Stihl Contra Info Sharing Thread

[scallywag]

Stef, If you open the choke and look inside, you will see the step down in the venturi.

 

[Steffen]

Yes i know, but its the only thing i could messure

 

[scallywag]

I have seen GS saws here fitted with the HL 112d carb... There is a document in this thread that would suggest the last of the 137cc Contra lightning saws sold here were fitted with a 13/16" venturi ( 1" throttle bore ) carb, this carb was also offered as an after sales fittment.

 

[Eddy_t]

I can't see why you think the wider Venturi would give more power, the design is so a leaner mix can be achieved for running a larger bar, unless of course you are running a monster bar!


Sent from my iPhone using Tapatalk

 

[scallywag]

I can't see why you think the wider Venturi would give more power, the design is so a leaner mix can be achieved for running a larger bar, unless of course you are running a monster bar!


Sent from my iPhone using Tapatalk

Please quote my post where I state that!!.......And have you conisdered the jetting?

 

[Steffen]

With a lager displasement 137cc, you can get more air in. With a lager venturi you can easy the flow of more air, and with more air you can get more fuel. That makes more power.

 

[scallywag]

If the 070 HL 244a and the 090 HL 324a have the same size venturi 13/16" and all other parts interchange, what is left to accommodate the larger capacity of the 090?........It must be the jets?

 

[Eddy_t]

Please quote my post where I state that!!.......And have you conisdered the jetting?

I was referring to Steffens post, and yes, I've considered jetting!
The Venturi effect will draw more fuel through a narrower carb. The saw will still draw the same volume of air through into the cylinder, but a narrower Venturi will draw more fuel due to a higher air velocity. The wider Venturi draws less fuel, which helps for the larger bars, as max rpm is easier to tune.


Sent from my iPhone using Tapatalk

 

[Steffen]

Do any of you 1106 collectors have an original big bar for your Contras??
I have not been able to find any pictures of big bars from back then...

 

[Eddy_t]

Do any of you 1106 collectors have an original big bar for your Contras??
I have not been able to find any pictures of big bars from back then...

I have a bar with an 1109 p/n, but it's just a steel bar with the Stihl logo on it, none of the red-tipped stuff


Sent from my iPhone using Tapatalk

 

[Steffen]

Just got this pretty girl in my collection, is it possible to use the 090 piston in the Contra S?

Btw, scallywag is thinking about makeing some new heatcovers for the "S" cylinder, if any would need some of those ;-)

 

[scallywag]

Nice saw Steff!.......That model carb on it?

 

[Steffen]

Nice saw Steff!.......That model carb on it?

Its a HL 112D

 

[Eddy_t]

Just got this pretty girl in my collection, is it possible to use the 090 piston in the Contra S?

Is the S piston domed or flat? The 090 is flat. If they're both flat, it should work


Sent from my iPhone using Tapatalk

 

[scallywag]

Contra S and 090 pistons.





How the piston window height would effect port timing could be an issue.

 

[Steffen]

Maybe a set of 090 rings would do it then, dont like the sound of a 090 piston might or might not work...

 

[Eddy_t]

There's that much porting info on this site, just raise the windows slightly!


Sent from my iPhone using Tapatalk

 

[scallywag]

There's that much porting info on this site, just raise the windows slightly!


Sent from my iPhone using Tapatalk

Are you 100% sure this will work?....If not, please point me to the thread where it's been done.

 

[Eddy_t]

Are you 100% sure this will work?....If not, please point me to the thread where it's been done.

Pistons are the same diameter, gudgeon pin is at the same height. I've fitted pistons from one machine into another before, I did the same with the s-10 I repaired a few months back, personally I wouldn't bother modding the piston as it won't really affect the transfers.
Yes I am 100% confident!


Sent from my iPhone using Tapatalk

 

[scallywag]

So a 090 piston can be used in a Contra Lightning S ?