Why do some or most high end chainsaws do not have a purge bulb?

[Macky Anthony]

So after an unsuccessful search, why don't some chainsaws have a primer bulb? Is it because of the bigger displacement not needing to have one? Thank you in advance.

 

[SEAM]

A primer bulb is not really needed on any engine larger than 35 cc or so, it makes starting easier (faster) but most engines will also start without operating the bulb... I usually bypass them when they break.

 

[old-cat]

Primer bulbs are for wooses like me! When ya get old and feeble

 

[sawfun]

Most what I would call, high end, saws do not have primer/purge bulbs. My 044's up through my 880 do not. My 372 and 395 do not either. Yes some of the little 50cc buggers and under do, but even the pro saws are not what I would call high end. I sure do not consider my 346 high end, just a modern 50cc pro saw.

 

[CR888]

l would like primers on some of my larger saws. l know many don't care for them ect but the op makes a good point as smaller saws are usually easier to start in the first place. Some of my 60+cc saws if not user for sometime take a good dozen pulls to be running.

 

[SEAM]

Just squirt some fuel on the air cleaner or into to the carb bore...
...and smaller saws are not easier to start - easier to pull, yes, but not easier to start.

 

[Pud]

Larger saws have a stronger pulse for the fuel pump

 

[pioneerguy600]

Just one more fuel related thing to rot out and cause air leak/lean conditions. It was the consumer/homeowner series of saws that started the purge bulb madness. Cheap disposable saws that would not be maintained by their owners so no great loss when they lean seized. I now have a Efco made,John Deere badged CS56 apart here,it has a purge bulb that has been leaking for some time, the piston is badly scored from lean run condition with the H needle set 2.5 turns out.
A well maintained,properly tuned saw does not need a purge bulb to start properly, the purge bulbs work good when everything is new but cause grief once they deteriorate.

 

[Chris-PA]

It's for purging air from the lines. A saw that is used professionally will be operated by someone more used to starting saws, and run more often, so it has less need for one.

 

[Whitespider]

I usually bypass them when they break.

What's the best way to do that??
Both my Stihl weed whip and leaf blower have 'em, and I'm tired of replacin' 'em.
And... how do ya' start 'em without... just pull a few more times??
*

 

[SEAM]

Depends on the carb/primer combination. If the bulb is part of the carburetor you can block the port going to the primer or the complete bulb socket using a piece of diaphragm material. If it is a separate primer drawing fuel through the carb via a hose and returning priming fuel to the tank via a second hose, the hose itself or the connector on the carb can be plugged. You need to make sure the carburetor still can draw fuel from the tank with the primer deactivated.
And yes, a few more pulls (or a few drops of fuel on the air cleaner) will be needed to start the primerless engine.

On carburetors with choke shutters (as part of the air cleaner box) removing the air cleaner lid and fully closing the carb bore with your thumb instead of using the choke will make starting a lot easier.

Another way to deactivate the primer is by installing a new one and never ever touching the sucker.... it'll last forever in that case.

 

[Whitespider]

Depends on the carb/primer combination. If the bulb is part of the carburetor you can block the port going to the primer...

They're both mounted on the carb like the picture below.
The originals lasted a good 10 years or so... I can't get two years out'a the replacements.
So you're sayin' I can block-off the passage that's inside the bulb... or am I not quite understanding??
I've never had either carb dissembled so I'm not 100% sure where that passage even goes... but I'm assuming the fuel supply side of the diaphragm.

 

[LegDeLimber]

You can plug the holes in that metering cover.
But just understand that it's like trying to dope over a hole in a leaky gas tank.
Stuff doesn't stick worth a hoot and especially so IF you're running corn-gas.

But of course, The best thing to do is find another cover without the punch bubble design.
Yeah, I know....easier said than done, when damn near all of the other carbs have this affliction too.

====
The external bubble setup is easiest to rid of the bubble scourge.
Clean, crimp and solder the appropriate nipple

But you will also have to close that stupid hole in the choke plate.
Otherwise you'll tear up the recoil from trying to get the fuel pulled
up for a cold start.

 

[Whitespider]

The "choke plate" on these is just a piece of plastic in the air cleaner assembly that slides in front of the carb opening... but I get the idea.
*

 

[dougand3]

For that trimmer carb, I'd go on fleabay and get 10 bulbs for $3-4.

 

[bikemike]

A good tuned saw dont need added crap for it to run and start easy. If you run out of fuel and refill just the comp release and pull slow and light it will draw the fuel then pop off

 

[Chris_In_VT]

They put a purge bulb on the husky 3120 at one point. Biggest saw they make.

 

[mikefunaro]

Some thoughts:

Most of the smaller saws are redesigned more frequently than the larger saws. More recently redesigned saws have them than older saws. I have never had a purge bulb and non-purged version of the same saw. I forget to use them half the time anyway. It is one more thing to break, especially when they are not well protected. Ethanol rots everything. Not entirely sure it's a displacement thing though because my redmax backpack which is around 70 cc or whatever has a purge bulb. I use them when I remember.

 

[jd548esco]

i've only got one saw with a bulb that is the echo 450. it is the fastest starting saw i have.

the exho 530 and 590 don't have the bulb but they start all most as quickly.

i wonder if i can put a purge bulb on my 372XP??--LOL

 

[El Quachito]

I figured it was a gimmick for homeowners. I am not alone in my estimation as I can see. I don't use the thing anyways on my 460 Rancher. Compression release is also a laugher.