Stihl High speed issue

[pboerschlein]

I am new to the forum, but have been reading alot of articles. Recently I purchased a Used 028. I have taken it all apart and replaced all that was not correct. I took a look at the piston through the exhaust and intake end and it looks great. I am having one issue with the saw that is frustrating me. It starts and idles great. But it does not rev up I have messed with the high and low speed screws as outlined in other posts, but cannot get it to develop a consistant high speed. I have cut a couple of face cords with it, and it will run good at about 1/2 throttle. But when I get into a big piece of wood that uses the whole bar and the saw starts to slow, I can squeeze the trigger all of the way and the speed does not change. So there must be something going on that I assume is causing the carbuerator to starve at the high end. It seems to do better with a full tank of gas. I have about 6-8 cords of wood sitting in the front yard to cut so PLEASE HELP!!!!!

 

[West Texas]

If I'm cutting a big limb/log I rev it up and go into the cut with full throttle; and, that's when I have someone adjust the H jet too, for best performance. If I don't have a helper and am working at home, I turn the H jet 1/8 out beyond the recommended setting, if that helps, I go out another 1/8th and when it makes it worse, I obviously go back an 1/8th. And if that first 1/8th out on the H jet makes it worse, then I turn it in (leaner) 1/8th of a turn. But I avoid getting it too lean, ruins the saw in a hurry.

But with that much wood to cut; don't screw around with half throttle, unless you are retired and have lots of time to kill.

 

[stihltech]

spring

Check for a weak choke spring.

 

[pboerschlein]

Does the choke spring come with a new air filter? I had my filter apart cleaning today and once I removed the plate behind the choke lever I did have issues with the spring coming off of the arm one time. Maybe I should go buy a new one?

 

[Lakeside53]

just take off the filter when warm and start up again. that will prove or disprove the choke spring.

 

[pboerschlein]

Should I be concerned about the fuel line or filter? Would it idle fine even if these were not working properly?

 

[Lakeside53]

yes, you need almost no gaas to idle. An almost complelely blocked carb inlet filter or fuel filter will let the saw idle fine. The inlet filter is inside the carb on the fuel pump side.

 

[pboerschlein]

Here is where I am at. I pulled the fuel line, the pulse line, large line from the carb to the cylinder and the fuel filter at lunch today and all are in great shape( no cracks or holes). I also pulled off the bottom of the carbuerator and looked for the carb inlet filter. I am not sure where it is. I sprayed through the inlet port with Carb Cleaner and everything there looks good also. I am also getting a spring to replace the choke plate spring to rule that out also. More ideas please.

 

[pboerschlein]

Put it back together tonight, and ran her and all is great. I suspect that the hose clamp holding the hose to the side of the cylinder was not tight. It seemed loose when I took it off. All I need now is to fine tune the carb now.

Can you verify mixture by looking at the color of the spark plug, should it be grey?

 

[Lakeside53]

It should be a light gray... but just tune it to stardard settings (1 turn out, or maybe 1.25 on your saw), then fine adjust. Final setting should be within an 1/8 turn of standard settings or you have other problems.