max RPM for various 2-stroke Stihls...

[sperho]

I want to see how my various Stihl power equipment is operating.

I have a BR420 blower that I'd like to make sure is in tune. Lakeside53 mentioned this post how to set the high mixture. Which air nozzle, if any beyond the straight tube that the throttle is strapped to?

Can much be gained in a muffler mod of the BR420? (Not sure I'd want something much louders strapped to my back though, despite the fact I wear earmuffs while operating it).

Also, what's the proper max high speed RPM for a 4-mix FS-110R trimmer? Any other tuning tips there?

Finally, saw related, I'm going to be modding my MS260Pro soon; it was purchased this winter, 10 tanks or so ran through it. I plan to drill two 3/8" holes in the muffler, as per previous recommendations. I plan to set the max RPM to about 13,500 (Is 14k too close to the edge if I want excellent longevity in an otherwise stock saw?). I'd like the extra bump in power that's easily had in this engine, but I don't need to run too close to the 14k limit. Does this rev range this sound reasonable? My saw is equipped with a 20" bar and I'll make sure the fuel is fresh, filter is clean, and saw is warmed up before I make the adjustments.

 

[Lakeside53]

I was getting back to you


Modding the muffler on the 420 will do little - the fan wheel simply stalls above 7600rpm and the tubes can't handle the flow. What's your peak now?, and remember not to leave it at peak... way too lean.

If you have the 420C, the best gain is to simply put on the standard muffler and dump the cat version.

If you have the FAT tube, either the straight or curved END is required as well as the tube body. If you have the narrow tubes, you can get way with no end if you like, but you should have the main tube section beyond the handle assy.

On your 4-mix, the rpm is limited by the igniton so don't go trying to chase it with carb adjustments, and remember, it's a 4-stroke... operating rpm is 7000 (max hp) to 10,500 (ignition cut-off) with the correct length string. Just set you H screw to standard and leave it alone if it's working fine.



13,500 is fine for the 026.

 

[sperho]

I was getting back to you

Thanks Andy - I wasn't sure if you checked your PMs or not and I didn't want to bug you further, so I thought I'd toss it out there...

I'll have to check back in with my current RPM values - I'm still testing my homebrew "tach".

 

[sperho]

Modding the muffler on the 420 will do little - the fan wheel simply stalls above 7600rpm and the tubes can't handle the flow. What's your peak now?, and remember not to leave it at peak... way too lean.

I audio tached my 420C at 7450 RPM WOT with a 4203 708 3408A / 4203 708 6300 curved tube combo tonight. When you say "peak", do you mean the peak RPM when I hunt for it by adjusting the H adjustment screw? (I didn't do that, yet, if so).

If you have the 420C, the best gain is to simply put on the standard muffler and dump the cat version.

Do I actually gain air velocity by doing this or just reduced spool up time? If it's the former and it's a real gain, I would consider doing it, but if it's simply a spool-up gain, then I'll take the clean emissions...

 

[Lakeside53]

I'd just leave it alone if it's pulling 7450.. you might gain a small amount with the non-cat muffler, but not enough to worry.

 

[sperho]

Alone she's left. Thanks.

 

[Pablo26]

While you're at it, how about about max RPM for a '04 O26? My owners manual states 13K for WOT, I have it at 13,200 on the cheapo $24 tach. Thanks in advance.

 

[Lakeside53]

Should be 14k, not 13k... 13k is for the 024.

your setting of 13.2k is o.k. though; nice and conservative.

 

[sperho]

Guess it doesn't matter now how well the thing was running. It was stolen from my shed. Just discovered it tonight. :angry2: :angry2: :chainsawguy: :chainsawguy: :sword:

 

[WRW]

Guess it doesn't matter now how well the thing was running. It was stolen from my shed. Just discovered it tonight. :angry2: :angry2: :chainsawguy: :chainsawguy: :sword:

Key wrap, I hate to hear that.

 

[sperho]

Enough of the mess on my property already, I went out and supported Stihl Incorporated again today by purchasing a new BR600. Can someone say, "Stihl kicks!"?

 

[Lakeside53]

The 600 ROCKs!! Run it on Stihl Ultra at 50:1 and it will be very happy.

Been a good day for Stihl.. I got a KM130, 0->135 HT attachment, pole pruner, string head etc etc etc . Now I need to sell my echos, again.... Sigh...

 

[sperho]

Man this 600 kicks. Almost as much as Huskies... I don't know if my spine can handle the torsion that this thing applies, but we'll see - especially this fall. Starts like a dream, too. 2 bulb presses, choke on, one pull, running, switch off choke, warm for 15 seconds, start creating wind. Two thumbs up.

 

[RED-85-Z51]

The 600 ROCKs!! Run it on Stihl Ultra at 50:1 and it will be very happy.

Been a good day for Stihl.. I got a KM130, 0->135 HT attachment, pole pruner, string head etc etc etc . Now I need to sell my echos, again.... Sigh...

What Echo's do you have to sell?