400.1 first impression

[jurchybald]

I ported one, have two more to do. I did cut the base and than use JB weld to reconstruct that extension back. Went couple of times in and out. Didn't find any real gains to be honest. it seems it does like higher exhaust.
Second one I will try only BGD and squish cut to see if it's worth all the extra work.

 

[Duane(Pa)]

I ported one, have two more to do. I did cut the base and than use JB weld to reconstruct that extension back. Went couple of times in and out. Didn't find any real gains to be honest. it seems it does like higher exhaust.
Second one I will try only BGD and squish cut to see if it's worth all the extra work.

What does the band look like from the factory? It would probably be one of the cheapest things they could do to "copy" stuff they see here...

 

[jurchybald]

What does the band look like from the factory? It would probably be one of the cheapest things they could do to "copy" stuff they see here...

 

[Sloughfoot]

I ported one, have two more to do. I did cut the base and than use JB weld to reconstruct that extension back. Went couple of times in and out. Didn't find any real gains to be honest. it seems it does like higher exhaust.
Second one I will try only BGD and squish cut to see if it's worth all the extra work.

What stock timing numbers did you get?

 

[farminkarman]

@jurchybald
Is the piston a flat-top? That chamber looks like an Echo.

 

[farminkarman]

What stock timing numbers did you get?

He posted them here:

Post in thread '400.1 first impression'

Jun 23, 2025

Would like to see some of the rest of the "picture" so to speak, like the timing numbers and squish as it comes from the factory, along with the gasket thickness and extension gap to case measurement before trying to develop a plan of attack with the cylinder extension of this saw.
Some possible machining ideas come to mind but are hardly worth mentioning without the benefit of having an example in hand to ascertain just what can be done successfully and to the betterment of the machine.

Here you go

• jurchybald

• 

 

[Sloughfoot]

He posted them here:

Post in thread '400.1 first impression'

Jun 23, 2025

Would like to see some of the rest of the "picture" so to speak, like the timing numbers and squish as it comes from the factory, along with the gasket thickness and extension gap to case measurement before trying to develop a plan of attack with the cylinder extension of this saw.
Some possible machining ideas come to mind but are hardly worth mentioning without the benefit of having an example in hand to ascertain just what can be done successfully and to the betterment of the machine.

Here you go

• jurchybald

• 

Gracias. Don't know much about stratos but the rest of those numbers look pretty solid. Is 80 with a strato the same as 80 with a nonstrato?

 

[jurchybald]

@jurchybald
Is the piston a flat-top? That chamber looks like an Echo.

Flat top

 

[ferris]

 

[ferris]

What do u guys think is the reason for the better gains compared to only opening up the original outlet?
Is it the bigger size or the reduced volume?

 

[lehman live edge slab]

What do u guys think is the reason for the better gains compared to only opening up the original outlet?
Is it the bigger size or the reduced volume?

No idea but I hope muffler mods with side outlets will gain as much or close because I personally despise any wide open front muffler mod because of how obnoxiously loud they usually are.

 

[Duane(Pa)]

What do u guys think is the reason for the better gains compared to only opening up the original outlet?
Is it the bigger size or the reduced volume?

Have you ever seen the exhaust outlet on a Stihl 260? It’s about the diameter of a pencil… I think restrictions are their go-to for reducing noise and emissions.

 

[Sloughfoot]

Doesn't the stock 400.1 muffler have an insert into the exhaust port?

 

[Duane(Pa)]

Yes

 

[Duane(Pa)]

Cover

 

[Sloughfoot]

Have you ever seen the exhaust outlet on a Stihl 260? It’s about the diameter of a pencil… I think restrictions are their go-to for reducing noise and emissions.

My attention to the video was divided, that insert removed?

 

[lehman live edge slab]

My attention to the video was divided. Was that insert removed?

No I think it’s fully stock back half with a flat plate bark box style replacement for front half of can that has the outlet on it. So it made the exhaust outlet huge but also reduced the can volume by 40-50% probably

 

[Sloughfoot]

No I think it’s fully stock back half with a flat plate bark box style replacement for front half of can that has the outlet on it. So it made the exhaust outlet huge but also reduced the can volume by 40-50% probably

Interesting. The larger outlet is to count for all the gains made, is my guess. Why not chop the insert, max out the exhaust port width and match the muffler to the port? <Serious question. I know just enough about porting to be dangerous

 

[bwalker]

What do u guys think is the reason for the better gains compared to only opening up the original outlet?
Is it the bigger size or the reduced volume?

I don't know, but the power curve was impressive. Very wide curve.

 

[sawmikaze]

Does the ms 400.1 still blow or is it ok now ?