Author Topic: Echo 590  (Read 3533 times)

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Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #20 on: April 26, 2014, 05:42:03 am »
Hi Joe,
Be careful with the B12.  That stuff is known to melt the check valves inside the high speed nozzle. Walbro HDA-268 doesnt have a replaceable nozzle fwiw so if you melt it you will need to make some other arrangements.  I may be telling you something you already know?  There are two kinds of check valves in the H side of the walbro carbs.  i. is a capillary seal type and ii. is a mechanical seal.  The reason that the check valve is needed is to keep the baro pressure from getting down inside the metering chamber of the carb.  Symptoms of a leaker is an idle mixture that wont tune.  One moment lean the next rich and so on.  Wont accelerate from an idle (bog).

edit:  taken from bob's post above.     

...  wanted to post this very informative link, (the best i have found)..... for basic carby operation, so folks can get a visual understanding of what you are referring to.......  http://helifreak.com/showthread.php?t=326599


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Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #21 on: April 26, 2014, 06:15:50 am »
Hi Joe,
Be careful with the B12.  That stuff is known to melt the check valves inside the high speed nozzle. Walbro HDA-268 doesnt have a replaceable nozzle fwiw so if you melt it you will need to make some other arrangements.  I may be telling you something you already know?  There are two kinds of check valves in the H side of the walbro carbs.  i. is a capillary seal type and ii. is a mechanical seal.  The reason that the check valve is needed is to keep the baro pressure from getting down inside the metering chamber of the carb.  Symptoms of a leaker is an idle mixture that wont tune.  One moment lean the next rich and so on.  Wont accelerate from an idle (bog).

The black plastic 'scoop' that is in the air filter is a spit back plate.  In a piston ported engine, the piston skirt closes off the intake.  When this happens any speed that has accumulated in the intake track slams into the skirt.  Air itself doesnt really have a whole lot of impact, but once mixed with fuel is heavy and thick.  The inertia of the fuel bounces off the skirt and splashes out into the air filter.  The spit back plate is there to catch this and keep it out of the atmosphere. 

Thanks for the pics on the throttle plate adjustment.  I could see where this would make a big difference on the high speed hit.       

heya bob....
thanks for the heads up on the epoxy.  glad you mentioned this.  applied the epoxy to fill the extra holes i drilled throttle butterfly, only for testing purposes.  would not recommend using it for long term operation.  do not know for certain, if stick epoxy can resist the effect of fuel.  (however, for a more permanent fix, marinetex, seems to work pretty well for this).

think you are spot on about the check valve(s) giving me the fits.  could this problem be caused by the added pressure drop the extra air hole(s) have over the high speed check valve...... keeping it open, when it should be closed at idle speed?

the black plastic "scoop":  read somewhere that the intake pulses resonate through the intake tract, and fuel gets metered multiple times during each piston stroke, as air gets being bounced back and forth through the carb.

good stuff bob!

regards
-joe


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Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #22 on: April 26, 2014, 08:07:49 am »
The other thing that crossed my mind about transition fuel delivery is the 'idle' holes which are drilled into the throat of the carb below the welsh plug.  Usually there are 3.  The 1st one should be visible from the throat with the plate closed looking into the throttle bore.  #2 is directly beneath the plate, at the cutout, with the plate closed.  #3 is on the venturi side of the plate. 

Im trying to post the drawings for the 268, the hole sizes are in the narrative.  I dont know how much larger I would go with those holes unless you want to start running alcohol instead of gas.     

***Keeps saying the file is too large, let me try something else***
 

tried measuring the idle progression holes before you posted the schematic.  (+1 on the schematic by the way!  i have to figure out how to enlarge the schematic so i can actually read it).   the only thing i have here to measure holes this small is a ancient spark plug wire guage.  (in a pinch, putting a round toothpick in a small hole, rotating it, so it leaves an indent mark, and then using dial calipers to measure the pick gets me close).

i really don't want to enlarge any of these idle holes.  have jet drills, but will surely end up making a mess of them.

at this point, my single hole is centered even with the high speed discharge in height.  think that enlarging the indent on the throttle butterfly, may be a better option than using the present drilled hole location.  probably would pull more fuel out of the idle holes at idle speed.

will buy a few extra butterflies to test this idea out further.  want to keep this simple, and cheap.

i'd give up up this in a second, and revert to getting a new stock throttle butterfly, if it were not for the fact that the change in carb response was so good with the additional drilled holes.  i
--------------------------------------------
for me to post pics, it has turned into a three computer process.  work computer to download camera pics; then transfer to memory stick; put into home desktop pc to shrink; then laptop with internet connection to put on site.  oh well.
--------------------------

regards
-joe
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Offline sharkey

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Re: cs-590 wolf review. bone stock.
« Reply #23 on: April 30, 2014, 06:58:37 pm »
I ran a few tanks through my 600p this weekend.  The porting has it occasionally pinging off the limiter so will switch out to a larger rim or move to a longer bar.  The saw ran pretty good all things considered.  Most noteable was fuel consumption.  Burned 30% more fuel with the larger carb.  To do a fair size Maple, limbing and bucking, I was burning almost a whole tank.   

The diagrams got kinda fuzzy when they were re-sized to post.  If you would like me to email the originals, send me an email address via pm.

Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #24 on: May 01, 2014, 06:24:04 pm »
nice, sounds like time well spent! 

curious, do you think the 30% increase in fuel consumption, was mainly from the larger venturi carby?......or from the saw now being able to make more power (and now spending more time), in a higher rpm range?

going to be purchasing a longer guide bar for mine soon, how long of a bar will you be getting?

-joe
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Offline sharkey

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Re: cs-590 wolf review. bone stock.
« Reply #25 on: May 02, 2014, 09:09:47 pm »
Im thinking about changing out the ignition.  Echo offers both limited and non limited magnetos on their engines, hope to come up with something w/o spending alot of $.  The 'digital' type seem to be the limited ones but the amount of advance is also a consideration.  Current timing is; 11 degrees BTDC at 3k rpm, then 32 degrees BTDC at 8k rpm, which then drops one degree and stays at 31 degrees BTDC at 12k rpm.  13500 +/- 200 seems to be the magic number on the limiter.     

If the engine is making more power. it should use some more fuel.  It just seemed like I was really going through the gas on that one tree.  We are clearing a piece of property and Ive cut down about 30 fair sized hardwood trees there so far.  The bars we have are 24, 28 and 32 inch D176 mount so will keep monkeying around till I find something I like.  I really wanted to keep this saw light though and was wanting to keep the 20 inch bar.  I switched to an 8pin rim to see how it affects the limiter.

If your trying to find one saw to handle most of what you will encounter, the 590/600 should be a winner.  My problem is, as I get older, Im looking for a saw to be light weight.  I dont want all the weight that the bigger saws come with but I do want the chain speed and power.  Maybe I should set this little hot rod up with .325 skip on a 28 inch bar? 

Below is an attachment with some additional engine info.

 

Offline aclarke

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Re: cs-590 wolf review. bone stock.
« Reply #26 on: May 02, 2014, 11:48:23 pm »
Don't think you're gonna make any more power with an unlimited coil unless it's hitting the limiter in the cut now which I'd unlikely
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Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #27 on: May 02, 2014, 11:54:04 pm »
happy so far with my saw purchase.  very smooth cutting. 

how does the echo limiter work?.......does it drop every other spark? ....or is it dropping all the sparks at a preset rpm?

did not know the bar pattern, thanks.  will look into those options.  echo has a 27 inch bar available, maybe will give that one a go.  like my little 340 for the smaller diameter stuff, bought the 590 mainly for some medium diameter trees that will need to come down soon.  at the time being, don't foresee needing anything larger in cc than this 590, if it can pull a longer bar.

i don't have much time, but usually am in no hurry when cutting.  chain speed does not mean all that much to me.   way i look at it is, the sawing is the easy part.  know that when i'm tired, easier for accidents to happen.

regards
-joe









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Offline 660magnum

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Re: cs-590 wolf review. bone stock.
« Reply #28 on: May 03, 2014, 01:19:04 am »
Most of the coil limiters have an opposing wound smaller coil in them that bucks the main coil at the higher rpms, causing the spark to get weak. It will oscillate around as the rpm changes and give you the impression that it is every other spark?
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Offline 1manband

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Re: cs-590 wolf review. bone stock.
« Reply #29 on: May 03, 2014, 07:55:31 am »
Most of the coil limiters have an opposing wound smaller coil in them that bucks the main coil at the higher rpms, causing the spark to get weak. It will oscillate around as the rpm changes and give you the impression that it is every other spark?

where is the stored energy going when the spark is dropped?  is the spark energy dropped stressing (heating up) the extra smaller coil during the 'drop', or going to ground somewhere else.

puzzling to me, electrical is not my thing.  maybe do have a handle on points and mags, but question my thoughts on these issues as well.  hahaha.

-joe
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