stratocharge motor and muffler mods

[Kneejerk Bombas]

Why not just block off the strato ports?

 

[JUDGE1162]

Why not just block off the strato ports?

Then the mix would be too rich, the fuel/air mix is set up for the cylinder to be ful of fresh air already.

 

[Lakeside53]

Yes, way way too rich - you'd need to rebuild the carb jetting... maybe even different carb (venturi size etc). And then you are back to up to 30% HC loss etc etc..

Just disconnect the linkage on the air-intake - you'll see what happens real quick..

 

[timberwolf]

Looks like them air ports are just ready made boost ports, just need a way to feed them from the carb, wich would likely need to be upsized a bit.

 

[Lakeside53]

I figure connect a second carb to the air intake manifold...

 

[eyolf]

thanks for posting, Lakeside.

I'm reasoning that I went wrong by assuming there would be an rpm range where the chainsaw can silencer's back pressure actually worked as planned...backpressure holding back fresh mix, while letting enough pressure out to still allow some performance. I knew that opening up modern saw mufflers often results in a perf increase, but I think we just saw a glimpse of the fact that these modern cans don't work at all in any range and are a huge detraction.

I'm impressed with the sound levels (not too loud) with the Husky new generation saws...how about the 441? Modding a muffler is OK, until you have to work in a developed area, esp. when you like starting right away in the morning. Most people will put up with a regular saw at 7:00 am, but will get cranky at a modded unit.

 

[JUDGE1162]

Muffler Mods on any saw used in a developed area can be an use, I was working with a stihl chop saw with a normal muffer and got a citation for violating the local noise ordance. SO a mod muffler would be even louder.


But boy do they sound cool

 

[Kneejerk Bombas]

Yes, way way too rich - you'd need to rebuild the carb jetting...
Just disconnect the linkage on the air-intake - you'll see what happens real quick..

So the carb jetting pumps more gas than a 440? That would mean greater fuel consumption, wouldn't it?
And can't you just screw the jet closed if it's too rich?

 

[JUDGE1162]

So the carb jetting pumps more gas than a 440? That would mean greater fuel consumption, wouldn't it?
And can't you just screw the jet closed if it's too rich?

I am far from a motor expert but since I have one of these saw I have spent a ton of time asking questions and researching them, from what I can tell the ports are set up so there is an air with no fuel port which opens first and clears the cylinder of burnt exhaust gases, then a second port opens with is a very rich mix of fuel and air that mixes with the air already in the cylinder to make the proper fuel/air ratio mix. If you block the air only port there would not be enough air in the cyclinder and the fuel/air ratio would be too rich. Yes you could thin out the fuel/air mix but then there would be much less fuel in the cyclinder compare if you left it alone and you would lose power.


It is new technology there are pros and cons, I think it is very simular to new cars, it was a lot easier to trick out, modify, an older car then it is to modify a newer car, however new cars have some pretty cool upgrades that get a whole lot more power out of smaller motors. A 2006 car with the same size motor is a whole faster then a 1970 or even a 1990 car. This is due to fuel injection, cold air intakes, multi values, overhead cams, computer controls, by the same token they are cleaner running, more fuel effiect, and safer, but also much harder to work on.


And like it or not these Stratocharged motors seem to be the future of ALL saws, and yes doing saw mods will be much harder just like doing car mods on newer cars, unless we get lucky and like in cars, we can get aftermarket upgrades that are purely bolt on or swap out. I have spoken to a few saw mod people and have been told that modifying these new motors is a lot harder and a lot more comlicated then the older saws. I guess I am just lucky since without trying I now own 2 stratocharged saws, and in both case modifications are either near impossible like with my 455 Rancher or are very hard and pricely to do like on my new 575XP.


SO, I hate to be the bearer of Bad news but everyones favorite pro-saw the 372 (the go to saw and in may peoples mind the best saw around) is being phased out. (I think in the USA it has already been phased out already) and replaced with the 575XP a stratocharged motor.

I spoke with a tech guy over at Husky and he said at least in the USA and EU countries that they will be replacing most saws with a newer version which will all use a Stratocharged motor to meet tougher and tougher EPA and EU2 emmison directive. The other option is like the new proto-type Makita, we will end up with 4 cycle saws.

 

[Lakeside53]

So the carb jetting pumps more gas than a 440? That would mean greater fuel consumption, wouldn't it?
And can't you just screw the jet closed if it's too rich?

Nope... it's not pumping "more gas" - the carb assumes a mixture where part of the air is via the air port. The main carb body delivers a mixture that is too rich and at lower air velocity.

As for "adjusting" - Carbs changed along time ago from full control to partial control of the mixture. Re-jetting and venturi changes might be required.

 

[Kneejerk Bombas]

Is the carb completely different from the 440?

 

[sawinredneck]

Yes Mike, it is completly different, the 441 looks like a two barrel carb, one is smaller than the other. The main one feeds the fuel, the smaller is the purge air.
Andy

 

[Lakeside53]

 

[JUDGE1162]

Lakeside53 thanks that is very cool it is always so much easier to just see what is going on and I am too chicken sh:censored: to pull my saw apart just to take a look.

Whats is that a carb from?


OK I have read on the web that one mod that can be do is to put in a larger carb, and clue if there is an easy swap out carb for either a 455 rancher or a 575XP?