026 Pro Cutting Out w Brake

[logbutcher]

The "almost perfect saw" is behaving like a bad boy.

This Stihl 026 Pro with a high / low adjustable carb, clean filter, new plug, clean high test mix, and sharp chain is cutting out/stalling when pulling the chain brake off. Unless I goose it slightly while letting the brake go, it will stall. All adjustments seem to be normal when warm.
I've tried increasing the idle but don't want the chain to creep.

Explanation is in order. I never used a chain brake under normal use before training in GOL (Game of Logging) and CPL ( Certiied Pro Logger). Besides full PPE (Personal Protective Equipment), I follow guidelines in that program that make safety sense such as chain brake on when moving more than a couple of steps with the saw idling. It works especially in thick blowdowns and brush.( No, I don't belay on the ground.....yet. )  The training also recommends always starting with the brake on. Use of the brake now is second nature in my cutting, clearing, bucking, TSI. Long winded here....

So, what would cause the engine to die when 'pulling' the chain brake off ? Anything specific that I can adjust, check ?

[jokers]

Try richening your lo speed needle.

Russ

[logbutcher]

Already done the lo to rich and richer.
" Can't be too rich or too thin."  

[Kevin]

It may also be restricted fuel anywhere from the vent to the carb or leaky carb gaskets at the intake port.

[Rocky_J]

Actually Russ, I was thinking just the opposite. A slightly rich low end adjustment will cause a saw to load up with fuel while idling and then stall out when the throttle is hit. I read a good way to check this on the 'other' forum- let your saw idle for a few minutes and then turn it upside-down. If the low speed jet is too rich, it will stall from all the extra fuel in the bottom of the motor getting dumped into the cylinder.

[logbutcher]

Will do both: upside down check, vent hose, gaskets.
Neat ideas as usual !  Thx guys.

BTW: are Brian and Russ twins?  Curious minds want to know ...     Dopelganger or something?

[Rocky_J]

No, Russ and I are not twins. I'm much smarter and better looking than him.

[tony_marks]

  just curious .. do u start it with the brake on... i know they saythats safer and everything . but i dont do that.. never have..
 do u guys all start u saws with brake on.. some of mine would be a bear to start that way.. just curious..
  rocky and joker ,twins.. now thats a good way to get both ofum mad atchu.

[logbutcher]

Lunch break.

Contest idea: who's the best looking online. Virtual cheesecake. Maybe even : The Great Nude Chainsaw Finale.
The "how do I look in chaps, gloves, helmet...without anything else" contest .      We could even have a special forum.

Tony: the " brake on " method is  protection from the infamous "drop start" that we all (past tense) have used. Many many slicings from a high torque saw at rev speed hitting soft flesh w the drop start documented. The official GOL/CLP start is w brake on, then start it with the saw between the thighs (no comments here kids !     ). You have complete control of the reving saw. Alternative is to start w your tiny boot in the handle on the ground...not always possible on tough terrain.
Brake on when moving anywhere w a running saw, or shut it down  Later is usually impractical for most of us. No one of us has fallen when walking/running/ambling w the saw running.. ...right ? .

BTW: changed the lo needle to slightly rich. No effect right up or upside down. Gaskets 'seem' to be OK. Vent open.
Still trying. Thx. Tak tak.

[Kevin]

Maybe a little carb cleaning?

[oldsaw-addict]

If you cant figure it out, then I would suggest taking it to the dealer for service. It sounds to me like the issue is something to do with the fuel mixture needles, maybe the H is too rich or lean, when you go to rev it up, does the saw just stall the instant you go to rev it or does it get to slightly higher rpms then stall? This should help me get an idea of how I could help.

[firtol88]

Lunch break.

Contest idea: who's the best looking online. Virtual cheesecake. Maybe even : The Great Nude Chainsaw Finale.
The "how do I look in chaps, gloves, helmet...without anything else" contest .      We could even have a special forum.

That sounds like the single worst idea I have heard in quite some time. Don't know about you but the [size=52]LAST[/size] thing I want to see is a man's hairy arse.

[oldsaw-addict]

Amen to that. I dont want to see a mans hairy backside any more than anyone else here does.

[jokers]

Actually Brian and I are twins, although he is the smarter and more handsome evil twin.  

Brian,
I follow your logic but I believe that Logbutcher stated that the saw dies if he DOESN`T gas it when releasing the brake. My line of thinking is that he is masking an ultra lean condition by feeding the saw off the hi speed circuit. Might also be a crank seal.

Russ

[logbutcher]

"...masking an ultra lean condition by feeding the saw off the hi speed circuit. Might also be a crank seal. " Jokers
Some explanation and solution here?
Saw runs super--accelerates smoothly up to WOT, idles fine.
Only problem when 'pulling' the brake off for continued cutting. I do this a lot in blowdown clearing. End result to bring brush and trunks to ground for moving.  The saw then will stall at idle while the brake is being pulled 'off' unless goosed. All when well warmed up. Still trying and thx for the advice.


Whew: some of you people are sensitive about hair !!!   ::)This is a "chainsaw" forum after all. We're talking "nude" here, not "backsides" IMHO.     And you there firtol88, you're first. Runway will be on 31 Dec, 2004, 10th Mountain Division Winter Sports Center, Fort Kent, Maine. RSVP.

[Stan]

That sounds like the single worst idea I have heard in quite some time. Don't know about you but the [size=52]LAST[/size] thing I want to see is a man's hairy arse.

Some of us are a bit further along the evolutionary path, and don't have hairy butts.  

[SasquatchMan]

Speak for yourself Stan.  I grow better hair uncultivated on my butt than you can grow cultivated on your head.

Am I misunderstanding something here - what on earth does disengaging the brake have to do with the running of the saw.  If the saw runs with the brake on, clicking it off shouldn't affect the saw - unless some internal brake component is malfuncioning?  I know the brake in my MS290 is "internal"... could the brake be affecting the clutch?  That would stall er out in a hurry.

[Stan]

Speak for yourself Stan.  I grow better hair uncultivated on my butt than you can grow cultivated on your head.

Then you have chosen your handle well. When he takes the brake off, the saw stalls because the load has been suddenly removed. I don't know why that makes it stall, just that it does. Sometimes when I take my foot off the brake on my wife's van and don't get on the gas, it stumbles.

[SasquatchMan]

When the brake is on at idle, the clutch is disengaged.  When you remove the brake, the clutch remains disengaged, if all things are working right.  

So where's the load differential?  There isn't one.  Which is why I can't figure this as a mix issue, but rather as a mechanical one.

[Rocky_J]

If the chain is trying to spin when the saw is at idle, then either the idle is too high or else the saw has a broken clutch spring.

[incognitive]

I'm prettier than either Rocky or Jokers, and they can attest to that since they recently, finally, got to see me.  I haven't seen a pic of Jokers, but anybody that kicks sand like he does has to be mad about the way he looks.  (shh!, at least for a little while, ok?)

butcher, this sort of problem is exactly the type of stuff that interests me.  I'd like a little more concise detail, particularly regarding:

• are you saying that merely the act of releasing the brake causes the engine to stumble?
  
• when the saw is idling without the brake and at the moment you engage the brake is there any change whatsoever in the way the saw's operating other than now the clutch drum is locked?
  
• assuming the first point is true, does it matter in what manner the brake is released?
  • saw sitting on ground
    
  • saw in the air, left hand removed from front handgrip to pull back on guard while supporting saw only by rear handle
    
  • same, but also supporting saw against thigh
    
  • saw in the air, left thumb supporting front handgrip while pulling back on guard with left finger(s) (essentially the same as item above while supporting saw on thigh)
    
  • saw in the air, supported by front handgrip in left hand, brake release by right hand
  I guess what I'm getting at is, if the mere act of releasing the brake is instigating the stumble, there must be a marginal electrical connection (least likely) or some physical property (defect) of the saw which is being particularly influenced by the action.  I can't figure what it might be though, that wouldn't also be a factor in almost any situation the saw would be at some point during normal use.  
  
  If it were, say, an isolation bushing being out and allowing the pulse hose to be pinched off against the rear handle as you pull the guard back with your left hand while holding the rear handle in your right or something.  Or maybe a cracked pulse hose being opened momentarily during the same action.  Why wouldn't you ever run into it at some point during normal use?
  
  Try the various methods of brake release and report back any differences in response.
  
  I highly suspect it's not got anything to do with jet or metering valve settings inside the carb.  Rather some wire or hose or boot being influenced in a negative way.

[logbutcher]

OK, it is "hoosier", as in : " hoosier moma, hoosier fatha" ?

Incog has given some serious details needed. Will do during tomoro's cutting.
Some prelim replies:
Yes, the engine slows to stall in the act of releasing the brake in a slight down angle close to the right thigh.
Yes, there is a slight "stumble" in the engine when engaging the brake with a flick of my forearm downward.
I will try all five of the saw positions when engaging/releasing the brake.
And what is a pulse hose ? Where to check ?  
Interesting eval of a problem Herr Hoosier. Have you rock or ice climbed in another life ? Analogous problem solving en routes.
Thx all........very invaluable info !!    

[incognitive]

The (im)pulse hose connects to the crankcase and drives the fuel pump diaphragm on the carburetor.  If it's marginal, it might, when flexed, cause poor fuel pressure and/or directly allow air into the crankcase; both resulting in a lean condition to various degrees.  Such a problem may be more pronounced at idle where there isn't enough rotational energy to carry through a temporary glitch.  I should think it would be evident either way, though.

Hoosier like in resident of Indiana.  And no, not an ice climber, though I had a good friend out in Colorado who was.

[Jeff]

Just a reminder fellas. This is the Forestry Forum. We have a record of being A friendly family site. We are listed several places as an educational resource. Lets stay on the tasteful side of things. Nothing here I would delete or edit, just a reminder for the new guys though, The forestry forum's chainsaw forum is your kinder gentler chainsaw forum. A chainsaw forum for EVERY one.

O.K. I had my say. Go ahead and shave or what ever it was you were all doing.

[jokers]

.... The forestry forum's chainsaw forum is your kinder gentler chainsaw forum. A chainsaw forum for EVERY one....

A chainsaw nut safe haven.  

Jeff and Kevin have done an exemplary job of keeping this forum laid back and friendly, it`s a pleasure to come here and kick back.

Russ

[Minnesota_boy]

When the brake is on, it puts a side load on the crankshaft.  When it is released, that load is suddenly no longer there.  I'd be looking for a seal leak or a crankshaft bearing that has too much play that makes the seal leak.

[tony_marks]

  i still cant sell myself on starting a saw with brake on..
thats a nice safty feature while using the saw ,,but as ive stated ,,most of mine dont even want to start,, with brake engaged..jmo
ps been doing it this way since long before they had brakes onum..i mite add ,,u new fellas at this game need to follow the suggested method of cranking the things.. dont want noboidy getting hurt because of something i said..

[Mark M]

I'm kinda like you Tony, I just don't like to hear it start up under full load, even if it is only for a second. The only time I use my brake is when I'm walking through the woods (which is almost never cause we don't have any trees)! I also use it if I'm climbing over something or if there is a chance I could fall.

Mark

[logbutcher]

Back to the naughty 026 problems. Been out of town on the company's business.

Incog's analysis and direction are on the money---it stalls/cuts out/dies only after warming up for a few WOT cuts in all of your suggested positions. Then hard starting at idle, I need to use the cold start switch position, not the full choke cold start.
Frankly, the impulse hose, and the bearings are beyond my skills (got to know what you cannot do). How would I begin to check those items out without a manual or solid 2-stroke chainsaw experience? Anything simple ?  
The mystery is that the 026 runs perfectly cutting at WOT.
Guess it will need to be brought to the Stihl man. Maybe spanked  .

Chain brake thing: after many years of not bothering to use it, after many slips/falls/stumbles/slices with saws idling, the brake on technique makes sense. In fact Stihl and Husky strongly recommend the use at all times when not cutting. It is engineered for normal use, they say. Or, shut the saw down when moving. No I'm not a "new" guy, just an old hacker that was educated by the pros in the Game of Logging training. I go back to firing range days in OCS stuff (insert violins here) . Those DI's were tough in all ways with handling firearms, ordinance, explosives. It took us hotshots years to figure out that they were correct.
Yet, there are far fewer accidents and deaths from handling firearms and ordinance (crimes excluded) than chainsaws.
So, I now use ALL of the CPL training techniques all of the time (well, Pinocchio).
Thanks all !!!!!!!!

[Kevin]

What's WOT, wide open throttle?
If that's the case I would be looking at an air leak.
Crankcase or intake manifold.

[oldsaw-addict]

Possibly crankshaft seal at the clutch side bearing is leaking, may be the intake manifold or perhaps the crankcase/cylinder base is not sealed tightly and is sucking air in. there is a trick to find the leak, I use WD40, spray it on the crank seal with the engine running if you get better performance you've found the leak, try checking the cylinder base screws that hold the cyl to crankcase, they may be loose, and make sure the intake  boot/manifold is not loose either. any one or combonation of things from the list above can cause the problems you've described. try it out and see, I'd like to know how it goes.

[logbutcher]

Can't figure out the "quote" thing here. But--
O-A: Nice idea w the WD40. Also tightening bolts/screws IS something I can do    . Without a schematic of the saw where are those bolts and exactly where are the crankshaft seals, intake boot, manifold ? I'll try to get a schematic from the dealer. Maybe one of you could use your skills in the forum to show a diagram or illustration.
BTW: how do you do the "quote" thing ?
Sorry Kevin, "WOT" is "wide open throttle".
Got to stop using these TLA's (Three Letter Acronyms). With all the tech terms here, I've got to have some secret words .
THX ALL !!  
PS Spring has come --over 60 F today...then the black flies (the real Maine state bird) . They'll enter our lives when moving water reaches 48 F.

[oldsaw-addict]

The cylinder bolts are located on the 4 corners of the cylinder, if you take the top cover which is plastic off, there should be 2 or 4 holes that go all the way down to the base of the cylinder, they are the ones you need to check, the screws I mentioned earlier are at the bottom of those holes, they're on the very outside edge of the cylinder and should be fairly easy to check. Intake manifolds and carb boots are to the best of my knowledge the same thing, one is a rubber boot that connects the carb to the engine, the other is a plastic or metal piece that does the same thing, they are in between the carb and the cylinder. if you have a rubber boot, check for holes, rips, and tears in it, if there are any of the above issues with the boot, replace it. Crankshaft seals are on the outside of the bearings which are pressed into the crankcase, you'll have to remove the drive sprocket and clutch assembly to check the clutch side seal. If you need further clarification I'll help as best I can.

[oldsaw-addict]

Oh  yeah I forgot to mention, I use WD40 for the leak testing because it is a lubricant and will burn in the cylinder. Just be VERY careful when you spray the WD40 at the seals, if you spray the muffler you may get a mini bonfire/flamethrower.

[Kevin]

It will look similar to this Walbro WT-603 at http://www.petrolscooters.co.uk/tuning.htm

[jokers]

I'm prettier than either Rocky or Jokers,.......

Aye, that you are! I`ll bet you would have been popular on a six month cruise.    My evil twin and I have to be satisfied with simply being vile and repulsive.

Russ

[incognitive]

My evil twin and I have to be satisfied with simply being vile and repulsive.

Russ

I have to find a way to do that without getting booted!

[logbutcher]

Update on the 026 saga.
The Stihl tech that sold me the saw says that the 026/260 is not "meant to be idled or stopped with the brake on."   That that model line is high compression and needs to run and not idled with or without the brake. That the brake will over heat the engine if used for any amount of time.
And, "...that since the saw is fairly new, it needs to be broken in for it to 'loosen up' " .
For you full time users, do any of you use the brake in normal use : starting, moving with the saw running, or throwing brush w it running  ?
The Stihl guy says that if I'm stopping for more than 30 seconds, to shut it down and re-start. Possible, but I've gotten used to moving even to the other side of a tree w the chain brake on.
Do I need to change my work habits with the 026 that I did w the old, reliable 028 ?  The 028 would sit for 5 minutes, sometimes more w the brake on with no problems.
Let's hear some more experienced options.
The leak checks continue anyhow with all of your advice.

[Kevin]

Is it just stalling with the brake engaged or at idle without the brake as well?

[incognitive]

I'd say that either we, or he didn't get enough information, or that he's blowing smoke up your behind.  If the saw is an "026 Pro with a high / low adjustable carb" as you originally said, how is it so new it's not loosened up yet?  Have you put a couple gallons of fuel through it?  If so, it's there.  If not, it should still idle through a whole tank of gas if it's not got any leaks or mis-adjustment.

The only way I can see a brake heating the engine is if the clutch is attempting engagement and that clutch drum would be smokin'.

I don't habitually use my brake but I do use it some and on neither my 036 or 066 have I ever had a lick of problem.  I'd as soon shut the saw off if I'm traveling through the woods as I'd rather have the chain freewheel as it snags on stuff.  I'd also like it to spin out of the way rather than be stationary in the event I might stumble onto it or something.

At any rate, 30 seconds idling is just too short a time to cause any kind of problem on a healthy saw.

Tell us a little more about how you came to own that saw.

[oldsaw-addict]

I never have had a saw that has problems running with the chainbrake on, at idle that is. I'm just getting into the habit of setting the brake when I set the saw down so I'm on the right foot now, getting safer now.

[jokers]

Logbutcher,

I have to agree with Incognitive(just don`t tell him) that the "tech" you saw, made up that whole bit about not being broken in and the 026 not being able to idle because of high compression. I can`t even begine to imagine the hours that some of my 026`s have idled, even with the brake on. I even observed my dad with a brand new 260Pro idle through about a tank of gas when he was chipping and then got sidetracked and left the saw running on the ground. What your tech said, just ain`t so!

I`d like to have your saw here to find out what`s really wrong with it.

If someone can tell me how to do it, I will post an 026 workshop manual pdf. here to help you out. You`re obviously on your own when it comes to local service.

Russ

[Rocky_J]

.... What your tech said, just ain`t so!
....
If someone can tell me how to do it, I will post an 026 workshop manual pdf. here to help you out. You`re obviously on your own when it comes to local service.

This last sentence is exactly why I finally decided to try a Husky after buying Stihls all my life. I have absolutely no local Husky dealers, but it isn't like the local Stihl dealers are much better. I haven't paid a shop to fix a saw for me in 8 years and don't plan on doing so anytime in the future. Stihl parts are expensive locally, Husky parts are cheap online but I have to pay shipping. Price is a wash but with Husky I get the stuff delivered to my door.

Almost all the Stihl techs I've met will make up stuff in order to sound like they know what they are talking about. The more I learned about saws, the more I realized how little most shop mechanics know. There are a few good ones but most are as incompetent as most 'tree services'.

[logbutcher]

We're on the same page: idling saws w or wo brake are normal.
Generous    of Russ to offer the workshop manual !!. Is there a site for them ? Downloading in .pdf is long, but doable w your scanner. Maybe 1/2 six pack.
Must be an easier way.
Still can't figure out exactly what and where the pulse hose is, the crankcase seals (to test leakage w WD-40). Anyone have schematic diagrams  to put in a post ?
Ah, the ignorance of it all     .
What a forum............!!!!!!!!!!!!!!!!!!!!

[Ianab]

Hi Log

I'm not a chainsaw expert.. but simple explanations I can do
On one side of your saw you have the recoil starter cord, on the other you have the clutch and chain sprocket. These are on each end of the crankshaft. On each end of the crankshaft inside these bits are the bearings and seals. If these seals are worn out then air can leak into the crankcase, bypassing the carby and totally mucking up the idle settings. I guess that spraying some wd40 on the seals would stop them leaking air temporarily and be usefull for faultfinding. I'm sure the others will pull me up if this is wrong  

Ian

[Minnesota_boy]

Ian,
The WD-40 is a nice light flamablle oil that can be sucked in past leaking seals.  This additional flamable liquid will cause the saw engine to speed up if the seal is leaking.

Logbutcher,
On many saw engines, the impulse line is built into the carburetor mount.  There is no impulse line to find.

[Ianab]

Thanks Minnesota

Either way, spraying wd40 on the seals will have no effect if they are good. If you spray and something changes.. then the seals are leaking.

A usefull test

Ian

[incognitive]

Here's a small part of page 11 from the 026 parts PDF.  Note item 23.


The hose attaches to the carburetor mount and to a nipple near the cylinder base.  It will be to the clutch side and a little below the intake boot.  The tests I was describing earlier were to determine if the stumble upon brake disengagement would disappear if there were no relative movement between the engine and handles.  I was thinking that by grabbing the brake release, the engine was moving back to the handle far enough to flex the impulse hose, thus opening a crack (or maybe one in the intake boot ["manifold" in the documentation]).  I don't think crank seals would affect what you're describing if it only happens when changing the brake status.

So logbutcher, did you buy a rebuilt saw from this guy or what?  If so, it's possible the top end's still tight and needs broke-in while the bottom end's (too?) loose, and/or rubber parts need replacement.  Let us know.

[jokers]

The impulse hose actually attaches to a nipple on the carb in the case of the 026.

Nice pic G but why so stingy? !

Russ

[incognitive]

Tied hands, my friend.

[logbutcher]

WHAT A CREW[/b] !!!!!!!

[logbutcher]

FLASH:
Update on the 026 Pro saga.
With all the super tech advice, no leak was found by me. Hose(s) look fine, unable to really check the AV mounts, WD-40 0n the seals did nothing ( no flame thrower    .
Thx for the assist: Incog, Mr. Marmite NZ, the Rocky and Joker twins, oldsaw, ianab, et al. .
The selling Stihl dealer has gone to another shop--Husky ! He still does not want to repair the saw he sold me since he feels that the saw should not be idled for any amount of time or certainly not idled w the brake on. It's gone thru about 12 tankfuls in a month or so. He said that the brake is only for "emergencies". We don't agree.  
Honest guy however, he's going to take the saw back for what I paid. Fair, ethical....the Maine way. No fights here.
I've since cut for a couple of hours with the 346XP with a logger neighbor. You 346 fanatics are correct: NICE TOOL !!   . ( And, you are fanatics )
I'm getting that tool.