Stihl MS260 Over-Fueling??

[spudulike]

Good points - I do my taching 1/2 mile down the road in the middle of nowhere - get some strange looks but who cares - run the saw up to hot and then tach to around 13,000rpm - the manufactures max is 14,000 but unless you really care about that little extra chain speed or have spent time tuning the thing then the safety margin is worth having.

 

Next thing is to open up that muffler, bring the squish down and open up those ports and tune to 14,000.................

[hawthornheavyhorses]

Pulled the cap off today, and tuned, just needed a tiny tweek on the H to bring the revs down, sounds much more "normal", guess that must be the four stroking sound, think I am am getting an ear for it now.

 

Tached it to around 13200 which seemed to be a sweet spot, but might just bring that down a little.

 

Put it to work on a big log for a bit before I came home, will check plug colour when i go back to work tomorrow.

 

Luckily I have a yard where I can tune my saw where the noise is not going to upset anyone!

 

Fingers crossed all problems are solved, but just two more questions.

 

1. The H screw seems to move quite easily now the cap is off, much easier than the L. I damaged the little red centre part a little, but once I am happy should I get a new one and put back in to stop it working loose?

 

2. Adjusting the H lowered the L speed down to about 2650-2700 rpm. Should I bother bringing this up to 2800? If so should I lean the L, or bring it up on the LA? Seems to idle very nicely anyway.

 

Many thanks for all your help as always.

[GardenKit]

Glad its working. You should really just go through the L setting procedure again, as the idle mixture will have been altered by altering the H mixture.

In theory you should replace the limiter with new. I must admit I tend to leave them off and have not had them move as far as I am aware, but it may be as well to be safe rather than sorry.

[spudulike]

Pretty much the same as Barrie, I have a set procedure on setting up the L screw and that is winding it in until the saw races and then backing it out until you hear the saw have a slight pop in its exhaust note and falls back to a reasonable idle, I then adjust the LA and see how it revs from idle to flat out and how the saw responds to blipping the throttle.

 

You can find smaller saws are very fussy on the L screw where larger ones are not, small saws can bog a bit if the L screw is a bit lean so trying it on a bit of good timber can help.

 

When cold, some saws take around 30 secs to stop bogging from idle and then work fine when warm - the 345, 346, 350 Husky range are usuall candidates for this but the Stihl 026/260 are generally OK.

 

As Barrie says - it is worth checking the high and low speeds if the L screw is adjusted, on some carbs, adjusting the L screw can effect the H setting - I have had this on a MS260.

[hawthornheavyhorses]

Thanks guys, will try resetting the L tomorrow then. It's running really nicely and seemed to be cutting really well, so think it's nearly there. Will be interesting to see what the plug looks like tomorrow.

 

Barrie, are you able to supply the limit cap? It's part number 6 on here:

 

Select a Carburetor or Component [Frontstep Customer Center 5 Frontstep, Inc.]

 

Helpfully there is no part number though!

 

As you can see from the drawing there is no spring to hold the needle in place so that would expain why it moves more easily.

 

It's a tiny little red plastic cap, that fits into the alloy collar.

[hawthornheavyhorses]

Hi Guys,

 

You were absolutely right spud, reset the L again the then the H was running a bit rich, so then adjusted that too.

 

Spent half hour cross cutting some timber this evening and it is cutting really well, mix of small and large logs, no bogging or signs of the original problems. Started up perfectly from hot and cold. It sounded and even smelled right.

 

I'll spend a day cutting with it to make sure, but think this one is solved.

 

I will put a limiter cap back in once I'm 100% sure all is ok.

 

Thanks for all your help, it's been very interesting sorting it out, and much quicker than the 8 week wait at the dealers!