Hi guys, I have a still 046 that goes well, I know how to tune it, never an issue.
but this MS250 that I bought second hand on impulse just wont idle...
it starts easily, hasn’t been tested but feels like it has good compression.
whats happening is that when it idles I can’t tune it to run at a low enough idle that doesn’t drive the chain.
I can get it to idle stable-ish (mostly) without it driving the chain (still with the issue below though) by using a significant amount of the idle screw (not the low jet) wound in. which is not right but it’s the only way I’ve found to make it idle sort-of ok.
So the weird thing that it’s doing which I’ve never come across before is that when the saw is moved around it revs and drives the chain fairly fast (not cutting fast but unsafe) no touch if the throttle at all, simply move the saw around, especially tipping it side to side and it will rev. it doesn’t matter how I adjust the saw, it does this.
If I adjust the low jet to about where i think it should be (saw starts, idles a bit but I have to keep a finger on the trigger to throttle every now and then to keep it running), I can actually keep it running by moving around, it revs fairly high though. Stop and it will stall out after 10 seconds or so.
if I start the saw, have it sitting on the ground, as above it’s a fine line but I can get it to run and idle ok-ish without it driving the chain as below but as much as simply tipping the saw to one side can make it rev like crazy (for what should be idling anyway).
I’ve fitted a new carb rebuild kit and cleaned it out - made no perceivable difference.
has a new spark plug (didn’t suspect it was part of the issue but had one hanging around)
Fuel filter and fuel line are new.
I haven’t replaced the impulse line but it looks good to my eye. Certainly no signs of cracking or perishing.
When running it revs up high nicely and cuts well, it just won’t idle as it should.
What could be causing it to rev when moving it around?