Stihl 090 rebuild

[Brewz]

Nice work mate.
We have a lot of red iron bark around here and its wonderful but hard as nails.
I like fast saws but sometimes slow and steady wins the race.
I have spent days noodling big rounds like that with an 066 and its hard on the saw and me.

I usually tune by ear myself but like to check the faster ones just to be sure now and then.
I thought I would hold the tach over the spark plug on the 090 and like I said, got some really funny numbers.

I will get it out bush one day and tune it to ear.

I am just curious about the tacho readings with a saw running points.

 

[rogue60]

Nice work mate.
We have a lot of red iron bark around here and its wonderful but hard as nails.
I like fast saws but sometimes slow and steady wins the race.
I have spent days noodling big rounds like that with an 066 and its hard on the saw and me.

I usually tune by ear myself but like to check the faster ones just to be sure now and then.
I thought I would hold the tach over the spark plug on the 090 and like I said, got some really funny numbers.

I will get it out bush one day and tune it to ear.

I am just curious about the tacho readings with a saw running points.

Don't know anything about tacho readings myself ,what's the fat safe rpm tune Stihl recommend for an 090?.
''slow and steady'' that's the deserving thing looks slow and steady for sure but I don't actually have a saw that can out cut it in hardwood no matter the cut size even 661 would/does take 2-3 times as long to do the same as in that vid..

 

[Brewz]

Around 8000 RPM I believe mate

I have raised this before when discussing the slow looking performance of the saws here in Aus.
If I put a big sprocket on a saw to make the chain spin faster, it actually slows the cut because the teeth cant bite and cut into the very hard timber properly.
The teeth just seem to skip over the wood only taking small chips as opposed to lots of large chips that I see in videos from over seas.

The 064 I ported runs great with a 8 pin in smaller wood but I will be running it with a 7 pin in normal use.

 

[Brewz]

Hey Rogue

Any particular reason you run hard nose bars over sprocket nose?
I have noticed you have a liking for them

 

[Redfin]

I have had issues getting it to idle but I got it sorted this arvo.
Grabbed my tacho and got some really odd readings.
To get the tacho to say 8000 rpm its drowning in fuel and hardly turning.
Lean it out so I sounds better but still rich and it says 14000 rpm.

First time putting a tacho on a saw with points for me...... What's the go???

My tach reads both 2 and 4 cycle. Points make no difference in reading rpm with a tach. Verify your tach is set for 2 cycle.

 

[Brewz]

its an old Stihl tach.
It has no settings

 

[rogue60]

Hey Rogue

Any particular reason you run hard nose bars over sprocket nose?
I have noticed you have a liking for them

Personally running both types of bars there is nothing in it for me .. I put a fresh chain on no matter the bar and it don't come off tell its had its last hand sharpen.
Am lucky in the sence my old man passed on the ins and outs of running hardnose bars. Many have trouble with hard nose bars using the same skills/techniques as running sprocket nose bars and the end result will usually be lots of smoke..
There are a few benefits running hard nose bars over sprocket nose bars and about twice as many myths as to why they are crap, the most obvious benefit is there is no bearing to fail just a vey hard working bar, also its not as easy to derail a chain even on the longer bars. there are more but really I can't be bothered getting into it no one runs hardnose bars anymore?. Someone will be alone any min to tell me they rob something like 3hp and ware out chains in 3 tanks of fuel and will never win a saw race or sum such lol.... if you're ever up in QLD call in would be happy to pass on all my passed on knowledge running stumping bars..

 

[Redfin]

its an old Stihl tach.
It has no settings

Mine is also an old stihl, if you hit reset it will cycle between 2 and 4.

 

[Brewz]

Someone will be alone any min to tell me they rob something like 3hp and ware out chains in 3 tanks of fuel and will never win a saw race or sum such lol....

Wont happen on this forum mate.
All that *s-word got left behind at the "other" place

I personally would love some tips but dont see a trip to sunny Qld any time soon.
I have a mate with some big old dirty ironbark stumps around his house he wants flushed.
I hate filling my nice sprocket tips with grit and I have an old 23ish inch hard nose that came on the 090 I am thinking of using.

Maybe you should start a thread with some instructional video's. I would love to learn the forgotten art of the hardnose as it certainly has its place in dirt filled Aussie hardwood!

 

[Brewz]

Now, back to the 090.
It runs better but still needs too much fuel to get idle speed down. Idle is really smokey and sounds rich.

I found the throttle shaft is wobbly in the carb.
Going to pull it out tomorrow and measure it to see if its the shaft or the carb that's worn.

I am considering just getting one of the after market Chinese carbs.
Does anyone have any experience with them?

 

[smokey7]

I have had pretty good luck with clone carbs. Ive used many for many diffetent things from saws, generators, mowers, weedwoppers, i honestly only had one issue that one wouldnt run, it was a float style for a snowblower. It had no seat for needle valve in the bowl. Other then that they almost always run way better then what i am replacing.

 

[CR888]

Around 8000 RPM I believe mate

I have raised this before when discussing the slow looking performance of the saws here in Aus.
If I put a big sprocket on a saw to make the chain spin faster, it actually slows the cut because the teeth cant bite and cut into the very hard timber properly.
The teeth just seem to skip over the wood only taking small chips as opposed to lots of large chips that I see in videos from over seas.

The 064 I ported runs great with a 8 pin in smaller wood but I will be running it with a 7 pin in normal use.

I have found this too in our hardwood, once chain speed gets to fast the chain don't function right and all you achieve is heat, blunt cutters and not enough lube.

 

[Brewz]

Pulled the carb of the 090
You can see how the throttle butterfly doesn't seat properly.
Pulled the throttle shaft and it is buggered.
The choke shaft has been repaired as well.
I think I will just get a new AM carb to get the saw running.
I am also going to put the OEM damaged top cover aside and put a Chinese one of it for use. I want to make an adaptop for a V stack and a K&N to replace the abysmal factory filter

 

[Brewz]

New carb and top cover on the way!

 

[Brewz]

While it is in bits on the bench, I might put a degree wheel on it and perhaps do a bit of grinding.

More power is never a bad thing

 

[Brewz]

Chinese top cover and carb showed up today.
The top cover is good. Fits well and good quality and finish. I will use it until I get the OEM one repaired.

The carb is a LOT smaller internally that the OEM Tillotson. The OEM carb is virtually strait through while the Chinese one has quite a pronounced venturi ring at the main jet. I recon 25% smaller.
The only problem with the OEM carb was the throttle shaft so I pulled the throttle shaft from the Chinese carb and it fit absolutely perfectly into the Tilly.
I am really happy to have the OEM carb fixed.

Now to fit it all up and see how she runs.

 

[Brewz]

Got it back together and it runs a lot better, as it should.

The chain still spins now and then at idle so I will look at replacing the springs.

 

[smokey7]

Thats awesome you could use the throttle shafts outta the china carb. Im wonder if it would have been felt down in power with the china carb?

 

[Brewz]

It would have for sure........ way smaller, like the size venture on an 066 carb.

137cc pumps some air!

 

[Brewz]

Took it out and ran it today.
I went to a big dry log that's really hard and 2 foot thick.
My ported 066 found it challenging.
I tested the 2100 in it a couple weeks ago and it did it well but it was working hard. The 076 took it about as well.
The 090...... dogged it in, lifted the handle hard and it just plowed the way!
I was like....

I fired the 066 back up and no amount of chain speed was going to make it cut faster in this hard timber.

It definitely has a use in Aussie hardwood!