Speeds up...slows down...speeds up...slows down (Stihl 028).

[Adamam]

My increasingly stupid old Stihl 028av purchase seems increasingly stupid!

 

 

The newest problem I've discovered (having fixed the more glaring, pre-running problems) is this.

 

I've got it to idle (albeit too fast/chain creep, even with minimum idle screw setting), but when I rev it up, it's ace for about 30 seconds, then it goes UP and down and UP and down and UP and down as if I'm revving it up and down (I'm not).

 

The chain creep may be a bust clutch spring, haven't checked.

 

What's with the UP and down and UP and down thing?

 

I stripped the carb, and it looks ok (although I'm going to install a carb kit just for kicks). The only odd thing about the carb (Tillotson) is that there are no gaskets installed, just the membranes. I don't know Tillotson carbs, should there be gaskets between the case and membranes?

 

Ugh.

 

My first Ebay rip-off in over 400 transactions. Sold as 'excellent condition', 'just serviced' etc...seller not responding to emails...

 

 

Egg on my face.

 

[spudulike]

My increasingly stupid old Stihl 028av purchase seems increasingly stupid!

 

 

The newest problem I've discovered (having fixed the more glaring, pre-running problems) is this.

 

I've got it to idle (albeit too fast/chain creep, even with minimum idle screw setting), but when I rev it up, it's ace for about 30 seconds, then it goes UP and down and UP and down and UP and down as if I'm revving it up and down (I'm not).

 

The chain creep may be a bust clutch spring, haven't checked.

 

What's with the UP and down and UP and down thing?

 

I stripped the carb, and it looks ok (although I'm going to install a carb kit just for kicks). The only odd thing about the carb (Tillotson) is that there are no gaskets installed, just the membranes. I don't know Tillotson carbs, should there be gaskets between the case and membranes?

 

Ugh.

 

My first Ebay rip-off in over 400 transactions. Sold as 'excellent condition', 'just serviced' etc...seller not responding to emails...

 

 

Egg on my face.

 

 

The Tillotson carb should have a spacer gasket between the diaphragm and the case of the carb and also a spacer gasket on top of the pumping membrane between the pumping membrane and the top cover plate.

 

The gaskets often get welded together in time but check their positions as above - it is ommon to get them back to front.

 

The up and down high speed running may be a number of things but sounds like fuel shortage to me. Check the fuel filter, fuel lines (can go very soft over time) check the impulse line for cracks - see if you can remove it and block one end and suck on it:blushing: whilst waggling it - yes, I ma still talking chainsaws:001_rolleyes:

 

Check the breather isn't blocked, try running the saw with the fuel cap loose without too much fuel in the tank an easy way to see if there are breather problems.

 

The gauze filter in the pumping section of the carb is a common place for this type of issue. It is a circa 7mm recess in the pumpingsection of the carb.

 

There you go - you will be an expert after that lot!

[Adamam]

Thanks so much!

 

I kiss you!

[GardenKit]

 

I kiss you!

 

I was going to say what Spud said, but now I'm glad I did'nt!

[geoff]

I was going to say what Spud said, but now I'm glad I did'nt!

 

Clessic!

[spudulike]

A manly hug like brothers will do, not sure I want to kiss a bloke unless Adam is a pseudonym and Fearne Cotton has just purchased a Stihl 028:thumbup:

[Adamam]

Another question (still waiting for the carb kit before I do the rest of the suggested checks above).

 

Any advise very gratefully received, obviously!

 

What I believe to be the tank vent is just a small metal nipple. I believe this should have a tube attached to it with some grub screws in it?

 

The nipple isn't a valve then, just a plain nipple? If I hold the saw upside-down, I should expect to see fuel leaking from the nipple?

 

There's a hole in the case above the nipple, should the (missing) line that attaches to the nipple poke through the hole? If so, presumably it doesn't attach to anything, just sticks out?

 

Thanks!!

 

[Adamam]

Checked the impulse line, seems cracked.

 

 

Anybody know where I could get one? Also, how the hell to access it!!

 

[spudulike]

Yes - it should have a short length of tube and a grub screw/breather screw inside it.

 

If you attach a pipe on this connector, remove the tank cap and blow down the tube, you should be able to blow down it.

 

Hope this helps

[Adamam]

Yes - it should have a short length of tube and a grub screw/breather screw inside it.

 

If you attach a pipe on this connector, remove the tank cap and blow down the tube, you should be able to blow down it.

 

Hope this helps

 

Yeah, that's great (and what I reckoned), thanks!

 

This impulse pipe replacement looks like it requires the entire saw in pieces! Assuming I can even find a replacement impulse hose...

 

Think I've bitten off more than I can chew maybe. That said, I hate quitting!

 

Not much point spending tens and tens of quids on a saw this old I guess...