I want to use my Stihl 070 AV for milling

[markvanzee]

hello,

I'd like to use my stihl 070 AV for milling.
View attachment 172123

It looks good but there are some things wrong with it.
I has a low compression. I don't know why. i pulled the muffler and the cylinder and checked for scratches on the piston. but it's clean. i checked for broken rings but there still intact. i checked the carb but its still super clean, decompression button works good as well. i don't have a compression guage but it's just so easy to start for a 100 cc saw..
View attachment 172122
starting this old stihl contra takes a lot more effort than starting the 070. but they have the same cc's. the 070 also dies when you actually put it in wood.

can a re-ring job fix this? or do i have to buy a new cylinder and piston (which is no problem at all, i can always buy a aftermarket stihl 090 cylinder and piston)

maybe it's a gasket issue? any thoughts appricated!

problem is i don't know the history of the saw, but i got it from a collector in belgium who got it from a stihl dealer, but he sayd it belongs to some dude who was in the timbersports.. but he didn't race with this saw or something, just owned it for fun i guess

but this metal plate between the carb and the cylinder does not looks stock to me...
can it be benefical?
View attachment 172121

close up:
View attachment 172120

any would really apprichiated any help.

sorry for my bad english, but there are no such forums as AS in my country.
I hope you guys can all see the pictures. this was my first attempt at uploading pictures.

thanks in advance

Mark van zee

 

[JDNicol]

hello,

It looks good but there are some things wrong with it.
I has a low compression. I don't know why. i pulled the muffler and the cylinder and checked for scratches on the piston. but it's clean. i checked for broken rings but there still intact. i checked the carb but its still super clean, decompression button works good as well. i don't have a compression guage but it's just so easy to start for a 100 cc saw..
starting this old stihl contra takes a lot more effort than starting the 070. but they have the same cc's. the 070 also dies when you actually put it in wood.

Am i right in saying contra doesn't have decompression button? Have you tried starting the 070av without decomp button? You say 070 dies when you put it in wood,
have you cleaned/checked to see if decomp is jamming on.

That metal piece is a heat shield, it is stock, my 070av has one.

 

[Roanoker494]

hello,

I'd like to use my stihl 070 AV for milling.
View attachment 172123

It looks good but there are some things wrong with it.
I has a low compression. I don't know why. i pulled the muffler and the cylinder and checked for scratches on the piston. but it's clean. i checked for broken rings but there still intact. i checked the carb but its still super clean, decompression button works good as well. i don't have a compression guage but it's just so easy to start for a 100 cc saw..
View attachment 172122
starting this old stihl contra takes a lot more effort than starting the 070. but they have the same cc's. the 070 also dies when you actually put it in wood.

can a re-ring job fix this? or do i have to buy a new cylinder and piston (which is no problem at all, i can always buy a aftermarket stihl 090 cylinder and piston)

maybe it's a gasket issue? any thoughts appricated!

problem is i don't know the history of the saw, but i got it from a collector in belgium who got it from a stihl dealer, but he sayd it belongs to some dude who was in the timbersports.. but he didn't race with this saw or something, just owned it for fun i guess

but this metal plate between the carb and the cylinder does not looks stock to me...
can it be benefical?
View attachment 172121

close up:
View attachment 172120

any would really apprichiated any help.

sorry for my bad english, but there are no such forums as AS in my country.
I hope you guys can all see the pictures. this was my first attempt at uploading pictures.

thanks in advance

Mark van zee

The 070 will handle your milling needs but the parts for those saws are not plentiful, so a break down could be very costly. If the piston and cylinder look good I would say new rings would fix your saw, there are no gaskets that would effect compression. I can not say if the metal plate is stock but it should help keep the heat off the carb and out of the air induction area, cold air makes more power.

 

[markvanzee]

Am i right in saying contra doesn't have decompression button? Have you tried starting the 070av without decomp button? You say 070 dies when you put it in wood,
have you cleaned/checked to see if decomp is jamming on.

That metal piece is a heat shield, it is stock, my 070av has one.

thanks for your helps. I have cleaned the decomp button from the outside and inside so i'm sure its not jammed.

no i don't start the saw with decompression button because it's so easy to start ..
i would've liked to have one on the contra.. that saw has some compression

 

[JDNicol]

Here is pic of cooling plate on my 070av, this is condition when i got it the saw hasn't been used much but probably never been cleaned;

Is the spark plug seated properly?
Does it idle OK without putting it in wood?

 

[dave k]

Nice clean saw and will do you for milling.
One of my 070's used to start very easy until I noticed a "chuffing" noise whilst it ran and it turned out a small bit of carbon was in the decomp, put small amount of light oil in and rotated the valve like bedding a valve and no problem.
There is a spring on the carb attached to the heat shield which is an add on for some reason ? I cannot see but I assume it is the correct carb age wise i.e the jets are as on your Contra ?
With regards to it's lack of power I assume the muff is not blocked from running on over rich fuel mix ?
Keep us updated and more pics !! See you over in the milling section. Just a thought have you checked the fuel pick up pipe is not soft and closing as you want more fuel ?

 

[markvanzee]

Nice clean saw and will do you for milling.
One of my 070's used to start very easy until I noticed a "chuffing" noise whilst it ran and it turned out a small bit of carbon was in the decomp, put small amount of light oil in and rotated the valve like bedding a valve and no problem.
There is a spring on the carb attached to the heat shield which is an add on for some reason ? I cannot see but I assume it is the correct carb age wise i.e the jets are as on your Contra ?
With regards to it's lack of power I assume the muff is not blocked from running on over rich fuel mix ?
Keep us updated and more pics !! See you over in the milling section. Just a thought have you checked the fuel pick up pipe is not soft and closing as you want more fuel ?

thanks for your help.
the spring is to get the throttle back to its original position. don't think that's original as well..

muffler is clean.

the fuel pick up pipe is the pipe inside the tank i guess? i'll check that out! thanks

 

[markvanzee]

Here is pic of cooling plate on my 070av, this is condition when i got it the saw hasn't been used much but probably never been cleaned;

Is the spark plug seated properly?
Does it idle OK without putting it in wood?

it idles and accelerates very good.

please explain what do you mean by seated? is that the gap setting?

btw did you notice the difference between your cylinder cooling fins and mine ? (picture notstock 1) your looks better finished. the cylinder on mine might not be NOS

 

[JDNicol]

I simply meant is the spark plug sealing. i.e the cylinder hasn't had the threads for the spark plug damaged, allowing the compressed mix to escape, there would be a mess around the spark plug it if it was.

 

[JDNicol]

btw did you notice the difference between your cylinder cooling fins and mine ? (picture notstock 1) your looks better finished. the cylinder on mine might not be NOS

I can't say i notice any real difference. On the clutch side if you look in the gap between the cooling plate and the cylinder, towards the bottom of the cylinder against the side casing you should be able to make out "MAHLE". It may well be covered up by dirt though.

 

[markvanzee]

I can't say i notice any real difference. On the clutch side if you look in the gap between the cooling plate and the cylinder, towards the bottom of the cylinder against the side casing you should be able to make out "MAHLE". It may well be covered up by dirt though.

checked it out but it doesnt say mahle so i guess it's a genuine cylinder
i just thoughts because some guy posted a reply saying the cylinder and carb are not stock and 2 minutes later he deleted his post don't know why

 

[markvanzee]

I would like to thank everyone for their input.

I have ordered new fuel lines, new fuel filter, new air filter, new rings, and new spark plug. will install that and see is she'll be ready for the mill.
i will post further progress!

 

[bigbadbob]

You need to give a compression reading . that will say a lot.
you need to do this with a good gauge with a schrader (tire valve)
in the tip. Might just need rings.

 

[JDNicol]

checked it out but it doesnt say mahle so i guess it's a genuine cylinder
i just thoughts because some guy posted a reply saying the cylinder and carb are not stock and 2 minutes later he deleted his post don't know why

Saying "MAHLE" would make it original. I think i can just about make out the upright of the M from your pic.
Red arrow shows you where you should be looking (what appears to be upright of M is slightly to the left of arrow);

EDIT;
forgot to say from your pics your carb is Tillotson HL 324A, which would make it original. Like already mentioned i don't know about that spring to return the throttle though, looks as if it has been added.

 

[pioneerguy600]

checked it out but it doesnt say mahle so i guess it's a genuine cylinder
i just thoughts because some guy posted a reply saying the cylinder and carb are not stock and 2 minutes later he deleted his post don't know why

I purposedly deleted my post as I had missed the photo showing the saw as an AV model, the AV model does have that plate and a cable controlled carb linkage, unlike most 070`s that are non AV. I did not say that the cylinder was not stock, it most likely is OEM but it may have been altered if the saw was owned by a racer. The exhaust port may have been raised to to gain RPM but in turn the engine loses compression, go too far and the saw will fall on its face in the cut.
Pioneerguy600

 

[markvanzee]

I purposedly deleted my post as I had missed the photo showing the saw as an AV model, the AV model does have that plate and a cable controlled carb linkage, unlike most 070`s that are non AV. I did not say that the cylinder was not stock, it most likely is OEM but it may have been altered if the saw was owned by a racer. The exhaust port may have been raised to to gain RPM but in turn the engine loses compression, go too far and the saw will fall on its face in the cut.
Pioneerguy600

thanks for your help. the guy was in timbersports but i don't think he used this one as a racer saw. i have pulled the muffler but it looks normal and was not filed in some way. it also sounds the same as my contra and if it would run more rpm you would most likely hear that. also the governor is still in place and that would disable the saw if it's over revving if i'm correct?

 

[markvanzee]

Saying "MAHLE" would make it original. I think i can just about make out the upright of the M from your pic.
Red arrow shows you where you should be looking (what appears to be upright of M is slightly to the left of arrow);

EDIT;
forgot to say from your pics your carb is Tillotson HL 324A, which would make it original. Like already mentioned i don't know about that spring to return the throttle though, looks as if it has been added.

thanks man i checked for 'MAHLE' but it's not there
i guess the cylinder is replaced sometime. it sucks when you don't know what happend to a saw in the past. but then again, this cylinder might not be so bad i'll just go milling with it and when it seizes or something .. i'll just replace it with a 090 cylinder and piston

 

[pioneerguy600]

thanks for your help. the guy was in timbersports but i don't think he used this one as a racer saw. i have pulled the muffler but it looks normal and was not filed in some way. it also sounds the same as my contra and if it would run more rpm you would most likely hear that. also the governor is still in place and that would disable the saw if it's over revving if i'm correct?

Yes the govenor does regulate RPM by closing the choke flap causing the saw to run over rich, the setting can be changed to allow the saw to gain or retard RPM by moving the spring arm higher or lower in the notches thus causing more resistance to the airvane linked to the choke linkage.
Pioneerguy600

 

[markvanzee]

Yes the govenor does regulate RPM by closing the choke flap causing the saw to run over rich, the setting can be changed to allow the saw to gain or retard RPM by moving the spring arm higher or lower in the notches thus causing more resistance to the airvane linked to the choke linkage.
Pioneerguy600

thanks for the info, i'm learning new things every day and not to forgot i've only been into chainsaws for a few months since i became interested in milling.

i also read that the governor can be disabled in some way? this would increase speed and power. is the power increase so large that it's worth the risk of seizing the cylinder?

 

[pioneerguy600]

Disabling the govenor on these saws is not a problem if the saw is tuned correctly for the task at hand. For short duration cuts the revs can be upped to around 10,000 RPM and then let the engine decide how fast it will run in the cut. For longer durations the carb should be set a little rich as the incoming fuel is what does the most cooling of the piston, the saw will REV a little slower but it can be run for extended periods without causeng heat damage to the engine, run the engine for 30 secs to a minute after a long sustained RPM cut to allow it to cool before shutting it down. The govenor is there to limit over revving when there is not enough load on the engine, like holding it WOT when not in a cut or maybe cutting off 2-3" limbs continously. My 070 and 090`s would not even need a govenor as I don`t needlessly blip the throttle and they run more in the cut rather than out, in the cut the carb tuning regulates the engine as to how high the RPM gets.
Pioneerguy600