stop being used in 1974. Which would fit with the release of the 075 saws in 74'. 075 only had electronic system.

A picture of a 1111 400 1300 coil;

1111 400 1305 (used on 075 also);

 

[JDNicol]

Flywheels;
not as easy to trace, ideally you always want the oldest part number you can find and then work forward. The fact some only have for example a bosch part number doesn't help either.
It is also possible the part changed but the number did not.

1111 404 1202 used on 051 electronic and 075 saws;

Earlier version with the windows, for adjusting the contact breaker gap;

From the service manual;
"On machines with a breaker controlled ignition system the flywheel is provided with apertures to facilitate setting of the contact breaker gap. These apertures are not necessary on electronic ignition systems. For this reason the cover plate was also deleted from machine No. 4622861"

The cover plate, part number 1111 195 5500 (i think);

 

[JDNicol]

This is where it starts to get interesting....

For now I am going to focus on the 075/076.
From the service manual;
"With the exception of the rewind starter and the ignition system, the new 076 and the 075 are identical. The relevant engineering changes are outlined in technical information bulletin 27.80."

AFAIAA the 076 always had the pawl system and the 075 always the morse fairbanks (friction). However, I believe they interchange, you would need to change the flywheel and depending what trigger you have, that also.

There appear to have been quite a few changes to the 076 crankcase over the years to accomodate different trigger units. I have checked some of this with Stihl USA, who have been very helpful (Stihl UK customer service...:bang. One of the technical advisors told me the 076 never had a trigger unit under the flywheel. However, I emailed again, hoping to clarify a few points. A different technician agreed with what I suspected that the early 076 saws had a donut shaped trigger unit under the flywheel. Both confirmed the late 075 saws had the oil cap on the side...

 

[JDNicol]

An early 076 trigger plate;

Notice how it is a full donut shape.

There are at least two 075/051 trigger plates;

Notice how both are 3/4 donut shape. The most imortant thing to notice is the two different size mounting holes. One of the holes corresponds to the protrusion on the crankcase, as noted earlier.

 

[JDNicol]

Trigger mount differences on 075/076.

This is the crankcase the early 076 trigger came off;

There is no tapped hole to mount the trigger unit below the AV mount. Also there is no protrusion on any of the mounts behind the flywheel, they are all flush.

A late 075 crankcase (all 051/075 electronic saws appear to have this configuration of trigger mounting);

The Stihl tech didn't know why there are 4 tapped holes under the flywheel for the 076, he said it was a possibility other countries installed a points with condensor system.

 

[thomas1]

I believe the 050AV always had the ball bearing at the ignition side and the cylindrical roller bearing at the ignition side.

If you're trying to keep everything straight you might want to edit the above. Unless both bearings are on the same side.:msp_wink:

 

[ptjeep]

Thanks for posting this info! I'm in the process of going through a 075 right now and am dealing with the trigger module now, i think its bad. Keep the info coming if you have more.

 

[JDNicol]

Developments in 076 crankcases

So early 076 = full donut trigger under flywheel. No tapped hole in AV mount for external trigger.

It is also worth noting the coil used with that early 076 trigger unit appears to be the 1111 400 1301;

This is the same coil to be used with the later AV mounted external trigger (1118 400 1001) (also used on 020av saws);

A tapped hole was added to the 076 crankcase but initially the 4 mounting holes under the flywheel remained;

Recognise the picture Brad?

The rest will have to wait untill tomorrow.

 

[JDNicol]

If you're trying to keep everything straight you might want to edit the above. Unless both bearings are on the same side.:msp_wink:

 

[JDNicol]

As shown before, later versions of the 076 had the tapped hole in the AV mount (which was beefed up accordingly). Whilst still maintaining the 4 mounts under the flywheel;

I believe later versions did away with both. However, the beefed up AV mount remained (just no tapped hole)...

At some point (before 91') the 051 shared it's crankcase with the TS510 and the 076 with the TS760.
The modern part numbers for the 051 crankcase is; 1111 020 2102 and 076; 1111 020 2116.
According to an IPL for the cut-off saws these number crankcases were used upto machine number X 23 531 439 (TS510) and upto X 23 529 742 (TS760). (27.1991)

Screw plug 0000 951 7102 was used to block the manual oiler hole.
Plug 4205 647 7001 was used to block the oil flow rate adjustment hole. Note both required a sealing ring, not included in above part numbers. I believe for the oil tank vent you could either use a plug (9302 929 0840) to block up the hole (on earlier versions I think) OR a grommet (4205 647 9100) to enable the use of the oil tank as a reserve fuel tank?

The reason I have brought the TS760, TS510 up is because I cannot find a picture of a more modern 076 case. It is possible the case continued to be developed after the 076 stopped production, however.

A TS760/076 crankcase;

Note the beefed up AV mount with no tapped hole and no mounts under the flywheel. For a 076 it would be set up to use the ignition module 1111 400 1303 i.e. no trigger plate.
TS760 saws used the module for a while but in 95' went back to using coil 1111 400 1301 with a different kind of trigger plate (not used on 076). It mounts between the AV mount, part number 4205 400 1001;

The "backward" step on the TS760 was done to make it rev limited via the ignition system instead of the control valve in the carb.

EDIT;
there are several of the between the AV mount triggers -1000 changed to - 1001 see TI (26.96). Also US/CAN apparently used different to Europe, -1001 used in Europe, -1002 in US/CAN.

 

[JDNicol]

Alright, so why do I think I am not just looking at 076 cases (i.e. not 075/051 cases with side oil caps)?
(Apart from what Stihl Technical told me)

An old 075 case (1111 020 2115);

I have posted a picture of an old 051 case above somewhere.

Note the position of the serial number.

The 075 and 051 saws were offered in a quickstop version.

Part number for 075AVEQ model plate; 1111 967 1501
Part number for 051AVEQ model plate; 1111 967 1500

The handle guard/brake mounts position themselves on the case right where the serial number used to be. Hence, the serial number had to be moved to accomodate the change.
However, the serial number can't be located to the other side of the crankcase (like the 076) if the 075AVEQ had a top oil cap, the cap would be in the way.
AFAIAA there have only ever been two positions for the serial number. Thus, the 075AVEQ had a side oil cap!!!

I am not saying the side oil cap was introduced on the Q models (in fact I think the side oil cap was slightly before), just that the Q models couldn't have had a top oil cap.

Also the service manual I have doesn't really deal with the 076 at all. It just makes a statement about the different ignition and recoil and doesn't really mention it again with any significance. Several pictures show a saw with a side oil cap and the friction recoil (which the 076 never had). A picture from the service manual where it states which model it is talking about;

 

[maico490]

Good stuff Jonathan
When the ignition died on my 056 this sort of thread was why I started following this site. However they take a lot of effort on the part of the poster so well done.

 

[Nardoo]

Great research sir. Gives me a little more confidence for when I pull my 051 down.

 

[atvhead]

thank you posting this info. when the time comes for me (my 051 will crap out again at some point) this will be very helpful.

 

[leeha]

Great thread, Alot of work goe's
into these types of threads.

Thanks for sharing


Lee

 

[JDNicol]

The 076 Super

IMO a bit of a gimmick. Kind of fits in with;

All 076 saws intended for sale in North America were the Super version. Those that you see that are not Supers were imported in the secondary market.

The Super didn't have any more displacement. The Super had the WS-26A whereas the 076AVE/Q the HS-60D (both rev limited via control valve). There are some other differences such as the higher intake block, holes in handle frame etc. However, regardless of what the IPL shows, I think some of the changes might be attributed to the date/age rather than the specific model.

Something I have not been able to find out;
did the labelled quickstop models have the isolating clutch?
All Super models were also quickstop models (please feel free to correct me). The 076AVEQ and 076AVSEQ model tags appear to have stopped being used in 1983 (up to serial number X 11 452 120, (25.1983)).
The round head rivets are also shown to stop being used at the same time. So I presume the 076AVE tag stopped also (it is shown with an asterix, meaning previous model but no tech references).

The decompression valve (1124 020 9400) is shown up to X 11 094 220, (25.1983). Hence, looks like some Supers won't have had it.

I was told by Stihl Technical the 076 manufacturing run ended in 1986.

 

[JDNicol]

I am suprised this thread hasn't attracted that much attention seing as it would suggest a lot of the info already on this site to be wrong concerning 075/076 differences.:dunno:

First to make clear some things I have mentioned;

There are at least two 075/051 trigger plates;

I should have said at least two different trigger units possible under the flywheel (051 went the way of the external trigger like the 076 eventually)

Additional info:
The flywheel with the windows on the 050/early 051 saws had part number 1111 400 1201.

I have quite a bit more on the 076 trigger plates but at the moment I am trying to see if serial numbers might be any good at identifying late 075 over 076. I have gone through all the modern (that is all i have) IPLs for the saws that were around in that era and collated the serial number vs tech reference data.