Stihl MS 260 - Correct RPM for carburetor setting?

[phoenixmanz]

So I ordered a tachometer to check what RPMs the MS260(gifted to me recently) was running, since it wouldn't idle well and kept going off.
It's trying to idle around 1000 RPM and max speed is about 11k.
I read somewhere that idle should be about 3k and max 14k.
Could someone confirm that? Or point me to official specs for the settings? I couldn't find a manual that specifies the idle and max RPM

 

[ammoaddict]

From the Stihl MS260 Service Manual:

Adjust idle speed with a tachometer. Adjust specified engine speeds within tolerance of ± 200 rpm.

1. Adjust engine speed with idle speed screw (LA) to 3,600 rpm.

2. Turn the low speed screw (L) clockwise or counterclockwise to obtain the maximum engine speed.
If this speed is higher than 3,700 rpm, abort the procedure and start again with step 1.

3. Use the idle speed screw (LA) to set engine speed again to 3,300 rpm.

4. Set the engine speed to 2,800 rpm with the low speed screw (L).

5. Set maximum engine speed with the high speed screw (H) (see Specifications) (14,000 rpm for ms260)

 

[bwalker]

In my expiereance they run better when spun up to around 14800. This is with a trimmed choke, timing advanced a bit, a muffler mod and a WT-194 though. All of these mods I consider as must haves for a MS260Pro

 

[ballisticdoughnut]

On a stock 260 14,000 RPM is fine on a fully hot saw after making several cuts.

 

[phoenixmanz]

From the Stihl MS260 Service Manual:

Adjust idle speed with a tachometer. Adjust specified engine speeds within tolerance of ± 200 rpm.

1. Adjust engine speed with idle speed screw (LA) to 3,600 rpm.

2. Turn the low speed screw (L) clockwise or counterclockwise to obtain the maximum engine speed.
If this speed is higher than 3,700 rpm, abort the procedure and start again with step 1.

3. Use the idle speed screw (LA) to set engine speed again to 3,300 rpm.

4. Set the engine speed to 2,800 rpm with the low speed screw (L).

5. Set maximum engine speed with the high speed screw (H) (see Specifications) (14,000 rpm for ms260)

Great thanks! Any chance you have a digital copy of the service manual you can share?

 

[phoenixmanz]

In my expiereance they run better when spun up to around 14800. This is with a trimmed choke, timing advanced a bit, a muffler mod and a WT-194 though. All of these mods I consider as must haves for a MS260Pro

Thanks for the suggestion! Don't think I feel comfortable yet with modding the 260. But I do intend to rebuild an old Wood Boss 024 AV at some point, to learn more about the internals of a chain saw. Any recommendations for that one?

 

[ammoaddict]

Great thanks! Any chance you have a digital copy of the service manual you can share?

I don't. You can ask for one on the beg for manuals thread. Some one will hook you up.

 

[bwalker]

On a stock 260 14,000 RPM is fine on a fully hot saw after making several cuts.

A tach reading is only accurate on an engine that's at full operating temp. Like wise tuning by ear should be done with a warm engine as well.

 

[bwalker]

Thanks for the suggestion! Don't think I feel comfortable yet with modding the 260. But I do intend to rebuild an old Wood Boss 024 AV at some point, to learn more about the internals of a chain saw. Any recommendations for that one?

No expiereance with that one.
The mods I mentioned are very easy to do.
The muffler mod is a must do an 260.

 

[phoenixmanz]

No expiereance with that one.
The mods I mentioned are very easy to do.
The muffler mod is a must do an 260.

Ohh you got me itching to try it out now do the RPMs mentioned above still apply after the muffler mod? Or should it be tuned differently with the 3x3/8" holes mod?

 

[phoenixmanz]

I don't. You can ask for one on the beg for manuals thread. Some one will hook you up.

Did that, thanks a lot for the tip!

 

[bwalker]

Ohh you got me itching to try it out now do the RPMs mentioned above still apply after the muffler mod? Or should it be tuned differently with the 3x3/8" holes mod?

Yes, it will be fine at the factory spec of 14k after a muffler mod. Each saw is different and it takes some playing to figure out what it likes best.

 

[phoenixmanz]

In my expiereance they run better when spun up to around 14800. This is with a trimmed choke, timing advanced a bit, a muffler mod and a WT-194 though. All of these mods I consider as must haves for a MS260Pro

So I looked around for a wt-194 and the original seems to be somewhere around $100. There are however also what I assume to be knockoffs available, ranging from $20 to $50 in price(e.g. Cheap Carb kit ). Are the cheaper ones any good?

Also found an original Tillotson HU-136A that's supposed to be the same as a wt-194 for about $55.

What do you guys think it's a good option? I don't want to spend much on mods right now

P.S. I have the non pro version of the MS 260.

 

[stihltech]

DO NOT BUY AN AFTERMARKET CARBURETOR (for the 100th time)!
Or at least buy a few so 1 might work.
When you work on these daily, the ear is just as accurate, and tends to end up with a motor that is not too lean. In the wood is where it counts

 

[SteveSr]

What do you guys think it's a good option? I don't want to spend much on mods right now

Why are you replacing the carb? What is wrong with the one that is on it now?

P.S. I have the non pro version of the MS 260.

Stihl used multiple carbs on this and most saws. What is the manufacturer and model that is currently on this saw? Also note that the later non-pro saws came with a compensating carb, the same as the Pro.

 

[phoenixmanz]

Why are you replacing the carb? What is wrong with the one that is on it now?


Stihl used multiple carbs on this and most saws. What is the manufacturer and model that is currently on this saw? Also note that the later non-pro saws came with a compensating carb.

Because I assumed the stock carbs were inferior I'll check what carb is on there now, plan to open up and do a deep clean on the saw this weekend.

 

[stihltech]

Stock carbs inferior? I guess you assumed that from the "there is a better carb" posts on here. It depends on what you have. Many a low speed only carb has been woke up by and extra 3/8 hole in the exhaust outlet.
Do you just want you saw to run correctly or do you want to modify for extra power? That is the question.
Bigger cam and nitrous will get you the latter

 

[ZeroJunk]

I'd like to have a MS260 that would idle at 1000 RPM.

 

[phoenixmanz]

Stock carbs inferior? I guess you assumed that from the "there is a better carb" posts on here. It depends on what you have. Many a low speed only carb has been woke up by and extra 3/8 hole in the exhaust outlet.
Do you just want you saw to run correctly or do you want to modify for extra power? That is the question.
Bigger cam and nitrous will get you the latter

So I finally got around to working on the ms260. Drilled some holes in the muff, removed the limiter cap on the H screw and calibrated the carburetor, which in fact, is a walbro. She runs beautifully now Threw on a new 45cm/18" bar and chain on it and it cuts like butter

Thank you all for your input!

 

[bwalker]

Stock carbs inferior? I guess you assumed that from the "there is a better carb" posts on here. It depends on what you have. Many a low speed only carb has been woke up by and extra 3/8 hole in the exhaust outlet.
Do you just want you saw to run correctly or do you want to modify for extra power? That is the question.
Bigger cam and nitrous will get you the latter

The stock carbs on the 260 variant are often fixed HS circuit carbs and run like crap. A WT194, muffler mod and a cut flywheel key makes them run as they should. Which still isn't as good as a 346xp, but is a big improvement.