090 help


Dormant hero!!
Dec 6, 2005
So. Oregon
ok i ran the 2 new 090's yesterday and the first one ran good till the muffler came off! so now i need 2 new bolts (studs?) for that. anyone know the sizes? also it seems when its cold i have to dump a little gas down the carb to get it to fire when cold, whats up with that?
the second one fires up and idles good but surges under full throttle. if i hold the govener its got plenty of power. what do i need to do here?


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They are both junk. I'll be willing to take them off your hands for $400 each, save you the hassle of trying to fix them.
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  • #3
haha ok i posted them to you today, theyll be there in the am:D and i threw in jerrys saw as a bonus:/:
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also any idea on the year of these? they appear slightly different
I'm here.:D I'll have to look up what size the studs are .I think an 090 is just a beefed up 070 so they should have about the same parts.I have an IPL for the 070 but not the 090 .

As far as that air vane governer I don't have a clue how to adjust it.I do know that an 090 has so much power you have to about sit on it to get the gov to kick in.The danged old things just seem to puttsy around at around 4-5000 rpm's or so,maybe higher.
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  • #7
i sunk em in wood yesterday and the surge would seem to bog it out. if i pulled out of the cut and pumped the throttle i could keep it running. thanks al
the gov. is mechanicle so i dont know if there is an adjustment. its tied in to the choke
On the 070 those muffler studs are M6 by 18.

The governer shows a small airvane plus a notched speed control base along with a little spring.

Now this is only a guess on my part but if that spring is too weak the airvane will just hold the engine to a snails pace.

I only have one old saw that originally had a governer,an old super 44 A Mac.I got tired of fooling with it and bypassed the danged thing.Good golly miss Molly that old bone shaker took off like a race horse.

I however don't think that would a good idea though on that 090 .The old Mac will take 10 thou plus rpm's I'm no sure that old Stihl would stand it or not.
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  • #9
the spring moves easily. at idle its wide open, at full throttle it drops back. what triggers it al, air flow?
Willie, sounds like air flow pushes it. Either tighten up the spring or try to find an appropriate replacement. I remember that type setup on old lawnmowers.
I *think* somewhere I've got a detailed workshop manual for the 090 as a pdf, only problem is I'm not sure that somewhere exists...
If it's any help I could post that for you (and a myriad of other manuals as pdf)
My .02 cents for what it is worth.

Bear in mind I haven't even seen an 090. Only in pictures . But, it is still a chainsaw.

I would still like to have one.

I am familiar with those air vane govs from some of the older Homelites I have worked on. Yes, the vane is controlled by airflow from the flywheel. There should be some kind of adjustment like a small knob or nut you can turn to loosen or tighten. I don't think an adjustment is going to make that big of difference myself. As long as the vane and the linkages to the carb are working free and not binding then I would say your ok. The vane would be just a matter of fine tuning if the rest of the saw is in good working order. I am not an old saw expert but I think the vanes function is to keep the saw from revving up too quickly to avoid damage to the internal engine parts and keep the rpm's from getting too high. Sort of like a rev limiter that is found in today's saw in the ignition module.

That is all superficial as engine speed is governed by the amount of air the throttle plate in the carb is allowing to enter into the combustion chamber and the vacumm that is being created by the movement of the piston.

Personally I would be looking elsewhere. One sounds like it might have mechanical issues like crank bearings and seals. The other might have some kind of fuel delivery problems. I'd be checking for dirt in tank, mushy fuel line, fuel filter partially plugged, crummy carb inards, throttle plate not opening all the way, metering lever in carb set where it should be ect ect .
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  • #15
sweet angus! thanks.

larry, ill be looking deeper, thanks. i dont really see it over reving as it does it even when its buried in a 36 inch oak log
No problem - shattered I can't find the workshop manual though :dontknow:
I've got the directions but they are on micro fiche so I can't post them.

This is basically what they say. Bypass the gov and set the max speed with the high speed jet to 11,000 rpms[I had no idea they would even run that fast] ,re hook the gov and it should hold at max 8,000 .If not the speed can be set by the preload of the quadrent spring .

From the picture on the micro it looks like the quadrent has notchs in it.So maybe move the spring to a tighter notch.That quadrent adjustment is in the fan housing by the looks of it .

This is word for word: If the governer does not come it at 8,000 rpm the preload of the torsion spring has to be changed.

To adjust the torsion spring move it to the max preload on the notched quadrent[toward the flywheel.] Then move the spring from notch to notch until it comes in a 8,000 rpm .

After completing adjustment secure the spring on the quadrent plate with alkyd resin.
Make sure before you screw with the governor that it doesn't have an air leak.

090's seemed to suck crankcase seals pretty easy.
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  • #19
i now have a 40 page print out parts blow up:D
thanks al, i did see that notched thing, looks like a timing marker. dollars to doughnuts thats the prob.