My very first top end rebuild 028 AV Super...advice needed.

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

thombat4

ArboristSite Guru
Joined
Oct 2, 2007
Messages
735
Reaction score
259
Location
I live in Cleveland Ohio
So I've been putting off working on this saw for over a year now. I bought it from a local police chief who bought it new however many years ago that was. I paid $80 for it in non-running condition. I figured with my knack for getting things running again that I'd have it running soon. Suffice to say it didn't happen. It sat in a container in pieces until I finally made time to really look into it. So the chief tells me he was running the saw when all of a sudden it just died on him and he couldn't get it going again. He went and bought himself a new 271 farm boss. Anyway, I replace all the usual things that i could think of that could possibly be the problem like fuel line, carb, impulse, breather and still couldn't get it going. I'd never done anything close to a piston/jug replacement before and the saw still seemed to have compression and the piston didn't "look" that bad to my untrained eye anyway. Needless to say that's exactly what the issue was. I watched a few videos, read a few threads and decided to dive into it. Yes the piston was shot. Scored and rings were "welded" in place. Would bad mix do that much damage? I will post pics when I get home later. I probably should have asked here first but I went ahead and ordered a top end overhaul kit from HL Supply. I got everything installed and it doesn't seem to want to start under normal operating procedures. This morning I poured some mix in the plug hole and it started and actually ran for almost a minute although I could tell it wanted to die...kept bogging down badly. My question to you guys that are way more knowledgeable than I am on this kinda thing is, what should I be doing at this point? What are the proper steps to take to see if I can get this saw running again? Apparently this is a very nice saw from what I've been reading. It would be sweet to get it going again. I'm not great at tuning but I can still learn and take advice! Thanks for any help.
 
If you're gonna make a habit of working on chainsaws you gotta pressure and vacuum test them. It's a good idea to do it before you pull a saw down that way you can eliminate possible causes of the failure. But it's always a good idea to p/v test after you hack into one.

A Mightyvac MV-8500 is a chainsaw mechanics best friend.
 
If you're gonna make a habit of working on chainsaws you gotta pressure and vacuum test them. It's a good idea to do it before you pull a saw down that way you can eliminate possible causes of the failure. But it's always a good idea to p/v test after you hack into one.

A Mightyvac MV-8500 is a chainsaw mechanics best friend.
Thanks for that tip Oz:numberone: I DO intend to get more into repairs.
 
I'm fairly new on chainsaw so there's other that probably have better advice. But all Engine in general need compression, Fuel and ignition. I bet your problem is fuel...but do you know what the compression is and did you do a leak down test. It ran for min so it got ignition and compression. Pretty much leaves Fuel. You replaced the carb, fuel line, and impulse. Did you change the fuel pick up filter. Did you preset the High and Low Needle valves on the carb or make any adjustments? You might throw the old carb back-on see if that helps. You dump the tank and have fresh fuel correct. Did you check the carb rubber boot.
 
I'm fairly new on chainsaw so there's other that probably have better advice. But all Engine in general need compression, Fuel and ignition. I bet your problem is fuel...but do you know what the compression is and did you do a leak down test. It ran for min so it got ignition and compression. Pretty much leaves Fuel. You replaced the carb, fuel line, and impulse. Did you change the fuel pick up filter. Did you preset the High and Low Needle valves on the carb or make any adjustments? You might throw the old carb back-on see if that helps. You dump the tank and have fresh fuel correct. Did you check the carb rubber boot.
I currently don't have and leak down testing equipment. From pulling the starter cord it has way better compression than it did when I bought it. It feels like a brand new saw when it comes to compression. I did put the old carb back in and I did not make any adjustments to it. The fuel filter is new. I've only ever used fresh fuel in it. By "carb rubber boot" do you mean the intake manifold? If so, I did not change it out. Thank you for the feedback! I'm sorta new at repairs myself.
 
I had problem with 034AV it would fire not run. I had bad fuel line with crack in it. My carb had bad reeds. after the rebuild I started with my needle valves 1 1/2 turns from closed. I kited it and set the needle and seat solved my problem. The Chinese cylinder I have one but haven't run it yet. One thing I learned is makes sure the ports are beveled good or could break a ring I'm told. I posted some stuff on my 034AV...and my cylinder. The Chinese cylinders are a crap shoot I'm told. You can remove the plug and place a piece of solder in the cylinder and check the clearance piston to the head with calibers but I don't think that a concern... It runs so...it got be fuel.
 
You can remove the plug and place a piece of solder in the cylinder and check the clearance piston to the head with calibers but I don't think that a concern... It runs so...it got be fuel.
Latest update: So when I got home from work I tried starting the saw and it started up and ran on it's own just fine except the chain spins rapidly at idle. I tried adjusting the idle screw and I got it to slow down significantly but it didn't stop completely. It would stop and then it would creep forward sporadically. I'll have to try working with it some more when I have more daylight. But the good thing is it seems to want to run and it has a lot of power. Just a matter of fine tuning I suppose.
 
did u try adjusting the low speed screw as well? agree its possible you have an air leak but its not as common as people think. assuming the fuel line, filter, and pulse hose are in good shape, and low speed adjustment doesnt get it to behave then you may have something more going on. mv8500 is what i got for pressuretesting, youll need an adapterto go in through the spark plug hole, or test through the pulse line but that can be a little difficult with the carb in place.
 
IMO - It has an air leak somewhere. That will cause a fast idle, it will also cause your new top end to become just like the old top end rather quickly.

You need to pressure and vacuum test the saw to make sure it's not leaking air.
Well I certainly don't wanna undo the work I put into it. I'll have to research how to perform those leak tests. Thanks for the input.
 
did u try adjusting the low speed screw as well? agree its possible you have an air leak but its not as common as people think. assuming the fuel line, filter, and pulse hose are in good shape, and low speed adjustment doesnt get it to behave then you may have something more going on. mv8500 is what i got for pressuretesting, youll need an adapterto go in through the spark plug hole, or test through the pulse line but that can be a little difficult with the carb in place.
I have both the hi and lo turned out at 1 1/4 as it indicates on the cover. The fuel line, filter and pulse hose are all OEM new. Will be looking into pressure testing gear and how to use it next. Thank you for the help.
 
Someone posted a good guide to proper carburetor tuning on here, it's worth a read. 1 1/4 turn is just the starting point. Obviously if your chain is spinning out at 2500 RPMs your clutch has bad springs, but if it's spinning because you're at 3500+ RPMs you either have an air leak or you're carb is out of tune.
 
I started as member because I had a similar project on 034AV. It had a fuel issues plus I thought I could buy cheap cylinder just rebuild the saw and I'm good to go, but I found out it could be little more involved. Not sure how much you want spend on test equipment, or how hand you are or how far your are willing to go on your own. But I got warn you this hobby can get addicting.
With the old cylinder toasting, it either ran lean due some type of fault or fuel. You really won't know until you ran a leak test. There's a lot information on how do this out there. Depends on how much money you want to spend. If the test fails you have to pull the flywheel and the clutch to check the seals. Or you can just replace the seals hope for the best, but you should really do the test. Also, the rubber boot between the cylinder and carb could also be an issue. The shop around here charges $40 for pressure/leak test. I bought a Mityvac MV8510 Silverline Elite Hand Pump $59 which I thought was the best for the money. There's cheaper vacuum/ pressure test equipment and better one as well, but you need one that does both Pressure and vacuum. I made all my blank off and rigged all my own fittings. You can get rubber at the Auto Parts store. A flywheel puller would be needed Farmertec Flywheel Puller Kit Two Tools in One for Many Stihl Chainsaw Rep 1110 890 4500 $11, thou some use a knocker... I'm not fan of beating on cranks. Your saw is smaller so not sure if you can get away with screw to pull the seals or you'll need a seal puller such as Lisle 58430 Shaft Type Seal Puller $14.66. It really starts adding up on the tools. These tools are what I bought, some of which may not work on your saw you should verify if your thinking about going this way.
Attached are some example of my leak down testing on my 034 super . I took a old spark plug and made my own vacuum fixture. Just be careful don't put the seals in to far if you decide to install new ones. Its really hard to say if you have carb tune issues or a leak but the toasted original cylinder something happened... just replacing the cylinder and impulse line may not have solved it. You really need a tach to tune the high end to be sure too. I bought https://www.amazon.com/gp/product/B07142Q3BL/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 $35. Again, there a lot smart guys on this site that may have better advice. I wish you best on this project, I find it rewarding so...I'm hooked, it now my hobby, learning as I go.
 

Attachments

  • IMAG4716.jpg
    IMAG4716.jpg
    468.4 KB · Views: 9
  • IMAG4717.jpg
    IMAG4717.jpg
    325.5 KB · Views: 7
  • IMAG4719.jpg
    IMAG4719.jpg
    472.5 KB · Views: 7
  • IMAG4723.jpg
    IMAG4723.jpg
    381.3 KB · Views: 7
Back
Top