# Chainsaw Bogging with throttle pressure



## iod0816

Its the chainsaw on my tag. It bogs down it seems and stalls out when I open the throttle. Weather is 30-50 when I'm cutting and I'm trying to run 40:1, 93 only. Trying that is by using Stihl Ultra bottles and pouring a little less but I always have some left over gas in the can... So anyhow, I've ran about 25 hours and took it for a tune up. Since the tune, I've ran about 2-3 and noticed with this particular can it's been bogging and stalling. Gas is fresh. He set it for 40:1... The 2-3 hours of running has been in warmer weather. Are the settings off or...? Is it the weather? Air Filter is clean... Saw has been mine and only mine since new.

Also when she's warmed up, not so much of an issue...

Thanks!

Ian


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## wkpoor

If its  a tune fix then its the Low speed screw. Back out 1/8 turn at a time and try. It may affect idle so that may need changed too.


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## CTYank

Since you "took it for a tune up" take it back, and ask for a follow-up.

Mess around with it, and don't expect much help.

Eventually, you want to learn how to make simple, basic carb adjustments. If only to cope with temp changes. Then you have a chance of learning to detect when things aren't right- carb internals, seals, whatever.


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## bioman

turn the low screw 1/4 ccw and mix 50:1 be safe with the big saw!


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## golfandwoodnut

try some seafoam, fixed my problem that was similar.


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## Danno77

You don't have a winter setting like on some of the stihls, do you?


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## wkpoor

If you don't have experience tuning a chainsaw its best to learn from someone that knows how. Its done by sound and its impossible with words to explain what 4 cycling sounds like. The top end tune is very important. Too leen could lead to premature top end failures and too rich your loosing power. I'm very good at tuning and still when I raced I had someone even more experienced tune my saw to get a few hundredths a sec more from it. It takes a keen ear and sometimes a tach to get it just right. If your saw has a limiter on it you might only be able to adjust in the cut (with the help of an assistant) or with times tests. Many times at GTGs we would tune each others saws while in a cut.


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## smokinj

iodonnell said:
			
		

> Its the chainsaw on my tag. It bogs down it seems and stalls out when I open the throttle. Weather is 30-50 when I'm cutting and I'm trying to run 40:1, 93 only. Trying that is by using Stihl Ultra bottles and pouring a little less but I always have some left over gas in the can... So anyhow, I've ran about 25 hours and took it for a tune up. Since the tune, I've ran about 2-3 and noticed with this particular can it's been bogging and stalling. Gas is fresh. He set it for 40:1... The 2-3 hours of running has been in warmer weather. Are the settings off or...? Is it the weather? Air Filter is clean... Saw has been mine and only mine since new.
> 
> Also when she's warmed up, not so much of an issue...
> 
> Thanks!
> 
> Ian



If its not an issue after it warms up and is easy enough to start, I would just let it warm up first. Guess the big thing hear is if that saw is running good warm there not much of a reason to tune cold.


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## Danno77

Good point, Jay. I guess I read the the post but ignored that last part.


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## smokinj

Danno77 said:
			
		

> Good point, Jay. I guess I read the the post but ignored that last part.



Its nice to keep them in a heated space. My 460 I have put it in the cab of my s-10 (very tight fit) to warm it up first. These are days I always say never again.


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## wkpoor

My saws all sit out in the unheated building and I never have any issues with basic tune. When it gets real cold like 10 degrees I do richen up the high side but rarely need to adjust the low. For me its mostly about high side tune. And for plain ole firewood cutting it mostly just a summer winter thing. Not a daily temperamental deal. Only time a I get crazy about tune is timed cuts at a GTG.


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## smokinj

wkpoor said:
			
		

> My saws all sit out in the unheated building and I never have any issues with basic tune. When it gets real cold like 10 degrees I do richen up the high side but rarely need to adjust the low. For me its mostly about high side tune. And for plain ole firewood cutting it mostly just a summer winter thing. Not a daily temperamental deal. Only time a I get crazy about tune is timed cuts at a GTG.



I wish someone would do a Measured gas test at on of these things. Each saw gets only 20 oz's and see who cuts the most.


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## wkpoor

smokinjay said:
			
		

> wkpoor said:
> 
> 
> 
> 
> My saws all sit out in the unheated building and I never have any issues with basic tune. When it gets real cold like 10 degrees I do richen up the high side but rarely need to adjust the low. For me its mostly about high side tune. And for plain ole firewood cutting it mostly just a summer winter thing. Not a daily temperamental deal. Only time a I get crazy about tune is timed cuts at a GTG.
> 
> 
> 
> 
> I wish someone would do a Measured gas test at on of these things. Each saw gets only 20 oz's and see who cuts the most.
Click to expand...

Thats a good one. Everyone I've held or been to is all about speed. Fuel to get there has never been brought up. We did do fuel tests though in timed cuts with a Stihl 660. If I remember we used 4 different fuels. Results were inconclusive. But basically it proved the AvGas didn't ad power to that saw.


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## smokinj

wkpoor said:
			
		

> smokinjay said:
> 
> 
> 
> 
> 
> 
> 
> wkpoor said:
> 
> 
> 
> 
> My saws all sit out in the unheated building and I never have any issues with basic tune. When it gets real cold like 10 degrees I do richen up the high side but rarely need to adjust the low. For me its mostly about high side tune. And for plain ole firewood cutting it mostly just a summer winter thing. Not a daily temperamental deal. Only time a I get crazy about tune is timed cuts at a GTG.
> 
> 
> 
> 
> I wish someone would do a Measured gas test at on of these things. Each saw gets only 20 oz's and see who cuts the most.
> 
> Click to expand...
> 
> Thats a good one. Everyone I've held or been to is all about speed. Fuel to get there has never been brought up. We did do fuel tests though in timed cuts with a Stihl 660. If I remember we used 4 different fuels. Results were inconclusive. But basically it proved the AvGas didn't ad power to that saw.
Click to expand...


I thought the same thing back in 2006 when 5 gallons of mix 93 was around 15 bucks. Now with the same 5 gallons is around 25 bucks. Then you take a 441 for the day putting more rounds on the ground and less fuel, well it starts to look a little silly thinking one cookie at .0001 seconds faster than the other guy means anything. (These would really be a better test on the daily production saw) And who is really the fastest.


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## WoodMann

As has been stated B4- play with the carb settings. Carb adjustment tool, best 4 bucks I ever spent.............


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## iod0816

It does have a cold air intake setting but nothing other than that. I played with a different batch of 93 and made sure it was 40:1. Let it warm in the cab before cutting on the ride there, started 1st pull after first on pull choke. 25 degrees out this AM. No bogging and just cut a cord of black locust... Can it really be that sensitive to the amount of oil? Will have to learn how to carb adjust myself definitely tho!

Just thought it was weird... Never had it happen before tho its was the first time I went to this dolmar dealer...


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## smokinj

iodonnell said:
			
		

> It does have a cold air intake setting but nothing other than that. I played with a different batch of 93 and made sure it was 40:1. Let it warm in the cab before cutting on the ride there, started 1st pull after first on pull choke. 25 degrees out this AM. No bogging and just cut a cord of black locust... Can it really be that sensitive to the amount of oil? Will have to learn how to carb adjust myself definitely tho!
> 
> Just thought it was weird... Never had it happen before tho its was the first time I went to this dolmar dealer...



No. Did you clean the air filter or anything else different?


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## Danno77

I'd look at the gas before the oil. Did you say you got NEW 93 and remixed? I know in your first post you were saying your gas was fresh. Any difference in the sources of the gas from the first time and gas you used today?

I would suggest that everything is ok at this point, but keep us posted.


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## iod0816

So after experimentation with the places I buy my gas from, Shell is by far the best (by me). Clean air filter, same temps and settings, I found that the higher quality stations like shell or Mobil have better quality gas than some other "marts"... If you burn it same day, little difference. If you burn it over 30 days, big... Bogging was from 15 to 30 day old gas from cheapo mart... And there really isn't a price difference! Prolly sneaking some more ethanol or other fillers in... 

So Mobil or shell for me only now!


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## Danno77

Glad you got it pinned down. Maybe I'm just lucky, but the gas I get around here all seems to be pretty good. I guess I don't shop at ALL of the gas stations, though, so maybe luck doesn't have much to do with it. ;-)


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## MasterMech

iodonnell said:
			
		

> It does have a cold air intake setting but nothing other than that. I played with a different batch of 93 and made sure it was 40:1. Let it warm in the cab before cutting on the ride there, started 1st pull after first on pull choke. 25 degrees out this AM. No bogging and just cut a cord of black locust... Can it really be that sensitive to the amount of oil? Will have to learn how to carb adjust myself definitely tho!
> 
> Just thought it was weird... Never had it happen before tho its was the first time I went to this dolmar dealer...



I know I'm late to the party.... Definetly sounds like the saw is just a tad on the lean side overall. Even with the "cheapo" gas, the oil you're using has stabilizers in it and should be able to keep the fuel decent for 30 days or more.

+1 on learning what a well tuned saw sounds like.  Too many adjust a saw like a 4-stroke mower and wind up setting them too lean.

To me it pays to be precise with the mix ratio.  Too lean gets real expensive and over rich is just annoying with the extra smoke and carbon buildup.  I have seen noticeable differences with different oil/fuel ratios in various pieces of equipment but you have to be way off, not just a couple points either way.  Quality of the oil makes a difference as well as you need less of the good stuff.  

Maybe I'm a bit anal but I am rediculously uptight about my mixing process.  You mention that you try to achieve 40:1 by "pouring less" in.  40:1 is 3.2oz of oil in 1 gallon of fuel. You'll need 3.25 quarts of fuel to make 40:1 with the 2.6oz container of Stihl's HP Ultra oil.  I used to mix 50:1 with the same oil (I'm currently experimenting with another oil/ratio.) and the procedure would be the same for you @ 40:1 just using less fuel.

1.) I almost always mix @ the pump. I know this isn't convenient for every one and if you frequently have to mix @ home then you can Sharpie a line on your mix can @ 1 gal, 3.25 qts (.8125 of 1 gallon), whatever you need to get your target ratio but the pump is more precise.

2.) I'll add roughly half the required amount of fuel to the can, it doesn't have to be empty if you are mixing at the pump.  You can still dispense the right amount  somewhat accurately.

3.) Open the bottle of oil and add it to the fuel.  Then using the pump, fill the "empty" bottle with a little fuel and shake it gently to wash the oil from the bottle.  Dump that into the can and repeat if desired.

4.) Add the remaining amount of fuel to the can and your done.  Shake the can gently after you put the spout back on and you're ready to run.


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## Thistle

MasterMech said:
			
		

> 2.) I'll add roughly half the required amount of fuel to the can, it doesn't have to be empty if you are mixing at the pump.  You can still dispense the right amount  somewhat accurately.
> 
> 3.) Open the bottle of oil and add it to the fuel.  Then using the pump, fill the "empty" bottle with a little fuel and shake it gently to wash the oil from the bottle.  Dump that into the can and repeat if desired.
> 
> 4.) Add the remaining amount of fuel to the can and your done.  Shake the can gently after you put the spout back on and you're ready to run.



+1  I've done same exact thing for over 25 years....


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## mecreature

I like mixing at the pump too. When I am filling for a fishing trip for the 9.9 merc I mix 3 gallons and fill other containers with that. 

small engines are funny about their gas. especially 2 strokes.

I need to get a better grasp on the tuning thing also.


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## smokinj

mecreature said:
			
		

> I like mixing at the pump too. When I am filling for a fishing trip for the 9.9 merc I mix 3 gallons and fill other containers with that.
> 
> small engines are funny about their gas. especially 2 strokes.
> 
> I need to get a better grasp on the tuning thing also.



You sould be able to hear it a mile away when one is not in tune. Purssure you apply while cutting you can keep one running almost perfect though out a cut.
This really comes in handy on those very long cuts. """"Listen to the Sound Wave""""""
http://web.archive.org/web/20051018212959/www.madsens1.com/sawtune.htm


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## Singed Eyebrows

iodonnell said:
			
		

> Its the chainsaw on my tag. It bogs down it seems and stalls out when I open the throttle. Weather is 30-50 when I'm cutting and I'm trying to run 40:1, 93 only. Trying that is by using Stihl Ultra bottles and pouring a little less but I always have some left over gas in the can... So anyhow, I've ran about 25 hours and took it for a tune up. Since the tune, I've ran about 2-3 and noticed with this particular can it's been bogging and stalling. Gas is fresh. He set it for 40:1... The 2-3 hours of running has been in warmer weather. Are the settings off or...? Is it the weather? Air Filter is clean... Saw has been mine and only mine since new.
> 
> Also when she's warmed up, not so much of an issue...
> 
> Thanks!
> 
> Ian


 If it acts up again run it at high speed & see if it comes right back to idle. If not you could have crank seals that are going. Right Blades? Hopefully your 7900 is ok now, Randy


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## bpirger

Jay, that is an outstanding link you posted.....thanks!


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