Stihl 028 AV Super... is it worth fixing?

[Clarkbug]

I dont know what to tell you to expect, but I would imagine that the compression would be low until the new rings seat. Are you sure you have them clocked in properly? And what do you mean the exhaust plug? For the compression test, you dont need anything plugged.

Also, is your friends tester the kind that has a valve on the very end of it? If not, you could have a false reading.

 

[SteveoSupremo]

yes I put the rings on the piston and aligned to the keys before I used a ring clamp to hold the rings in while I slid the cylinder on pushing the ring clamps out of the way. everything was oiled with synthetic 2 cycle mix oil.

 

[SteveoSupremo]

ok so pulled the exhaust plug (rubber tire piece between muffler and exhaust port) and it pulls much like it did before I messed it up.

the compression reads 65 on first pull and 80 after the 3rd pull and it doesn't go up from there.

I'm thinking about gassing it up and trying it out.

any reason why I shouldn't?

 

[powerking]

...Somethings not right...That saw will not run with only 80psi...general rule of thumb is anything under 100 will not run.....any chance you can get another compression tester?

 

[PogoInTheWoods]

You never mentioned the results of your vac/pressure test.

 

[DJayawk]

Just finished reading all the pages in the this thread. I am in a very similar situation as you are Steve so I'm subscribing. Good job so far!

 

[SteveoSupremo]

You never mentioned the results of your vac/pressure test.

I haven't yet. I don't have the equipment. I'll try to take it to a shop and have them do it this weekend.

@powerking this is a brand new piston and rings what should I expect? Where should I check for problems?

 

[SteveoSupremo]

Just finished reading all the pages in the this thread. I am in a very similar situation as you are Steve so I'm subscribing. Good job so far!

Just PM'd You.

Good luck with your re-build. do you have a thread with pictures of your re-build? I hope to be as helpful as people have been to me.

 

[powerking]

I haven't yet. I don't have the equipment. I'll try to take it to a shop and have them do it this weekend.

@powerking this is a brand new piston and rings what should I expect? Where should I check for problems?

What direction is the arrow pointing on top of the piston? It should be towards the exhaust. I would have to go out on a limb here and say that the compression gauge is not working properly

 

[SteveoSupremo]

What direction is the arrow pointing on top of the piston? It should be towards the exhaust. I would have to go out on a limb here and say that the compression gauge is not working properly

Yes it's pointing towards the exhaust. I'll check again just to make sure. and maybe stop in at my local shop and see if I can borrow the use of their tools. Hopefully one of the 3 shops want my returning business.

 

[Mad Professor]

Who made your replacement parts?

Did you check ring end gap, and P/C clearance?

Stihl made made A , B, and A/B parts for top ends based on fit-ment. STIHL should have DECENT compression

If you rip it down, check piston deck height to wrist pin, might have a badley machined piston.

No brainer, got the SPARKY tight?

P.S. my 028S was rebuilt with OEM, > 20 years ago by me, it is my go to small saw.

 

[RiverRat2]

he went back with a meteor piston, one of the best aftermaket piston kits,,,

I would think comp should be 150-160 easy with a new slug and rings,,, cause that jug cleaned up really well,, You either have a bad leak or a bad tester,,,, any thing below 120 is not very good in my book,,, did you ever check the squish when you were putting it back together???

 

[PogoInTheWoods]

No brainer, got the SPARKY tight?

Wouldn't be one during a compression test. No brainer.:hmm3grin2orange:

Since he initially forgot the cylinder bolts, I'll put money on cylinder base leak -- maybe a torn gasket?



Poge

 

[powerking]

Wouldn't be one during a compression test. No brainer.:hmm3grin2orange:

Since he initially forgot the cylinder bolts, I'll put money on cylinder base leak -- maybe a torn gasket?



Poge

...or maybe NO gasket......Its easy to forget that when your trying to compress the rings and slide the jug back on...ask me how I know!

 

[SteveoSupremo]

...or maybe NO gasket......Its easy to forget that when your trying to compress the rings and slide the jug back on...ask me how I know!

Nope gasket is in there... I was kicking myself when I had to put it on after I had the ring compressor on there..... Had to pull all that off, and gingerly work the gasket over the piston. then re-assemble the compressor and slide the cylinder down. when I got close and got the manafold in is when I realized I should have put the bolts in first......

anyway I used a part retriever magnet to put the bolts in. and made sure the gasket was in properly with the bolts through first before tightening down with blue locktight.

I don't know how to tell what the squish is.

with the spark plug and no mufler it pulls pretty easy like I remember, with the plug in it pulls a lot harder when the piston is at top of the stroke.

I think the tester is not right for this application or there are too many losses in the hoses and fittings.

 

[SteveoSupremo]

It's Alive!!!

Decided just to go for broke and put some gas in it and fire it up.

appears to run ok. Carb was adjusted to 1 1/4 turns and I adjusted the lower until the chain stopped moving with the chain brake off.

It smoked a lot on startup but then I did put about an oz of oil on the piston, ring, bearings, etc.

I don't have a tac so what do you guys think of the tuning?

Stihl 028AV Super Start Up after Rebuild - YouTube

Thoughts?

 

[PogoInTheWoods]

do you guys think of the tuning?

I think your kid doesn't like it very much!

Sounds like it's 4-stroking OK at WOT, but idling a little high to me. Throttle response was sorta hard to gauge, but seemed a little sluggish.

But hey, go put it in some wood tomorrow and see how it cuts!

Good job sticking with it and getting it back up and running.



Poge

 

[SteveoSupremo]

I think your kid doesn't like it very much!

Sounds like it's 4-stroking OK at WOT, but idling a little high to me. Throttle response was sorta hard to gauge, but seemed a little sluggish.

But hey, go put it in some wood tomorrow and see how it cuts!

Good job sticking with it and getting it back up and running.



Poge

The boy definitely didn't like it! yea it didn't feel really responsive I thought thats how it was supposed to feel. How do I fix that? How do I know where to lower the low idle to?

 

[PogoInTheWoods]

How do I know where to lower the low idle to?

Bear in mind that the "low idle" is actually adjusted with the LA screw, not the "L" screw. The "L" screw is a "low" mixture screw as is the "H" screw a "high" mixture screw. The L screw will affect your throttle response and may take some time to dial in as the saw gets some time on it. Lots of info here on tuning if you're patient enough to sort through the search function for it.

Poge

 

[Clarkbug]

The boy definitely didn't like it! yea it didn't feel really responsive I thought thats how it was supposed to feel. How do I fix that? How do I know where to lower the low idle to?

Like Pogo mentioned, the LA screw is the one you want to tweak to get the chain to stop spinning. Its the one thats not directly in the carb. You should definitely search some on here, but Ill give you the rough break down.

Get the saw started, and keep it running long enough for it to get warmed up. Adjust the LA screw to make sure that your saw stays idling without you having to blip the throttle as needed. At idle, adjust the L screw in until it almost dies out. Then go the other way until you get too lean. Put it back in the middle. Now adjust the LA so that the chain isnt spinning. Now that you have played with your L adjustment, you need to re-do the high screw. There is a good sound clip from Madsens, and Brad Snelling on here has made a good video of what the saw should sound like in the wood.

Again, Im not a pro at this either, but thats the basic idea. Go ahead and search around here to get a good idea of what the full procedure is.