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  #51  
Old 03-25-2013, 04:38 PM
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jkilov jkilov is offline
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Quote:
Originally Posted by birddseedd View Post
but if the engine no longer work to epa regulations are we not required by law to get back into spechs?
EPA certification is the manufacturer's thing.

This is not a car. You buy it and run it for 3000 hrs if it holds up.

But officially, you're not allowed to modify the emission related components (carbs, ports, mufflers, etc..) at any time.
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  #52  
Old 03-25-2013, 06:25 PM
lawnboy dan lawnboy dan is offline
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dolmar 4 strokes are robin engines
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  #53  
Old 03-25-2013, 06:28 PM
birddseedd birddseedd is offline
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Quote:
Originally Posted by jkilov View Post
EPA certification is the manufacturer's thing.

This is not a car. You buy it and run it for 3000 hrs if it holds up.

But officially, you're not allowed to modify the emission related components (carbs, ports, mufflers, etc..) at any time.
so no gas evaporators?
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  #54  
Old 03-25-2013, 11:08 PM
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JCLawn and more JCLawn and more is offline
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Quote:
Originally Posted by lawnboy dan View Post
dolmar 4 strokes are robin engines
Robin/subaru if I remember exactly. And wonderful engines.
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  #55  
Old 03-25-2013, 11:16 PM
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JCLawn and more JCLawn and more is offline
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Quote:
Originally Posted by jkilov View Post
By "old-ones" I meant pre-EPA 2-strokes. Pure Schnurle ported would be more accurate.

A 2-stroke engine is a design flaw in itself. Both intake and exhaust ports are open at the same time allowing fuel to short-cut directly to the muffler. The old 2-stroke could hence loose about 1/3 of it's fuel directly to the exhaust. This resulted in fuel consumption figures over 600 g/hphr and hydrocarbon emissions of 200 g/hphr, simple math.

However this fuel wasn't completely lost, since it evaporated it cooled the engine directly proportional to the heat being generated. Old 2-strokes were easy to start, responsive and fast to warm up, yet difficult to overheat and with great torque.

On the other hand all modern 2-strokes (2-mix, tornado, stato) and other fancy names use a lean-mix carburetor with various tricks (air plug, port block or resonator) to reduce the short-cutting effect and/or a catalytic muffler to burn off the rest.

Unfortunately, lean setting makes them "cold-blooded": hard to start when cold, anemic performance on warm-up yet very hot running afterwards. Those with catalytic mufflers also suffer from heat soak when turned off making them stubborn to restart immediately after.

Hence my preference the 4-stroke.
I tell you what my dolmar saw is the easiest 2 stroke engine I've ever started. My friends run sthil saw and they yank and yank trying to get them started. Mine starts 1st or 2nd pull every time. Heat wise not sure. I do know my dealer said they are the simplist 2-stroke motor on the market and that's why they went with them. I know my saw with the upgraded air kit can run in a burning building and that's why fire fighters like it. My shindi hedge trimmer is collest running 2 stroke I think I've ran and super easy to start. So I guess I wonder if what your saying is pretty much only applies to sthil and husky haha
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  #56  
Old 03-26-2013, 09:14 AM
birddseedd birddseedd is offline
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think there would be a market in rotary trimmers?
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  #57  
Old 03-26-2013, 10:20 AM
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JCLawn and more JCLawn and more is offline
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Id buy it. It also buy a trimmer with this engine on it http://www.youtube.com/watch?v=lc6jCGHj6Nc
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  #58  
Old 03-26-2013, 10:25 AM
birddseedd birddseedd is offline
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oh heck yea. tho i posted a video earlier of the guy making that engine. or at least one about the same size. i dont know if i would get a rotery trimmer tho. the engine isnt all that good. powerfull at first but burns up quick.
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  #59  
Old 03-26-2013, 10:32 AM
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JCLawn and more JCLawn and more is offline
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Quote:
Originally Posted by birddseedd View Post
oh heck yea. tho i posted a video earlier of the guy making that engine. or at least one about the same size. i dont know if i would get a rotery trimmer tho. the engine isnt all that good. powerfull at first but burns up quick.
ld be fun while it lasted. I really want my diesel trimmer though. I don't care if it weighs 100lbs and its back pack, I want one.
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  #60  
Old 03-26-2013, 03:55 PM
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Patriot Services Patriot Services is online now
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Quote:
Originally Posted by birddseedd View Post
oh heck yea. tho i posted a video earlier of the guy making that engine. or at least one about the same size. i dont know if i would get a rotery trimmer tho. the engine isnt all that good. powerfull at first but burns up quick.
How so? Mazda proved it for decades. The EPA did the rotary in, not the design.
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