Carb adjustment question, for better starting

[Fish]

I run a 1/4" pitch, full chisel Stihl rs chain, with the drags knocked off,
a 22 tooth sprocket, and a 24" bar. I installed a cupholder on it too.
The chicks dig it. The secret though is the splitfire plugs and 218 octane
fuel, since I have kicked up the compression ratio that high, it pings real
bad with standard racing fuel.
I painted it orange and white too, so no one will steal it.

 

[Fish]

I almost forgot my top secret oil mix, a blend of Mobil one synthetic, marvel
mystery oil, and stabil, I cannot divulge the ratios.
Also run Stihl's synthetic bar oil, on my patented maglev bar/chain
cutting system, handling the liquid nitrogen can be a bit tricky.

 

[Fish]

As far as the specifics on the technical aspects, you will have to ask my
engineers, BWalker and Glens, as I cannot handle the Calculus involved,
and the space/time anomolies involving a chain moving that fast.

 

[Fish]

But I digress

 

[pbtree]

Sounds like one rocking wild thang!

 

[brent denny]

Do you use a tach or tune it by ear and also have you tried square filing?

 

[brent denny]

Fish, I cant believe you changed oils on me. You used to use a grapeseed/linseed mix with a dash of oregano and a bay leaf thrown in. You always told me to take the bay leaf out or it would cause carbon buildup on the finger ports. Jeez! Make up my mind.

 

[Fish]

The grapeseed mix is better for your heart, but too compete with the big boys
I had to rely on modern advances in saw technology.

Square filing is for pu {ooops}!
I still adjust by the color of the muffler, but I do not recommend that
for the average saw.

 

[brent denny]

:d

 

[Mange]

Thanks for all the responses so far. In reply to questions:

lostone - Yes, the Huskys can be set to high idle with no choke. I am actually following the exact same starting procedure as you are with your Stihls...choke, pull until hits (2-3 pulls usually), then no choke but set to fast idle. At this point I would expect 1 or 2 more pulls to start, but it takes a lot more.

tony marks - Yes, my 359 has all three adjustment screws, Hi, Low, and Idle.

Mange - After the saw kicks with choke on, I turn the choke off and set the saw to high idle. However, I always re-push in the decomp button before pulling again. Should I try without re-pushing in the decomp button?

I will check the spark plug gap first, and if that is correct I'll also try backing up the low speed screw 1/8 of a turn. Will 1/8 of a turn out on the low speed screw make the low speed richer or leaner?

Yes.

 

[glens]

I think mange is suggesting pulling it without the decompressor on because the higher compression will create more vacuum and draw the fuel quicker. Im sure someone will correct me if im wrong.

And why wouldn't they?

StumpThumper, I have a friend with one of the new 359s and it has been nothing but horribly problematic for him.  Being the only experience I've had with them outside a showroom (or box-store aisle) they're not showing a good track record for me.

Not using the decomp valve will probably make things worse rather than better.  The vacuum which gets relieved through the carburetor throat is created under and solely by the upward-moving piston.  The faster the piston is able to move upward, the greater the velocity will be through the carb.  If you're using full compression above the piston, it will move measurably slower against the compressing gases then it will while they're being vented.  I know, this is rocket science and is probably way more off-topic than all the other fine help you're getting in this thread today.

Glen

 

[brent denny]

That makes sense.

 

[Fish]

Would not the lower compression make for a harder start?

It sounds like the choke is not closing fully to me, but I am not familiar with
that particular saw.
Old fuel is another possibility.

 

[rupedoggy]

Notice the decompression valve and its close proximity to the spark plug. Notice also that when the piston travels downward it can suck air into the cylinder. Until closed these valves allow passage both directions. The additional air can cause a leaner mix, near the plug, and when it is cold you need rich not lean. I also agree with Fish that more compression is better for starting. A normal person should have no trouble generating enough speed to start that saw, regardless of decompression valve position. Mike

 

[glens]

In that case, I'd suggest holding your hand over the muffler outlet as well.  Hahaha!

This model Husky, I thought, has the decomp down on the side of the cylinder.  In any event, anything above the piston will be replaced by fresh (properly-mixed?) fuel/air charge once the pressurized crankcase gets relieved by the open transfers above the piston.

Hopefully (I forget if this detail was mentioned) this wasn't a mail-order or box-store saw and it can be looked-over by a competent mechanic.

Glen

 

[Mange]

Have you thought about other benefits that can be made, by pulling without dekomp pressed?
I am not going to argue with any one about this, said my 2cents that is all.

I m not saying that he never use it, just try once. No throw start, just a normal pull in correct manner.

Please post result.

Mange

 

[brent denny]

Althought I can see where glens vacuum theory seems logical, I have tried starting two different saws I own with or without the decompressor and they will start easier without the decompressor every time.

 

[StumpThumper]

glens, does your friend have one of the new E-tech 359s with the cat. converter? If he has a green gas cap he has one with a cat converter. I've heard of problems with that model of the 359. Mine does NOT have a cat converter and everything I've heard about the non-cat model has been positive. Anyway, I will probably be running the saw this weekend, I'll post results. Thanks for everyone's insight so far!

 

[glens]

Yep, it's the green-cap model.

If you're getting a pop after a couple of initial pulls (and you must be if the decomp resets) I can't understand why you'd not get another afterward and why that one wouldn't stoke it up to make some steam.

I really wouldn't **** with it too much until it can be looked-at where you bought it if that's feasible.  Otherwise, caveat emptor (learned that when Greg Brady bought that convertible).

There have been some good suggestions so far.  If it's not one of the simple ones, it could be something not quite right in the carburetor; either the fuel pump diaphragm has some foreign material preventing it from pumping properly at low (cranking) RPM or the impulse hose driving it is leaking.  Maybe something like that...

You did say it works and makes good power otherwise, right?

Best wishes,
Glen

 

[glens]

I hate to edit a post after the time limit passes where it's indicated in the post that it's been edited.

This fuel-pumping aspect, which I suspect is part of the problem (after the plug/timing is checked, of course), would also be aggravated by a slower-spinning engine, such as would be the case with the decomp out of service as opposed to the freer-spinning less-compressing unit.

I don't deny that more compression would be desirable in terms of getting a more solid first pop, but the weaker pop should still be sufficient and with it, every moving part from the shoulder to the flywheel will last longer.  Unquestionably.

Glen