028AV Super needs help

[028AV Super]

My 028 AV Super w/ 24" bar is sick. I was cutting some downed trees on my property when all of sudden it started to load-up from idle to high RPM (had to play with the throttle to get to high RPM range). Now, it starts very hard as well. It alomost feels like something got plugged up while running. So far, it has sparks (don't know how strong it suppose to be), cleaned fuel filter, clean air filter, took out the carb and cleaned (fuel, air pressure through the ports) and inspected fuel pump diaphram, spring, valves, tank fuel line, intake hose, vaccum hose, muffler, etc. It still has the same problem with addition of hard starts. I set the carb setting back to original setting of 1 1/4 out on both L and H. The saw was very easy to start (3-4 pulls w/chock) and snappy throttle response prior to this. Please help.

 

[Fish]

Completely remove the muffler and inspect the piston for scoring damage.
Let us know what you see.

 

[Lawn Masters]

Isnt 24" too much for an 028? 16-18" is about optimal for that saw.

 

[cbfarmall]

Isnt 24" too much for an 028? 16-18" is about optimal for that saw.

Still shouldn't run that way.

 

[Ax-man]

I never learn my lesson to stay out of these what is wrong with my saw threads. Sounds like a crank seal opened up, like Fish said look at your piston for scoring.

Larry

 

[Lawn Masters]

Still shouldn't run that way.

True, but I was pointing out that 24" is too large of a bar for a saw under 65CCs.

It must be a crank seal that went bad, and is now causing the problems mentioned.

 

[028AV Super]

Thanks, I'll inspect piston for scoring damage tomarrow. By the way, this morning I put in a new plug and no change. The new plug had a less intense spark but had a longer with more diffusion compared to old plug. After numerous attempts, it did start up and had the same problems then shutdown on it's own. It almost sounds like it's getting enought fuel, or too much fuel. I tried to restart, I could hear engine wanting to light-off with each pull then the sound changed to a plain compressor sound (flooded sound) at which point I gentally (!@#$%^&*) put in back in the garage. One thing I notice the fuel supply line to the carb had some weather cracks, it not leaking fuel so I don't think it's the cause (plan to change it anyway). One thing I should mention is that the started to smoke more than usal since spring this year. I don't know that much about 2 stroke chain saw engins but, don't they slowly degrade showing some other syntoms? If piston scoring damage is detected what options do I have besides sending it to the Chain Saw Heaven... I would hate to take it in to Stihl service center find out the price tag...

 

[NWCS]

i just went through a similar deal with my echo brush cutter.. started smokin real bad.. then died out and just wouldnt run at all.. i rebuilt the carb thinking it was that.. nope.. pulled the motor off the shaft and was ready to pull the cyl and check the rings.. then i got the idea.. why do that when i dont have a gasket.. pull the spark arrestor screen and check that! AH 100% clogged! put the muffler back with NO spark arrester.. put motor back on.. she fired right up and runs again! muffler was just FULL of black slime and spark arrestor was solid HARD carbon. echo was bought about 94 or so.. this is the first time ive ever rebuilt the carb or checked that spark arrester.. and its had heavy commercial use. just a 21cc model with a blade meant for a much bigger machine doing what it was never ever suppost to be used for.. LOL

check that spark arrestor!

 

[028AV Super]

As for the 24" bar, I bought from a friend who had it since new who use to take it in evey year to Stihl service center for routine maintenance. I've had for almost 3 years and looks only slightly used. I have 2.5 acres with med-large Doug Firs throughout the property and have used it extensively. At first, it was intimidating as this was my first saw! Then I got use to it and got pretty good with it(I think...). I don't the story behind the long bar and what negative effects it has on the saw. Does it put too much load on the crank with longer bar and chain? It was working great for long time...

 

[028AV Super]

I did have the muffler front cover off few days ago and didn't find anything clogged but I guess I need to take it all the way off to inspect the piston. I'll look at it closer for any build-ups. Thanks,

 

[Lawn Masters]

To put it simply, the 24" bar is too long for a 48CC saw, that little saw just doesnt have the power to pull that much chain adaquately. you should downsize to a 16" or 18" bar, probably with .325 chisel chain, you'd have a really high speed machine.

 

[028AV Super]

Here is the latest,
I took the muffler off and did not have the carbon build up and screen were clean as well. The spring tension on both rings were good. What little I can see, the piston side were good too. As this was first 2 stroke engine inspection, I really don't know how critical to look at it, it didn't look like my 468 cid BB Chevy I rebuild couple of years ago. I check the cylinder wall was discolored (common on 2 stroke engines?) and did not see any gouge on them. I started the saw without the front muffler shroud and it started on third pull. It did sound more peppy (better throttle response) but soon died and same for few more starts. The engine acts like it's running out of fuel or ignition is cutting out. The air filter around the choke flap is wet with fuel when running and more during rapid throttle burst. The smoke from the engine were more noticeable due to absense of shroud.
Any other recommendations? Carb rebuild, change impulse and fuel hose, ignition coil? Please help you saw Gurus...Fish, ax-man, deadcow, cbfrmall
As for the correct bar and chain issue, I'll address it, if and when the saw is healthy again. Thanks Oldsaw-Addict for the correct 16-18" size for my peppy little saw (use to be...).

 

[028AV Super]

Update to the update!
Gents, I decided to check the impulse hose little closer by removing the handle assy. and taking it off all the way. To my suprise, I found a crack on the bottom side when I flexed it! I'm excited about this find and have my fingers crossed that it will be the fix! I did noticed three vertical gouges on the intake side of piston. I'm sure it has more life left on it. I'll let you know how it turns out.

 

[Lawn Masters]

That little crack in the impulse line will do it every time.

 

[028AV Super]

Happy 028 Super

Well,
After changing all the rubber hoses (impulse, fuel supply), it crank up fine! After little tuning and cutting for 4-5 hours, I was really happy (tired too). I guess with any worn engine the smoking went away after warmed up. I got to know my chain saw really good... Anyway guys and gals, Thanks for all your inputs.
Happy Cutting...

 

[rmihalek]

I'm glad you got your saw working well. I had a similar problem with my 028 and new hoses plus a carb rebuild solved it.

I read that in the western states, smaller saws used for limbing typically had longer bars on them to allow a felled tree to be limbed from one side. Since the bar was never totally buried in the cut, the length wasn't a problem. I don't think anyone would be happy cutting 20+" maple or oak in the eastern states with a 24" bar on an 028.

 

[028AV Super]

Hey Bob, I never had to cut a maple that size, but my 028 will stuggle with a hard wood of that size. I beleive it was use for limbing as well. Althought it's a high RPM saw, it lacks power for heavy cutting. It seems okay for the Doug-Firs here. By chance, did you do a engine overhaul on your 028?

 

[rmihalek]

I didn't split the cases to take the crank out and replace the bearings, but other than that I had the saw totally apart. I had 0.020" milled off the cylinder base and changed the port timing to specs mentioned here by EHP.

I still haven't run more than a couple tanks of fuel through it, so the new top end isn't even broken in yet. I did notice I had to back out on the H screw a quarter turn, so maybe the rings are seating in a bit and it's starting to burn more fuel.

 

[stihltech]

028

An 028 is not an 038 or 044, but properly tuned, cuts quite well.

 

[028AV Super]

Hey Bob,
How much did you spend on your 028 rebuild? Did you take to Stihl sevice center for the machine work? I assume you bought a new cylinder and piston?
I priced a cylinder/piston set at local Stihl center and it was around $230. Gee, for that much I'll put it toward a new saw with more power.
I appriciate the info.