Stihl 028AV Super bogs at WOT

[Dino G]

Very new to this site but, can say I have found a boat load of incredible advise. Hoping maybe I can get some on a Stihl 028 Super. I got one from a friend for a friend and have had a couple issues. Ran horrible at first but idled perfect. Replaced the airfilter and plug and it fires right up. Took and ran about a tank of gas and fought with it to keep the chain spinnng. After letting it sit the chain was bound up tight. Long story short, the oil pump drive gear, oil pump gear, and clutch housing were melted like crazy. Threads on this site show exactly the melted mess I found. Albeit those photos here were not as servere to what I found. I have since replaced the clutch springs, the drum/sprocket, both oil gears and have also rebiult the carb to boot.
What happens now is the saw starts in three pulls from dead cold. Idles perfect and will go from idle to WOT without any hesitation. Let it warm up and stick it to a log and it'll reach high rev then then bog down as if you are pushing the bar in too hard. Once in the bog if you keep wacking the throttle it may start the chain in motion but you almost have to let it go back to ilde to get correct and expected throttle response. The brake seems to engage/dis-engage correctly with a good solid click in both directions.
Being somewhat new to chainsaws but, not new to small engines in any way, I thought is must be a fuel delivery issue. Thus the reason I also rebuilt the carb. (Walbro 16a). After the carb was rebuild it is acting exactly the same. I am starting to think that it must be something in the clutch area binding. It spins right up from idle to WOT and then bogs if its stuck to a log or in the open air. So, my concern is whatever caused the initial oil gears to melt is still going on.
Sorry for being so long winded and I hope I have given enough findings for one of the Guru's here to assist. If you need any more info just please ask. Thanks a mil,

 

[kykayaker27]

saw

have u got a compression reading yet, if low compression can run good till under load,hence why was burnt before somebody over working it to make it cut

 

[Dino G]

No, I have not had a compression test. But, it sounds like the next logical choice. I can tell you that it feels like it has a ton on the recoil. Meaning if you don't hang on tight starting it it'll give the wrist a heck of a snap. Feels tougher than my 024 that just won't quit. I'll get it to the shop and have them test it. Thanks KYkayker.

 

[kykayaker27]

compression testers are worth there weight in gold invest in one when money allows,dave

 

[Dino G]

Do you have a recomended manufacturer or product? What compression range should this saw be in?

 

[kykayaker27]

baileys have some nice ones ive found even the cheap ones work fine if taken care of i have a 028av has 130 and works good at 90 i put rings in it

 

[Dino G]

Well Dave,
Looks like you nailed it right on the head. The 028 showed 90 on the first pull with the compression tester and would consistantly go to 120 on the second pull. My little 024 showed 120 on each first pull. I did not give a second pull to see if it went higher. Saw some rings on Baileys for like $12.00. Guess at this point I almost have to give them a try. I am already just over $100.00 into it now. Having one of these and do you have any tips/tricks that I should be aware of as I pull this baby apart. Ring compression kit a good idea? Thanks again Dave, Dino

 

[atvguns]

Well Dave,
Looks like you nailed it right on the head. The 028 showed 90 on the first pull with the compression tester and would consistantly go to 120 on the second pull. My little 024 showed 120 on each first pull. I did not give a second pull to see if it went higher. Saw some rings on Baileys for like $12.00. Guess at this point I almost have to give them a try. I am already just over $100.00 into it now. Having one of these and do you have any tips/tricks that I should be aware of as I pull this baby apart. Ring compression kit a good idea? Thanks again Dave, Dino

You need to keep cranking the saw until the compression guage stops moving to get a accurate reading

 

[Dino G]

OH!!!! It did go to 120 on the second pull for like three tries. I never tried going any more and did not try more pulls on the little 024. Back out to the shop and see what we get. You guyson this site are a wealth of knowledge. I appreciate it.

 

[Dino G]

Here are the results:
028 90 lbs. on first pull. After 5 pulls needle stopped at 152 lbs.
024 120 lbs. on first pull. After 5 pulls needle stopped at 182 lbs.
So it seems to be lacking to some extent. But, not sure what these readings are really telling me,,, yet. Are these are #'s that you might expect?

 

[kykayaker27]

sounds as though ure compression is fine how well is it oiling lay a peice of cardboard on ground and point bar at it should throw oil onto the paper

 

[Dino G]

Oiler seems fine and is throwing plenty of oil. I did clean the bar well with a sawsalll blade and then pre-oiled the bar. but, in all honestly the bar is trashed. Blackened tip and is very worn along both sides. I think i may take the 16" bar off my 024 (if they match) and throw it on the 028. I did plan on replacing the bar but wanted to see better results before chucking another 60-70 bucks at it. Would this be a good test?

 

[kykayaker27]

yes very good i dont own a 024 but would think it should work but i may be wrong <hopefully somebody steps up with a definate yes or no good luck,dave

 

[PA Plumber]

After reading what you have written, I'd consider:

- Replace fuel filter

- Adjust high side on carb to 1 1/4 turns out and see if that helps. (Turn "H" needle clockwise until it gently seats, then turn counterclockwise 1 1/4 turns) It will likely still need some adjustment, but I'd see if it improves anything.

- Check wiring to make sure there are no bare wires; Especially where they could be contacting each other or metal.

- Check spark arrest screen to make sure it is clean.