MS 260 poor idle and stalling

[albert]

There were a few posts over the winter with this issue. Since then I have used mine a bit and now it idles ok. I am thinking it may have been carb icing or fuel puddling due to cold crankcase and boot. It was below freezing most times the problem occured. I didn't have any problems with the other saws includding a 026 ( which I swapped carbs with to no avail ) same fuel ect. The 026 ran fine with the 260's carb but 260 still ran the same with the 026 carb. I didn't try to use the winter shutter because I never had to with the the othe saws. I am more convinced the ms 260 cylinder, 44.7mm, porting or case has some bearing on this issue. What do you think?

 

[blsnelling]

I just tuned another one last week doing the exact same thing. It could not be tuned out of it.

 

[albert]

was it stock?

 

[blsnelling]

Yes. 44mm 026 too.

 

[albert]

How does it act fom a cold start? Fixed a couple that ran ok and adjusted normally then when pulled out of a hard cut wouln't idle, No vac. leaks, found nozzle checkvalves leaking @ idle. new checkvalves fixed them

 

[blsnelling]

Seems to be a problem when hot. I had 3 or 4 different carbs on my modded 260 and they all did it. It was only cured when I went to the 044 carb. So what's this check valve you're talking about.

 

[albert]

The main nozzle, has a checkvalve in it. Should only flow fuel on open throttle. It's usually #22 on the walbro wt parts breakdown. It's the brass main nozzle in the venturi. Low presure from a open throttle opens it. Hi presure in the venturi (closed throttle shuts it)

 

[Lakeside53]

Never had one that couldn't be made to run right... it's not an option when a customer brings in a saw - you can't hand it back broken.

What albert is refering to is called an "outlet valve". Cheap... and always suspect in the case of poor idle or puddling.

 

[albert]

Any of the other guys that had the same issue, did you get it solved?

 

[Lakeside53]

I'm thinking you had carb icing...

 

[Boca_5404]

Never had a problem getting mine set rite. I will say its very temperamental, If the weather changes much ya better have a screw driver handy.

My guess is quite possibly something else is wrong, I would look at filter, fuel line pulse line. I'm sure Stihl hasn't been making 026 for years so they can't be tuned.

 

[blsnelling]

Good info here. Is this outlet valve available seperately from Walbro?

 

[STEVEGODSEYJR]

026 stuttering?

My 026 seems like it does the same thing. It runs good in the cut and when you pull it out and try to cut something else it kinda stutters . You have to blip the throttle a few times to get it goin again. I tried adjusting the carb low side and dosen't seem to make a difference. Maybe we are on to something.

 

[blsnelling]

My 026 seems like it does the same thing. It runs good in the cut and when you pull it out and try to cut something else it kinda stutters . You have to blip the throttle a few times to get it goin again. I tried adjusting the carb low side and dosen't seem to make a difference. Maybe we are on to something.

That's exactly what they do. A couple blips of the throttle and the excellent throttle response is back. Let it set for a few seconds and it loads up again. Does it in the summer time too.

 

[Lakeside53]

Good info here. Is this outlet valve available seperately from Walbro?

yes, and Stihl.

For guys rebuilding the MS260 WTE series carbs, the metering arm is NOT level with the top or chamber bottom. IIRC, it's 25 thou down from the top.

 

[2000ssm6]

This looks like a good sticky thread.

 

[albert]

The outlet/nozzle checkvlave is item 22 on walbro's parts list, for a wt 194 and a wt 22C .The saw I have does it with known good wt 194, 22C, 426, and wte carbs. It is not the first on that I've run into. My 026 does not have the problem. when the weather is warmer it is less of a problem but it still takes tinkering with the L mix. I've let it idle then tip the bar down and speed doesn't change. Other times after it idles for 30 seconds it doesn't have good response. If you make it the slightest bit richer it stalls when you pick it up after sittting on the ground idling for more than 30 seconds

 

[theoldfox]

026 idles problem

Sorry for late reply but Ive been having exactly this problem also and this post describes my saw exactly!
Runs like a dream at WOT in cut and wont idle directly afterwards. Nurse the throttle a bit and it can come right. Some days leaning the "L" screws works and I think have the issue solved . It happens again next time and making it richers seems to work. Ive tried every combination!!!

Ive almost learnt to put up with it!! But havent given up yet!!

Only mod on the saw is muffler.

Good Thread!!!

 

[Kenskip1]

Idle Problem

From the sounds of this thread, it appears that gas is puddling up inside the crankcase at idle At WOT this clears the mix out and the saw runs the way it should. My 028 does this on occasion, even with 165 lbs of compression.Is your mix fresh? Like you I have gone through the carb but could not find anything wrong, Ken

 

[blsnelling]

Sorry for late reply but Ive been having exactly this problem also and this post describes my saw exactly!
Runs like a dream at WOT in cut and wont idle directly afterwards. Nurse the throttle a bit and it can come right. Some days leaning the "L" screws works and I think have the issue solved . It happens again next time and making it richers seems to work. Ive tried every combination!!!

Ive almost learnt to put up with it!! But havent given up yet!!

Only mod on the saw is muffler.

Good Thread!!!

Unfortunately, this is just a characteristic of many 026/260s. I tried several different carbs on my 260 and never got rid of the problem. I've seen the same thing with stock 260s. Mine only quit this when I went to the 038 intake elbow and 044 carb. This is not a mod for a stock saw though.