Poulan Woodsmater 2250 will either idle, or rev, but not both.

Got another stumper

Got carried away and got a Poulan chainsaw in a package deal. A "Woodsmaster 2250, 2.2CID"
Older model, seems slightly more solid than newer Poulan stuff

36cc motor, Walbro carb originally.
Got it as a jumble of parts, but everything present. Put it back together and it surprisingly fired right up.
At that point, it would rev, but would not idle. I could start it at full throttle and seemed to run indefinitely but would die upon coming down.
One of the vibration-damper springs was also broken.

Not something anyone wants to buy in this condition, but also not worth scrapping since the saw looked cosmetically nearly brand new.
So I figured I'd buy a spring kit and a clone-carb for $20 total.

Springs were quite nice actually.

Saw idled perfectly! But then died under load.
I must have spent an hour trying to tune that stupid thing but I couldn't get it right. I would turn them both all the way in, then CCW the Low ~1/2 turn until it idled perfectly, then CCW the H extremely slowly. I couldn't seem to get results that made any sense when enriching the H. I'm prepared for the "junk clone carb is junk" reply.

It will either idle perfectly and die under load, or only start under full throttle, run perfectly, then die when coming to idle.

I would get the low speed circuit tuned in perfectly, then go for the high. I would adjust the high a bit, and then it wouldn't idle! And wouldn't re-start until re-tuning the low. Then it wouldn't rev!
It was this never ending loop of either low or high speed working, but never both.

What gives?


When does the low speed circuit taper off? How much overlap between H/L circuits on these small carbs? I'm familiar with the multiple curves on a CV carb on a motorcycle, for example, always 2 or 3 jets in contribution, but I'm sure these small carbs aren't as 'smooth'.

They get tuned from WFO backwards
So put the old carb back on and set WFO using the H needle alone to get the sweet spot between stalling rich & stalling lean.
Now screw the throttle stop in as far as it will go and see if the engine will run there by adjusting the L needle alone.
If you can do that then go back and readjust the H at WFO again then see if you can get it to run on the throttle stop again and back it out as far as you can then readjust the L
needle again

Then it is back to the H needle at WFO then the L at the lowest position on the throttle stop position
Repeat,
Repeat
Repeat as many times as necessary

The cross over is a volume of air through the venturii thing and the L is never turned off, it just pales into insignificance compared to the volume of fuel flowing through the H.
Even at WFO around 5% to 10% of the fuel will be coming from through the L jet.

I find it a bit easier or at least safer to remove the chain & clamp the bar in a free standing vice ( Triton Super Jaws ) till the engine will run & idle properly.
After that fitting the chain will then put a load on the engine and both jets need to be wound back a touch
Then the final bit is test in wood where usually the H alone will need to be backed off a touch more.
On my own saws I then engrave the turns from closed on the cover so I know where to start next time.
On customers gear I write it inside the filter cover with a paint pen.
It never fails to amaze me how many times these things "magically" change all by themselves cause the customer never touches them since you fixed it last time :laughing: