MS310 trouble

[turnkey4099]

One season use on this saw. I kept hoping that it would wear in and turn into a good saw. So far no improvement.

Problem: On cold start it will idle just fine but I have to keep blipping the throttle to get it to pick up rpm until it warms up. If I just hit the throttle it dies. Also having same problem with my 041.

Problem: Bogs in cut. I have to keep easing the bar or it just quits cutting.

This has to be carb problem but I have no clue as to which way to go. I think the bogging is due to too rich on the high.

Was going to try adjusting it yesterday in the field but decided to ask here and have some clue as to which way to go before tinkering with it.

Harry K

 

[jokers]

Harry,

First thing I would check is the Lo screw, sounds lean, from my armchair, LOL. This can also be caused by carb gumming which reduces orifice sizes because of the buildup.

After you have the bottom straightened out, go for the hi speed.

Russ

 

[Joey P]

Stihl has a 2 year warranty on carburation because it is an EPA componant. Bring it to your Stihl dealer and ask for warranty work to be done to it.

 

[lostone]

TK have you tried the role test on it? (start it up let it set for about 30 seconds idling then role it from one side to the other and see if the idle changes)? I'm new to 2 cycle and correct me if I'm wrong, but on a cold engine if the idle was set right, and it was rich on the high screw adj. would this cause it to want to flood out when the throttle was hit full? also causing the bogging that you are talking about at WOT, the reason I'm wondering if it would do this on a engine that is cold until it warms would be the heat from the engine would help it once it warmed to make the excess fuel want to burn rather than flood out. Just a theory I was wondering about, is there any merit to it tech's? Joker I agree with you on the L it does sound like it could be a bit Lean on the L and rich on the H adjustments, but I was wondering if the H was set to rich if it could cause the problem by itself. But this is going off of what little bit I have adjusted carbs (and that is very little) according to Tim's site and Madsens site

 

[wiley_p]

The truth of the matter is never never buy any Stihl saw wxceept for the pro grade saws.

 

[stihltech]

310

You are lean on the bottom side. Either get the low end richened by adjustment, internal adjustment or a new carburetor.
This saw has panned out quite nicely for the consumer. A GOOD starting saw. This one needs to be made right, get it back to the dealer.

Just one statement bothers me, you say the 041 is doing the same thing. I would get a glass jar and check the fuel out.

 

[Chainsaw_Maniac]

Another thing that can happen is that the filter in the fuel pick up can get clogged and needs to be cleaned. (More likly it's something elsew though)

 

[turnkey4099]

Thanks for all the replies. I will attempt adjusting and if that doesn't work - back to the dealer.

I don't think it is fuel as the problems have been there since day one and my other two saws run just fine out of the same can. It sounds just fine - at least to these old ears - out of the cut. The bogging only shows up in the cut. How bad is it? Well I cannot let it self feed with a sharp chain or it will bog right down, I have to baby it.

I am not new to these things, been firewooding for over 30 years now. Never was very confident in screwing around with the carbs tho.

Harry K

 

[lostone]

Originally posted by turnkey4099


Well I cannot let it self feed with a sharp chain or it will bog right down, I have to baby it.

What are your rakers set at?

 

[turnkey4099]

Originally posted by lostone
What are your rakers set at?

Original factory spec. I just sharped the chain with a mild touch-up for the second time. 1st time was also only a mild file job.
Again, the problem has been there since the first day.

Harry K

 

[Hexan]

I have a MS 310 and when my carb was a little too lean on the bottom and way too lean on the top the saw bogged down too but try getting the low end richer to assist when revvin her up and also try richening up the high end to get that torque it's missing. The modern stihl carbs on the 310 allow you to adjust slightly so it might be necessary to take it to the dealer for a more coarse adjustment.

 

[turnkey4099]

It's off to the wood patch this morning. I will play with it a bit to see what happens. If it doesn't turn into a saw, I'll take it to the dealer tommorrow.

Harry K

 

[turnkey4099]

Well, I tweaked it a bit. Richer on the low, leaner on the high. Made quite an improvement. Can't tell yet if the low is fixed now as the saw has to be cold to show it. Last trial cut with the bar buried full lenght (20" bar) in a 30" log it pulled itself through without bogging. I think it could still be leaner but I am a bit fearful of getting too lean. It still isn't cutting anywhere near as fast as the old Johnsered 625 I swapped off for it.

Someday I have to get over my fear of screwing with carbureators. I also thought that was a french word meaning 'don't touch'.

Harry K

 

[glens]

You need to set your low <i>after</i> your high.&nbsp; The low speed jet gets its feed through the high needle in what's called a "dependent" arrangement.&nbsp; In previous carburetor designs they were "independent" and each drew their fuel directly from the reservoir.&nbsp; Now only the high does.

Glen

 

[MacDaddy]

If they both pull off the same supply wouldnt you have to adjust low first then hi because when you hi first then low your low will also change your hi speed so what I would do is to set low and hi a little rich and then lean out the hi slightly and this will lean out your low slightly rule of thumb smoke and no power is rich no smoke and no power lean also lean idle is also eratic and will bog when you hit gas real fast our when cold slightly richen up your low speed and it should go away if you have problems you can email me good luck

 

[glens]

Originally posted by macman101a
... your low will also change your hi speed...

Yes, in a carburetor with independent jets, the low will add overall fuel to the system when the high jet is active.&nbsp; In the EPA carbs the high speed jet is the only thing that controls how much fuel gets into the airstream then.

Attached is a page from "RA_Vergaser_01.PDF".

Glen

 

[MacDaddy]

the carb works off vacum and if the low side has vacum it will pull fuel what you are saying is that at full throtle that is properly set mixture you can run the slow speed screw all the way out and it will not change hi speed also you could run it in all the way and you wouldnt notice a change at hi speed

 

[glens]

I don't know about running the low-speed screw <i>all the way</i> one way or the other; that would be a very abnormal situation.&nbsp; All I'm saying is that in normal use "Full-load fuel flow is determined by the high speed screw" and "Adjusting the low speed screw to change the idle fuel volume does not result in a change to the overall fuel volume".

The MS310 has a carburetor plumbed like the rightmost image in that attached page.&nbsp; Earlier carbs (or direct replacements for them?) are plumbed like in the center image.&nbsp; In those, adjusting the low-speed screw will alter the overall measure of fuel admitted to the airstream at full throttle.&nbsp; The current (newer) design is to eliminate that tendency.

Maybe we're saying the same thing, only differently?

Glen

 

[MacDaddy]

Yes we probably are I also could not down load that image I just want to help him set his saw If I can help please ask via email

 

[Mange]

Originally posted by macman101a
Yes we probably are I also could not down load that image I just want to help him set his saw If I can help please ask via email

I had no problem with it, good so se, then easyer to understand.

Mange