400c Rumors… or just internet trolls.

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How's cooling effected at higher altitude? Lots of air-cooled electronics are de-rated at higher altitude, even though electrics don't care, they have reduced cooling capacity due to the thinner air.

Saw cooling due to altitude probably reduces in line with power reduction due to altitude, so likely not a consideration at all.
Not certain at all. I have no experience with running saws at elevation
 
Wonder if really that close.

This guy I believe worked as a stihl tech.

620 60cc is 7cc smaller. List 629. Weighs close to 1lb more PHO dry.
400 67cc List 1029
He said both stock with muffler mod and running 3/8 7T.


My only thought on that is that he should have ran 2 new chains instead of putting a used chain on the 400. I've been cutting hard dry ash as big as what he was using and I can tell after several cuts how the chain is cutting. 20231215_124456.jpg
 
How's cooling effected at higher altitude? Lots of air-cooled electronics are de-rated at higher altitude, even though electrics don't care, they have reduced cooling capacity due to the thinner air.

Saw cooling due to altitude probably reduces in line with power reduction due to altitude, so likely not a consideration at all.
Less power equals less heat and most of the cooling comes from the phase change of the fuel.
 
Owner manuals state that recommend a minimum 89 octane. Also recommends MotoMix and that has 93 octane. Attached is snips from the owners manuals.
.

View attachment 1138392View attachment 1138393
I have always ran ethanol free premium in my two stroke equipment. Not because it needs it, but rather it's a little bit of insurance.
Compression ratio wise saws do not need premium or mid grade fuel. Compression ratio dictates octane requirement and the Compression ratios of chainsaws is very low.
I also find it strange that Stihl saws not to run marine type oils, but yet reccomendes Stihl Ultra, which is formulated like a marine oil.
 
He must have a Supreme running 600sx, cause I'll tell you first hand, my 400 out runs my neighbors 620p.
Yes. I think what he has is a supremely tuned 620. Tuned better than the automatic tune in the 400 by quite a bit, imo.

If I could get my 590 to run near that, It wouldn't be first on the list of the cliff throw candidates. Even though it definitely has other shortcomings.
 
How's cooling effected at higher altitude? Lots of air-cooled electronics are de-rated at higher altitude, even though electrics don't care, they have reduced cooling capacity due to the thinner air.

Saw cooling due to altitude probably reduces in line with power reduction due to altitude, so likely not a consideration at all.
Cooling isn't effected as much as loss of oxygen to the burn cycle. Hence the need to lean it out. Sea level to 2000ft changes very little. Day temps verses evening probably effects it more.
 
My only thought on that is that he should have ran 2 new chains instead of putting a used chain on the 400. I've been cutting hard dry ash as big as what he was using and I can tell after several cuts how the chain is cutting. View attachment 1138386
Fresh off the reel is kind of an equalizer.
 
I agree with loads of the comments on this post. Too many people using saws that they should not be using. I have seen some horrors over my life with people and saws, and always those people claiming the saws are rubbish or useless are part time saw users. I don't know the saw in question, but if grenaded, I would say user problem caused it through ignorance.

I run all 2-strokes at 20-25/1 all my life and never grenaged a saw or power tool in my lifetime. Now retired. I know makers claim 50:1, but never have I ever followed this recommendation in all my years as a wood cutter, and none of the other cutters I worked with over many decades did this lean mix ever.
But we also ran them rich on purpose up here in the North with peat hills and mountains to hold back the midgie's a bit. So only a few hundred would bite you instead of clumps of 1,000's
 
My only thought on that is that he should have ran 2 new chains instead of putting a used chain on the 400. I've been cutting hard dry ash as big as what he was using and I can tell after several cuts how the chain is cutting. View attachment 1138386
We also saw vids like this when the Echo 7310 came out and it was beating 372s and 572s lol. Had to be some camera or chain magic going on there. They’re not a bad saw, but they certainly aren’t a fast saw either
 
I just sold a ms391 and going to buy a ms400 with 25” bar. I can upgrade to a light bar at time of purchase for a few bucks more. Is the Stihl bar the one to go with or maybe one of the aftermarket ones if they can. I’m just cutting firewood for myself so not getting a big amount of use. I’m after weight saving the most. The 391 was a tank so hope to be able to have a noticeable difference.
 
Yes. I think what he has is a supremely tuned 620. Tuned better than the automatic tune in the 400 by quite a bit, imo.

If I could get my 590 to run near that, It wouldn't be first on the list of the cliff throw candidates. Even though it definitely has other shortcomings.
I highly doubt he can tune as well as m-tronic or any other electronic fuel management system.
 
I just sold a ms391 and going to buy a ms400 with 25” bar. I can upgrade to a light bar at time of purchase for a few bucks more. Is the Stihl bar the one to go with or maybe one of the aftermarket ones if they can. I’m just cutting firewood for myself so not getting a big amount of use. I’m after weight saving the most. The 391 was a tank so hope to be able to have a noticeable difference.
If you don’t mind paying for it, the Stihl light is absolutely a nice lightweight bar
 
I just sold a ms391 and going to buy a ms400 with 25” bar. I can upgrade to a light bar at time of purchase for a few bucks more. Is the Stihl bar the one to go with or maybe one of the aftermarket ones if they can. I’m just cutting firewood for myself so not getting a big amount of use. I’m after weight saving the most. The 391 was a tank so hope to be able to have a noticeable difference.
I've read the 400's oiler is pretty well maxed out with a 20". I don't own one, but it sure wouldn't hurt to ask around before spending $$$$$$$$.
 
I just sold a ms391 and going to buy a ms400 with 25” bar. I can upgrade to a light bar at time of purchase for a few bucks more. Is the Stihl bar the one to go with or maybe one of the aftermarket ones if they can. I’m just cutting firewood for myself so not getting a big amount of use. I’m after weight saving the most. The 391 was a tank so hope to be able to have a noticeable difference.
When I researched light bars after buying my 500i, Stihl light bars were the go-to - if you could get them. Lightest and plenty durable, at reasonable price. Some of the aftermarket bars were more expensive - if you could get them.

If you can't get the Stihl light bar, just run whatever you can get. Been running Tsumura with no complaints.
 
When I researched light bars after buying my 500i, Stihl light bars were the go-to - if you could get them. Lightest and plenty durable, at reasonable price. Some of the aftermarket bars were more expensive - if you could get them.

If you can't get the Stihl light bar, just run whatever you can get. Been running Tsumura with no complaints.
When I talked to the dealer it didn’t sound like it would be a problem getting one. It was $50 more with the light bar which I’m sure was a Stihl.
 
I've read the 400's oiler is pretty well maxed out with a 20". I don't own one, but it sure wouldn't hurt to ask around before spending $$$$$$$$.

Even for someone who isn't all that mechanically inclined upgrading the oiler is pretty simple, whether you get the pump guts or the whole 461R pump itself (even easier) it's not hard at all, and totally worth it even if you only run a 20"..I've never heard anyone complain they had the option to put more oil on the bar. I tried my 400 Kev ported just for a few cuts with 32" and it oiled it well with the upgrade, actually didn't do too bad pulling it either considering it's only 67cc.
 
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