Caution on wot out of wood on new strato"s

[indiansprings]

Went to a tech update this week. Irregardless of brand, on the latest strato's you want them to warm up 30 to 45 seconds because of the longer piston skirts, want them to warm up evenly.

They warned us to advise customers never to run saws WOT out of the wood (no load) longer than 10 seconds or you can start damaging your saw, they hace tested other saws beside Stihl and the same results occurred.

So for those who like to hold them wot out of the wood for extended periods you are just setting yourself up for damage.

 

[hamish]

Whats changed over non strato saws?

That has been best practice for years.

 

[SawTroll]

Sounds perfectly normal to me - I don't get what the changes are? :msp_confused:

 

[indiansprings]

It has to do with heat transfer, most strato's irregardless of brand are using longer piston skirts and thinner crowns on the piston, they are taking longer for the whole piston to warm up, but the prolonged no load wot can cause excessive heat build up at the rpms all the new strato's are running due to being set lean at the respective factories to pass the EPA, makes sense in wood or load they are not cranking the 14k but much closer to 9/9500 in a cut, lots of difference.

 

[dl5205]

I don't EVER like to hold WOT out of the wood, But ya have to tune every now and then.

 

[tpope]

Thanks for the heads up. Never done that myself, but can see how some might.

 

[514mach1]

Thanks for the info... not that I keep it wide open for more than a second or two at most when not cutting. Sorry to be picky, but "irregardless" isn't a correct word. "Regardless" is.

 

[FATGUY]

not unreasonable.

 

[hamish]

It has to do with heat transfer, most strato's irregardless of brand are using longer piston skirts and thinner crowns on the piston, they are taking longer for the whole piston to warm up, but the prolonged no load wot can cause excessive heat build up at the rpms all the new strato's are running due to being set lean at the respective factories to pass the EPA, makes sense in wood or load they are not cranking the 14k but much closer to 9/9500 in a cut, lots of difference.

Having a bit of difficulty following this. Most saws run 12.5-14k WOT out of the cut and max power is usually in the 9-10k range, in this respect nothing has changed.

Anything to do with the fresh air travelling through the transfer ports, providing cooling?

Have been to many a service school and updates, have yet to see or read anything of the sort directly related to strato saws vs non strato saws.

I would like to know more, this place is a great place to share knowledge.

 

[Andyshine77]

I know strato's take a bit longer to warm up, likely do to all the cool fresh air traveling through the passages in the piston. Like indiansprings hinted at, it's likely a combination of many factors. Lean tunes, lean oil mix, the fuel itself, temperature and so on. I've also noticed more discoloration on the underside of the pistons in strato engines. I guess this means the piston gets hotter? or the temperature changes rapidly?

 

[hillwilliam]

not unreasonable.

I like that! To expand on the elegantly understated: 'Irregardless' is a real word, but it just doesn't make a helluvalotta sense, since it's a double negative. That's how my beerfuddled mind interprets the concise response, anyway.

 

[Justsaws]

Went to a tech update this week. Irregardless of brand, on the latest strato's you want them to warm up 30 to 45 seconds because of the longer piston skirts, want them to warm up evenly.

They warned us to advise customers never to run saws WOT out of the wood (no load) longer than 10 seconds or you can start damaging your saw, they hace tested other saws beside Stihl and the same results occurred.

So for those who like to hold them wot out of the wood for extended periods you are just setting yourself up for damage.

:hmm3grin2orange:

Yep, cannot blame the big E anymore since it's here to stay and has been here for ever so now it will be NLWOT.



They're gonna have to put a little light on the top of the saw that comes on when it is warm enough to use and maybe a little bell. They could consult Mattel and purchase the marketing rights to the EasyBake oven setup, little shelf on the side of the muffler for cupcakes and bacon, sweeeeeeet.

The other brand could go with Betty Crocker, when you smell tasty cookies you may use your saw, or Orvel Redenbaker, when the popcorn pops you may use your saw.

So is that advice in bold print in all the new manuals? or just a way to explain all the cold seizures into operator error.

 

[ropensaddle]

Wow

Sure am glad I own non stratos cause I never let off the trigger :hmm3grin2orange:

 

[mountainlake]

Having a bit of difficulty following this. Most saws run 12.5-14k WOT out of the cut and max power is usually in the 9-10k range, in this respect nothing has changed.

Anything to do with the fresh air travelling through the transfer ports, providing cooling?

Have been to many a service school and updates, have yet to see or read anything of the sort directly related to strato saws vs non strato saws.

I would like to know more, this place is a great place to share knowledge.

Right, every stocksaw now should be run 9000 to 10000 in the cut where the cutting speed is, plus all saws should be warmed up slow. No long hard cuts right away and tuning should be done warm for a couple of seconds. With these strato saws using way less fuel they might run hotter. Steve

 

[7sleeper]

Thanks for the info! :msp_thumbup:

Now one has to think about it. Obviously strato saws are running to cool and potential engine damage may occur. So to counter this effect all strato saws should be equiped with a cat muffler!

I only have one strato saw and that is a small homeowner model for cutting around in the garden. But I may have to change the carb settings a little bit.

7

 

[nmurph]

I like that! To expand on the elegantly understated: 'Irregardless' is a real word, but it just doesn't make a helluvalotta sense, since it's a double negative. That's how my beerfuddled mind interprets the concise response, anyway.

Irregardless is a word in the same sense that ain't is a word: it ain't a word irregardless of what you say.

 

[blsnelling]

No saw should be held WOT when cold. There has always been a risk of a cold seize. Once warmed up, I don't see the concern, although I never like to hold a saw WOT any longer than necessary. Perhaps this was a reminder, rather than a change.

 

[lambs]

Wow I don't know a soul who runs a saw that long before putting it in the wood. But I might start doing it now.

 

[imagineero]

I've got a few 441 crm's and they are cold hearted #####es. They turn over easy, but they all die when you give them some throttle and need to be re-started. The start procedure isn't so straight forward as you might think. On non M saws I would usually go full choke, pull until it bights (2 or 3 pulls), then half choke and one pull starts. From there, click the throttle to idle, let the saw warm up for 3 seconds or so, start giving it some throttle progressively and then get to work. Depends on weather too.... if its cold I'll let the saw warm a little longer.

The M saws are weird. They only have a 3 position switch; off, start and run. I don't really understand the mechanics of how the choke works with 'start', but I figured that you want to get onto run once the saw is started. Maybe I'm wrong. They start easy enough, but if you click them off 'start' and on to 'run', then they die. So much for autotune. If you leave them on start, they die sometimes too. I find you've got to start them on start, take the chain brake off and run them hard at full throttle for 20 seconds or so. Then they idle and run just fine.

Am I doing it wrong?

Shaun

 

[Chris-PA]

I have had no success tuning my strato engined saw no load anyway. The 4-stroking is not that pronounced and it ends up too rich in the cut - I have to tune under load in the cut to get it right. I've read others remark that their stratos don't like to be set rich either.

Some have read my tirades about how these all-position carbs give a fuel/air ratio that increases exponentially with air flow, and leans out with increasing load/decreasing air flow, due to the lack of an air bleed system on the main jet. I have also speculated that the strato air valve may partially act to counteract this effect. IF this were true then:

1. The fuel/air ratio would not get as rich as load decreased, so less obvious misfire/4-stroking

2. If you made it 4-stroke at no load it would not clean up in the cut the same way.

I guess if you are tuning no load with a tach then you still have to run it.