Help 028 super engine issues

[Adam Smith]

Needing some help please. Ive got an 028 super very clean little saw. I bought it not running so when I recieved it I put a new fuel line and filter, Impulse line and took carb apart and cleaned. All the diaphrams looled good under a magnifying glass. Problem is after it warms up when you go to full thorottle under no load it spins up to about 8000 or so and then just boggs out like you shut the kill switch off. Im sure its getting air somewhere just not sure where. With engine running and warm you can put it in a cut and apply light preassure on bar in the left and right positions and the saw does not try to speed up or slow down. Any suggestions would be greatly appriciated. Thanks

 

[z71mike]

It's gonna sound redundant lately, but it could be crank seals. Have you done a pressure/vac test? What's your compression?

 

[Adam Smith]

No Mike I havent pres or vac tested yetI will get to it tommorow. It has around 140 pn the comp. I cleaned this saw up and cut a little with it and was pretty happy with the way it was running and actually had it posted to sell on the Big E. Luckily I had it out Thursday and was gonna give it another look over and it started its stuff so I got it pulled off before it sold. Just curious where to start. How much vac should one hold and for how long?

 

[Arrowhead]

Make sure the tank vent is working properly.
Also coils are known to go bad once they get warm.

 

[Adam Smith]

Thanks Aarowhead I put a new vent tube line on it after it started acting up because it was cracked between the tank nipple and the screw in plug inside the line. I also wondered about the coil myself, Although when it acts up it sounds like it is a fuel/air issue. But not for sure Im pretty new to the saw world so any advice is appriciated. By the way what is the purpose of the plug in the tank vent hose and should it have a hole through the middle of it?

 

[Arrowhead]

The little screw in the vent hose? It keeps the fuel from pouring out, but still lets air in the tank from around the threads.

 

[Adam Smith]

The little screw in the vent hose? It keeps the fuel from pouring out, but still lets air in the tank from around the threads.

Yeah sorry I just read about it on a thread below mine on the forum here. Guess I need to open my eyes a little

 

[pioneerguy600]

Now to me I would be looking at the fuel delivery side of things. Sounds like the engine is not getting enough fuel to get to WOT. Possible that the metering lever is set too low, that the diaphragm and gasket is in the wrong order or that there is foreign material in the high speed circuit. How far out from lightly seated is your H screw set?

 

[Mad Professor]

Thanks Aarowhead I put a new vent tube line on it after it started acting up because it was cracked between the tank nipple and the screw in plug inside the line. I also wondered about the coil myself, Although when it acts up it sounds like it is a fuel/air issue. But not for sure Im pretty new to the saw world so any advice is appriciated. By the way what is the purpose of the plug in the tank vent hose and should it have a hole through the middle of it?

Did you use OEM vent hose line?

If not the grub screw may not be letting enough air in to vent the tank. Also not all generic hose is fuel compatible so even if it works initially problems can arise with use.

Could try loosing the fuel cap, tilting it a bit to the right without out much gas in the tank, and see if it revs O.K.. If so a vent problem.

 

[Adam Smith]

Did you use OEM vent hose line?

If not the grub screw may not be letting enough air in to vent the tank. Also not all generic hose is fuel compatible so even if it works initially problems can arise with use.

Could try loosing the fuel cap, tilting it a bit to the right without out much gas in the tank, and see if it revs O.K.. If so a vent problem.

Im gonna grab a coil for this thing tommorow, Ive almost convinced myself that its a firing issue. Ive tried the no fuel cap with no help and also tried unhooking the vent tube all together with no help. Carb all looks good. I noticed today while messing with it for a minute that when I put the tach on it that I have to hold it really close to the plug or it dosent read and also when it cuts out on thorottle the tack goes to nothing, Thinking Maybe that I have found the problem. Does this make sence to anybody els or am I off my rocker

 

[Mad Professor]

Before you invest in a coil check all the wiring too it.

The coil wire: especially at the coil, where it passes the tank/crank housings (can get worn/pinched here due to bad routing or worn AV mounts, and the connection to the plug (spring inside plug cap).

Then the ground wire and ignition switch.

 

[z71mike]

Yup. Before ya dump a million bucks on a new coil, be 110% certain that's what the problem is. The high price of a new coil doesn't REALLY hit home till you install it and realize the problem didn't go away.

 

[Adam Smith]

well I tried a used coil off of a running saw with no help and put a new kit in the carb with no help. Inoticed while adjusting on the carb that with the H screw screwed as far out as I could get it without it falling out It seemed to really help the saw out it still was not perfect but it did help. I bought this saw and it came with the muffler alreaddy muff modded. could this be causing my issue if it has to many or too big of a hole in it . It has five holes in the cover of it a little bigger than a quarter of an inch in diameter?

 

[Stihlofadeal64]

Now to me I would be looking at the fuel delivery side of things. Sounds like the engine is not getting enough fuel to get to WOT. Possible that the metering lever is set too low, that the diaphragm and gasket is in the wrong order or that there is foreign material in the high speed circuit. How far out from lightly seated is your H screw set?

+1 for me here. Just took apart a saw that was having this same type of problem. (Not insulting your intelligence at all) but check the order of the diaphram's and gaskets in your carb and the metering lever height. All three applied to the saw I just worked on -- the gaskets/diaphram's were not right and the metering lever was low.

 

[pioneerguy600]

well I tried a used coil off of a running saw with no help and put a new kit in the carb with no help. Inoticed while adjusting on the carb that with the H screw screwed as far out as I could get it without it falling out It seemed to really help the saw out it still was not perfect but it did help. I bought this saw and it came with the muffler alreaddy muff modded. could this be causing my issue if it has to many or too big of a hole in it . It has five holes in the cover of it a little bigger than a quarter of an inch in diameter?

Putting a kit in a carb without doing a thorough cleaning job on it is of little use at all. The carb is not flowing enough fuel at all if the H needle is out more than 1.5 turns. The carb needs to be clean in all of its channels and jets. Did you remove the H&L needles and the metering lever and needle valve, then flow/spray carb cleaner through these ports and verify that the liquid comes out through the jet holes into the venturi? Look through the well where the needle valve sits and verify its clear.

 

[Adam Smith]

Putting a kit in a carb without doing a thorough cleaning job on it is of little use at all. The carb is not flowing enough fuel at all if the H needle is out more than 1.5 turns. The carb needs to be clean in all of its channels and jets. Did you remove the H&L needles and the metering lever and needle valve, then flow/spray carb cleaner through these ports and verify that the liquid comes out through the jet holes into the venturi? Look through the well where the needle valve sits and verify its clear.

I cleaned the carb in a cleaning solution that I use on my bigger holley and demon carbs and all channels and holes are clear and clean. Now I cannot promise that the carb is correctly put back together as I put everything back in the way it came apart whick does not mean anything of course. Does any one happen to know of a schematic I can find for a walbro W 16 B carb? Also is there a certian height that the metering arm should be adjusted at or is it simply trial and error?

 

[pioneerguy600]

I cleaned the carb in a cleaning solution that I use on my bigger holley and demon carbs and all channels and holes are clear and clean. Now I cannot promise that the carb is correctly put back together as I put everything back in the way it came apart whick does not mean anything of course. Does any one happen to know of a schematic I can find for a walbro W 16 B carb? Also is there a certian height that the metering arm should be adjusted at or is it simply trial and error?

Did you spray any cleaner through the ports where the H&L needles came out of. The reason I ask is that there can be dirt in there that does not come out by just soaking a carb in cleaner. Many carbs I see that were kitted and then won`t work right are ones that did not get those ports cleaned out. If the H port and the channel to the jet is plugged then you won`t get enough flow of fuel through the carb to run the engine at WOT.

 

[pioneerguy600]

As to the setting height of the metering lever we need to know the model of the carb as each one differs in setting height. There is a special gauge that is used to set the heights of the Walbro carbs, The WA series is set .060 below the top machined surface of the carb body, the metering lever is down in a depression/bowl. The top of the lever where the tip of the weight on the diaphragm contacts it can be set flush with the surface of this bowl bottom. If your carb is a model WA check out this schematic>

http://www.walbro.com/media/21895/WAseries.pdf

 

[Adam Smith]

Im getting ready to tear into it here in a few minutes Im looking foward to seeing if things are installed wrong or not. I sprayed carb and choke cleaner through all channells and holes in carb and chased with regulated compressed air. The carb is a walbro W16 B I believe Ill know for sure here in a minute thanks very much for the help your are giving this thing has gotten me stumped. Will update in a minute.

 

[Adam Smith]

Im getting ready to tear into it here in a few minutes Im looking foward to seeing if things are installed wrong or not. I sprayed carb and choke cleaner through all channells and holes in carb and chased with regulated compressed air. The carb is a walbro W16 B I believe Ill know for sure here in a minute thanks very much for the help your are giving this thing has gotten me stumped. Will update in a minute.

Well I figured it out. The choke flap that is built into the air filter wassucking shut under WOT. I pulled the flap out of it and tried agian and bam it fixed it. Thank goodness, I wasnt to far from putting it on Ebay for parts. Now I feel good about selling it as a good saw. Have to get a new air filter for it . Thanks for all your help:msp_biggrin: