stihl 028super help needed

[Brian Carlson]

Working on a friend's saw and I have replaced crank seals, fuel line and installed a carb kit. Saw fires right up normally and runs good wide open but has an iratic idle. Sounds like it has an air leak. I inspected intake and impulse but found no issues. Saw does have a slight score line on exhaust side of the piston but has good compression. I have no way to pressure test it and wondered about some other options I may have overlooked.

 

[Onan18]

Not too familiar with those older Stihls Brian. I agree it sounds like a leak nut it could be a bad Welch plug in the carb. Is it old enough to have points?

 

[Chainsaw Jim]

There are a couple things to check before suspecting a bad carb. Intake boot, impulse hose, and the carb sealing tight against the boot.

 

[Czed]

Spray carb cleaner or something around the intake and even the new crank seals I've gotten bad one's before.
I've also had to replace carbs a kit didn't cure it.

 

[Chainsaw Jim]

Spray carb cleaner or something around the intake and even the new crank seals I've gotten bad one's before.
I've also had to replace carbs a kit didn't cure it.

Spraying carb cleaner on rubber parts and seals will destroy them.

 

[BuckthornBonnie]

New plug and fuel filter, too? Jug screws nice and tight?

I had a problematic 028 carb/- installed a new AM carb and it seems to be working well.

 

[redoakneck]

Should be electronic ignition if it is a super???

Did they make an 028 super not electronic??

See if the idle changes when you put saw on either side??

 

[kkemp]

My 028 s did the same thing . It didn't pass the pressure vac test . But I'm sure the carb could be messed up. I've had a couple that a carb kit didn't fix.

 

[XP_Slinger]

Spraying carb cleaner on rubber parts and seals will destroy them.

Yep...brake cleaner is safer for the rubber bits n pieces.

 

[Brian Carlson]

It is electronic ignition. I might just have to scrounge around the shop. I think I have another carb on a parts saw I could try. Swap the new kit in it and see. On this one there is only one metal ring on the very outside of the intake flange where the carb seats. Is there supposed to be a smaller ring seated in the throat like the 044 has???

 

[cus_deluxe]

It is electronic ignition. I might just have to scrounge around the shop. I think I have another carb on a parts saw I could try. Swap the new kit in it and see. On this one there is only one metal ring on the very outside of the intake flange where the carb seats. Is there supposed to be a smaller ring seated in the throat like the 044 has???

not on the few that i have messed with lately.

 

[cus_deluxe]

had an 028 super recently that had a massive air leak that ended up being the pto side bearing loose in its pocket. bearing (and seal probably at first anyway) was fine, just the crank was moving radially a bit.

 

[Duane(Pa)]

It is electronic ignition. I might just have to scrounge around the shop. I think I have another carb on a parts saw I could try. Swap the new kit in it and see. On this one there is only one metal ring on the very outside of the intake flange where the carb seats. Is there supposed to be a smaller ring seated in the throat like the 044 has???

Smaller inner ring is shown in the parts list

 

[kkemp]

. (On this one there is only one metal ring on the very outside of the intake flange where the carb seats. Is there supposed to be a smaller ring seated in the throat like the 044 has???[/QUOTE] ) all of the 028's I have have the smaller ring .

 

[Wood Doctor]

The Stihl 028's always amaze me at how finicky they are. I had one running exactly the way that OP described his. I swapped its carb with one that worked fine on another 028 and after that, they both ran flawlessly. Maybe I sealed off an air leak somewhere during the swap, but who knows?