Stihl 090 Building

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

eMGunslinger

ArboristSite Operative
Joined
Mar 15, 2011
Messages
241
Reaction score
56
Location
Louisiana
Cut to the chase, friend bet me I couldn't build a saw to outrun his stock Husky 3120. So I bought an 090 :rock:
I just need to if there are any great mods to do to really make this thing shine.
Muffler Mod, Adjust Exhaust/Intake, Chain, Bar, the works. Can be super crazy. I don't use it for a work saw so sky is the limit I just don't know where to look. I know its probably a very open question but I do not think I will need much to beat him. So if anyone just has a good list of things to do that would be amazing.

Also, Im new to the forums. So glad to be aboard.
 
You would have been better off buying a good used 088 and building that up. The port timing and shapes in the 088 are already a lot more ideal than the 090 for creating power at a higher RPM. That being said, the 090 can still be built up pretty strong. First thing you'll want to do is get a stronger carburetor, like a larger bore Tillotson HL. The muffler on the 090 is straightforward as is the ignition module. There's some work you can do to the piston and some porting work that will raise the power band a bit.
 
I would look at getting an 084 or 088 port popup muff mod or pipe. They noramlly turn around 14k but iam pretty sure youd be pushing it to turn 13k on a 090. Is this just cooky cutting or ........
 
Build a chainsaw with a V8 motor on it!!! :chainsawguy:
I wish but if I do that I cannot "sandbag" this guy and his saw, object is to kinda look like the underdog being he knows nothing...
#1 about chainsaws
#2 about stihls
#3 Hell I don't even think he know's how to sharpen his own chain
 
I wish but if I do that I cannot "sandbag" this guy and his saw, object is to kinda look like the underdog being he knows nothing...
#1 about chainsaws
#2 about stihls
#3 Hell I don't even think he know's how to sharpen his own chain

If you turn up with a 090 you won't be looking like an underdog...lol. Compared to modern saws a 090 actually looks more than it is. I'd find a 088 or 084 if in good order with not many parts needed. Or why not get a 3120 then when you toast him with what apears to be the same saw as him the look on his face... priceless:laugh:. Most importantly i would start exerimenting with chains, if you think he has a dealer sharpen his chains it shouldn't take much to beat.
 
Ok well from digging and reply's from members (Thanks btw)

Tillotson HL-360A Carb W/ High Flow Strainer-Unless someone knows bigger better
Lower and Widen Intake (If someone has exact numbers for this would be helpful)
Raise and Widen Exhaust (Also numbers would help)
Muffler
Remove Governor
Bigger Sprocket (9-10 Tooth?)
And of course while its torn down, Ill polish everything why not?
If anyone wants to give technical parameters thats fine. I've spent some time doing motors, but no 2 cycles.
 
Ok well from digging and reply's from members (Thanks btw)

Tillotson HL-360A Carb W/ High Flow Strainer-Unless someone knows bigger better
Lower and Widen Intake (If someone has exact numbers for this would be helpful)
Raise and Widen Exhaust (Also numbers would help)
Muffler
Remove Governor
Bigger Sprocket (9-10 Tooth?)
And of course while its torn down, Ill polish everything why not?
If anyone wants to give technical parameters thats fine. I've spent some time doing motors, but no 2 cycles.

Don't get too crazy raising the exhaust on an 090. Keep your exhaust lower and retain that compression so you can run a big sprocket and get your chain speed up. The 090 has a massive combustion chamber so you need to keep all the compression you can.

The 360A is an alky carb. You can convert it to gas with some parts and work. There are some other large-bore Tillotsons that are made to run gas.
 
Rieken's Racing: Tillotson Carburetors - OUT2WIN.COM
has it listed as a 2 cyl gas application, off chance you know another model to go with that may be better.
As far as intake and exhaust...probably wouldn't raise it to much .02-.03 up and down.
Can anyone recommend doing any up or down and just widening?
Should I do anything to the transfers?
And I realize getting crazy can mess up the compression, recommend raising compression right now its at the 148 mark?
 
I think my 394 will outcut my 3120 till you get to the 42" bar
But Ive never timed it, and I know for sure the 394 is lighter!

The 394 turns a couple more Rs and is not limited coil/and carb wise like the 3120.

Just saying...

But the 090s are awesome!
 
has it listed as a 2 cyl gas application, off chance you know another model to go with that may be better.

You might want to double check that. I know many kart guys who buy those and they tell me they're jetted for alky out of the box.

The 384b would make a good running 090 and you'd have better low-end performance with it. You don't necessarily need the biggest throttle bore you can cram on that motor.
 
Well finally got most of the parts in order went ahead and ported it a lot....Runs great, sorry no build pics took me about 6 hours between fabrications and smoke breaks. Ended up putting a new carb, matched muffler and cylinder ports, matched all intake ports, worked the transfers, modified air filer lol. Compressions right at 190 with no base gasket, its not easy to pull on
Anyone who has used a 090 the air filter sucks and I decided to adjust this. Cut the floor and trimmed the back out of a new top cover and made a new plate that bolts to the back of my carb. Moved the cover bolt to the side, and put the filter on top. Weight was minimal and doesn't get in the way.
Tillitson HL-360A carb, larger fuel tank grommet, larger fuel line, high flow carb strainer, new P/C, top cover, air filter.
Ill post a vid of it running went and broke in and seated the rings, ended up buying a new tach since mine told me I was turning 22k at WOT?!?!
I did clean up the port jobs as well but didn't take pics per usual, gonna pull it all down again anyway will get more
tinypic.com

tinypic.com

tinypic.com

tinypic.com

tinypic.com

Video of it is running stock when I first got it

[video=youtube;QUcEAtATJO4]http://www.youtube.com/watch?v=QUcEAtATJO4[/video]
 
Last edited:
No, I took this right after doing the rough work. I went back and cleaned it and polished the whole thing beveled and squared/rounded the corners to almost perfect. Just didn't snag photos of the complete but its all good. I was meticulous to detail on it. Also when looking down the cylinder, the black on the side is black marker.

No I haven't degree wheeled it yet, exhaust is down a lot and could go down and insane amount more. Only thing that worries me right now is what my tach was pinging at. It hit 22k exhaust temp wasn't over 300F with bar not in wood. In wood was pinging 17k, I think my tach is busted but I still almost soiled myself
 
Last edited:
No, I took this right after doing the rough work. I went back and cleaned it and polished the whole thing beveled and squared/rounded the corners to almost perfect. Just didn't snag photos of the complete but its all good. I was meticulous to detail on it. Also when looking down the cylinder, the black on the side is black marker.

No I haven't degree wheeled it yet, exhaust is down a lot and could go down and insane amount more. Only thing that worries me right now is what my tach was pinging at. It hit 22k exhaust temp wasn't over 300F with bar not in wood. In wood was pinging 17k, I think my tach is busted but I still almost soiled myself

I wanna hear that puppy running at 17k! :msp_scared:
 
Only thing that worries me right now is what my tach was pinging at. It hit 22k exhaust temp wasn't over 300F with bar not in wood. In wood was pinging 17k, I think my tach is busted but I still almost soiled myself

Don't believe that's possible. I'm guessing it's 1/2 that. Might need to change a setting in your tach.
 
Ill admit it screams like a banshee but I think the tach is just busted its wicked old. I really hope it isn't running 17k, probably blow up on me
 
Back
Top