zoltan

Thanks for the replies and advice everyone. I have new seals so I will fit those and take it from there. It looks like special tool time to get the magneto off the crank without damaging it The impulse hose runs from the back of the crank case under the port through to the handle and carb. It is clear as I ran some air through it, I ought to check it for a split as it is the only other connection between the carb/linkage and the crankcase and would certainly be affected by movement between the handle and the rest of the saw motor I suppose it is hard to say if I am compensating for the problem with the idle settings as I have tuned the saw around the problem when I thought it was a carb issue

Hi, I'm very new here. I don't work as an arborist but use chainsaws for firewood. I'd appreciate some help diagnosing a problem with my Stihl 028AV Its history: fairly well used Ebay purchase when I got it, been treated to a new piston and rings, a carb overhaul kit and a new bar, sprocket and chain. Was running nicely but has deteriorated in last couple of months It starts fine and idles. Running 50:1 on Stihl oil and ordinary unleaded. Clean fuel and air filters When it is warmed up and I try to cut, the power surges unless the saw is held down onto the wood with a small degree of pressure, held lightly then you kind of have to feather the throttle otherwise it will cut out. When running it has sufficient power to cut properly. It is impossible to up cut with the saw so my initial theory was a split in the rubber sleeve that connects the barrel to the carb. As if the downwards pressure was closing the split and it was gulping air and running lean without the saw being pressed down. I took this out at the weekend but is was perfect, no perishing, no damage. Next area to check is if fuel hose is getting sucked flat but this doesn't explain why the saw is sensitive to being pushed down on its rubber mounts as the tank, hose and carb are all fixed together in the handle, separate from the engine Anyone have any other ideas? I'm becoming somewhat stumped by this Do dicky crank seals give these symptons? Thanks Colin