Stihl Contra Info Sharing Thread

[Steffen]

Some of you most have adjustet the timing on your Contra/Lightning, i know some of you think this is an easy fix. But i have not done this before and i would like to get this right.
Is there a guide or can someone tell me in low tech how this is done the right way??

 

[omega_supreme]

When I put mine back together I have been pondering how to set the timing correct again as well (the difficulty being that the spark plug hole is at an angle). After a lot of reading I used the following proceedings.

Screw something longer than the spark plug (I used part of my timing dial gauge for the 090) in the cylinder so the piston cannot reach TDC. Turn the engine in an arbitrary direction (say clockwise) until it stops. Now take a pencil and mark both the flywheel and casing. Turn the engine the other way (counter clockwise) until it stops again. Mark the casing where the mark on the flywheel is at. The TDC is now in between the two casing marks.

I believe the points should be opened 0.4mm at TDC and 3mm before TDC they should start to open. I use a common multimeter to measure the difference in resistance between opened and closed points. To find the 3mm before TDC was kind of tricky (you'll need something exactly 3mm that fits through the exhaust port to hold against the piston). In the end that turned out to be 30 degree before TDC, which is not uncommon. So I took a degree wheel en adjusted the armature (some trial and error involved) until I could measure a different resistance exactly 30 degree before TDC. The caveat here is that I have not tried the saw so I cannot say for sure the setting are perfect. It worked for the 090 though and the only difference is that I could use a timing dial to find TDC there.

Perhaps you may find this method useful.

 

[Steffen]

Thanks for your help. Its worth a shoot, its the best way at the moment. But Stihl most have made a way to do this. What was the way to go back in the 60s, the workshops most have had a working manual to work from??

 

[omega_supreme]

I'm also pretty sure this is not the way Stihl had intended. If you check post #522 from this thread, you'll see that member pioneer saws has a service shop manual for the Contra-Lightning. It's the only one I know of but at the time he had not scanned it. You could ask him to check if that manual has anything to say about resetting the timing.

 

[Eddy_t]

Well, what tool did you use? The sparkplug hole is not at the top of the cylinder its from the side, Its not possible to measure the TDC from that i think.

I used a plastic piston stop, and set the points by watching it bob up and down, guessing! I've probably set the timing a bit earlier than 3mm


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[pioneer saws]

I'm also pretty sure this is not the way Stihl had intended. If you check post #522 from this thread, you'll see that member pioneer saws has a service shop manual for the Contra-Lightning. It's the only one I know of but at the time he had not scanned it. You could ask him to check if that manual has anything to say about resetting the timing.

Ive still got the Contra manual, got it from an old friend who was the first Stihl dealer in this area.
Still haven't scanned it, at work at the moment so will dig it out tomorrow and have a look see.
Justin

 

[Steffen]

I have been out testing my "hybrid" Contra S in some firewood. Its one big powerhouse... It runs better than the normal Contra S and also better than the 090. I have been told that S cylinder has bigger transfar ports than the 090 cylinder, and the 090 piston has bigger windows than the S piston. Therefore the mix with the S cylinder and the 090 piston works better than the original setup. I have not looked much at the transfar ports before i put this saw together, maybe some of you guys that has the cylinders for spares can test this?? But i can tell you this saw runs great.

You can se it here:


I have found an original Contra/Lightning service shop manual from dec. 63. Do any of you have one that is later or older than this one? Also im looking for some bulletins for the Contra, please let me know if any of you have some.

 

[Eddy_t]

I have been out testing my "hybrid" Contra S in some firewood. Its one big powerhouse... It runs better than the normal Contra S and also better than the 090. I have been told that S cylinder has bigger transfar ports than the 090 cylinder, and the 090 piston has bigger windows than the S piston. Therefore the mix with the S cylinder and the 090 piston works better than the original setup. I have not looked much at the transfar ports before i put this saw together, maybe some of you guys that has the cylinders for spares can test this?? But i can tell you this saw runs great.

You can se it here:


I have found an original Contra/Lightning service shop manual from dec. 63. Do any of you have one that is later or older than this one? Also im looking for some bulletins for the Contra, please let me know if any of you have some.
View attachment 421118 View attachment 421120

Interesting, I hadn't given thought to different transfers (I'd assumed they were the same), but that would explain the increase of power. I wonder how much different the porting is? Have you used a paper or liquid gasket on the cylinder?


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[Steffen]

Interesting, I hadn't given thought to different transfers (I'd assumed they were the same), but that would explain the increase of power. I wonder how much different the porting is? Have you used a paper or liquid gasket on the cylinder?


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I use the original gasket again with some liquid on top of it. I was thinking about removeing it and only use the liquid. But dont know if there is room for the piston in the top of the cylinder. I did a compressiontest after a few runs. It has 150pis. My 090GS has 175psi. But my "hybrid" Contra S seems to run much better.

 

[Eddy_t]

I use the original gasket again with some liquid on top of it. I was thinking about removeing it and only use the liquid. But dont know if there is room for the piston in the top of the cylinder. I did a compressiontest after a few runs. It has 150pis. My 090GS has 175psi. But my "hybrid" Contra S seems to run much better.

The easiest way to check is to remove the gasket and turn it over slowly to see if it contacts the cylinder head, if you're still unsure, the squish can be checked with a length of twisted solder.
Although 150psi is very high for a 100+cc saw, I bet the 090GS is a pig to start! My contra was only 100psi


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[Steffen]

The easiest way to check is to remove the gasket and turn it over slowly to see if it contacts the cylinder head, if you're still unsure, the squish can be checked with a length of twisted solder.
Although 150psi is very high for a 100+cc saw, I bet the 090GS is a pig to start! My contra was only 100psi


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I will try that one day, or if i find an S cylinder again. I will build one more, and make some experiements with that. Dont anyone have a spare they dont use?? ;-)

But the saw runs great now, i would be sad to take it apart again. I have just made a 90cm 880 bar fit the saw with a new Stihl chain. This will be a great working saw for bigger logs!

Yes the 090GS is a tough one to start. I can only start it when i put some gas down the carb and pull one hard pull. If i try to use the choke and start it the normal way, it gets a little bit of gas in and pulls the starter out off my hand...

 

[Steffen]

I have found a supplement for the Stihl manual from November 1959, it has some of the changes that has been made on the saw in 1959, the first year of the production. Dos anyone have other of these?? or bulletins?? The guy that i got the supplement from, did also had a tie pin... I could not help my self, i just had to owne it!!

 

[bikemike]

Here is my info on the contra lighting. Ditch the wind vein governor and let it rip. One of the guys at mn gtg had one and cause it not ratard proof it was a big hit. Of 50 percent of ppl that showed up ran it in some 20inch oak and was told not to worry about burying the bar cause you could not stop that old pretty power house on a fresh rebuild. What a saw and a cool lookin one to boot

 

[Eddy_t]

Here is my info on the contra lighting. Ditch the wind vein governor and let it rip. One of the guys at mn gtg had one and cause it not ratard proof it was a big hit. Of 50 percent of ppl that showed up ran it in some 20inch oak and was told not to worry about burying the bar cause you could not stop that old pretty power house on a fresh rebuild. What a saw and a cool lookin one to boot

Yes, without the wind-vane they will go up to 11krpm, but at this point, they eat bearings up at an alarming rate! Due to the repairabilty design of the 1106 series of saws, this is likely to mean new bearings, seals, crankshaft, piston and cylinder every 20 hours. The majority of participants on this thread are collectors and do not run hot-saws, the exception to this is macbob, but he builds the chinker copies for racing, whilst keeping his original for show. Over here (in the UK) they're generally used for running Alaskan mills, so speed is less essential, but that can be achieved with rim sprockets.


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[bikemike]

Yes, without the wind-vane they will go up to 11krpm, but at this point, they eat bearings up at an alarming rate! Due to the repairabilty design of the 1106 series of saws, this is likely to mean new bearings, seals, crankshaft, piston and cylinder every 20 hours. The majority of participants on this thread are collectors and do not run hot-saws, the exception to this is macbob, but he builds the chinker copies for racing, whilst keeping his original for show. Over here (in the UK) they're generally used for running Alaskan mills, so speed is less essential, but that can be achieved with rim sprockets.


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We didnt no load the thing but im shure it pulled 8 to 9 k in a heavy cut and didnt come close to getting hot. With a ample load on the saw you wont harm the bottom end and dont have to wait for it to clean out. Plus less carbon build up in exhaust port from not getting flooded out to drop rpm

 

[Eddy_t]

We didnt no load the thing but im shure it pulled 8 to 9 k in a heavy cut and didnt come close to getting hot. With a ample load on the saw you wont harm the bottom end and dont have to wait for it to clean out. Plus less carbon build up in exhaust port from not getting flooded out to drop rpm

They're not designed to run that way, the vane limits them to 7.5krpm. The saw was built for low down torque! As the muffler is extremely free flowing, you don't get much coking of the ports either.
In regards to wear, you have to remember, the every saw pictured in this thread as a contra is 45+ years old, they're already worn, increased rpm WILL kill them very quickly and unfortunately parts are like rocking horse poo! Increased speed makes more heat, and that's not including the massive slug of metal bouncing up and down in the cylinder.
As somebody who has restored and helped others restore these saws, trust me, extra rpm's are bad news given the tolerances of these saws!


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[Steffen]

I was wunderring if there is a any differens on the carbs from the 112 series and other used on the Contra or Lightning.
On my Stihl Contras there is used 112a and 112c carburators on most saws. On my original Contra S there is used 112d.

I have 2 Contras with the HL 74a carb, a bit rare carb and i have not seen many saws with that one.

Are there any differens between the carbs?? Maybe a Tillotson expert out there?? ;-)

 

[Eddy_t]

I was wunderring if there is a any differens on the carbs from the 112 series and other used on the Contra or Lightning.
On my Stihl Contras there is used 112a and 112c carburators on most saws. On my original Contra S there is used 112d.

I have 2 Contras with the HL 74a carb, a bit rare carb and i have not seen many saws with that one.

Are there any differens between the carbs?? Maybe a Tillotson expert out there?? ;-)

Venturi size is the main difference, other than needle location on the newer carburettors. The larger Venturi draws less fuel, so can run larger bars. I think skallywag posted up the sizes a while back, but between the hl112a (which I think is 20mm) and the ones used on the 090, (hl two hundred and something, which is 25mm) it uses 20% less fuel on the same setting on the same saw. This means the saw is leaner, so it can compensate running a longer bar. I think the hl74 was about 17mm, so it wouldn't lean out enough to pull the 5+ feet bars that a lot of the later models are seen sporting.


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[scallywag]

Here's a comparison between early and late Contra cranks. The cranks on the left is the later version as used in the Contra S and GS and early versions of the 070 / 090.
The most obvious thing at first glance is the bolt on weights added to the inside of the crank.



The later crank also had extra weight cast in. The early crank weighs 605 grams, the later 665 grams.



Extra oil galleries were also added....Note the heavier big end cap.




The gudgeon end also received an oil gallery.

 

[Steffen]

Unfortunately its not that simple, i have posted part numbers before in this thread.

The early Contras from 1959 and 1960 has the crank 1106 030 1200. The update with the manual oiler in 1960 came with the crank 1106 030 0300. This crank was also used in the S. it has the same crank as the normal 106cc engine.
The Contra G used another crank, part 1106 030 0703

The late Contras and the 070 used 1106 030 0400

The crank that you show with the extra weights added is the late crank and was used in both 106 and 137 engines. The extra weights added was done to kill some of the wibrations the early Contras had. I have run saws with both cranks, and you can feel the differens!!