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grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Thu Nov 15, 2007 6:14 am Post subject: 2 stroke vs 4 stroke

What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 stroke should be more reliable especially the piston port engine because it only had a few moving parts to fail. Pistons, crank and rods and thats it. 4 strokes have many more parts that could lead to an engine failure.



So why  are engine outs more common with 2 strokes? Why is there more maintenance involved with the 2 cycle?



What oil do you guys use in your rotax engines? I know a lot of people use penzoil air cooled 2 cycle oil.

Is anyone using the blue max in there 503? I like the idea of mixing it 100:1 because it reduces the carbon build up. I talked to a guy who ran it in a hirth for 100hrs with no problems. He said there was hardly any carbon build up running it 100:1.

here is a link to the oil

http://www.recpower.com/blumax.htm

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Thu Nov 15, 2007 6:43 am Post subject: 2 stroke vs 4 stroke

Don't follow the siren song of 100:1 oil mixes, it's just not enough oil 

for an aircraft application. I tried it years ago, the Rotax survived, 

but I really didn't like listening to the engine rattle as I babied it 

back to the field. Added enough oil to the premix to get it back to 50:1 

and the rattle went away. Lesson learned...



Been running Phillips Injex in Rotax 2-strokes for 24 years and more 

than 1200 hours with no problems, very little carbon build up, and rings 

that easily go more than 100 hours without sticking. Jet your Bing so 

that cruise power gives egt's between 1075 and 1125 and Injex will give 

you almost no carbon buildup.



Richard Pike

MKIII N420P (420ldPoops)



grantr wrote:

 	  Quote: 	
		   



 What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 stroke should be more reliable especially the piston port engine because it only had a few moving parts to fail. Pistons, crank and rods and thats it. 4 strokes have many more parts that could lead to an engine failure.



 So why  are engine outs more common with 2 strokes? Why is there more maintenance involved with the 2 cycle?



 What oil do you guys use in your rotax engines? I know a lot of people use penzoil air cooled 2 cycle oil.

 Is anyone using the blue max in there 503? I like the idea of mixing it 100:1 because it reduces the carbon build up. I talked to a guy who ran it in a hirth for 100hrs with no problems. He said there was hardly any carbon build up running it 100:1.

 here is a link to the oil

 http://www.recpower.com/blumax.htm





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146190#146190

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

jindoguy(at)gmail.com
Guest

Posted: Thu Nov 15, 2007 7:10 am Post subject: 2 stroke vs 4 stroke

4 stroke engines, in general, have pressure oiling systems, 2 strokes

have to rely on the oil being either direct injected into the engine

or being premixed with the gas.

I've used BlueMax oil in a Hirth I had in the shop last summer, but

not enough to make a statistical blip.

The primary killer of 2 strokes is running too lean. Remember how it's

oiled? Also faulty crank seals don't leak oil out, like a 4 stroke,

they leak air in, leaning the mixture. If you run a 4 stroke lean, it

won't like it, beyond a narrow range that is, but the quantity of oil

delivered to the piston skirt and bearings remains the same.

There's also the issue of proper storage. A 4 stroke, with good

quality oil in it, had that oil splashed all over its innards as it

ran. The 2 stroke has its oil delivered in a solvent. To store it

properly (Rotax says any time over 30 days of inactivity) you need to

run a can of misting oil, first through the carb until the extra oil

kills the engine, then into the combustion chamber via a spark plug

hole.

Last there is operating temperature. My HKS has a max head temp spec

of 338 degrees, the 912 is 300 continuous, 325 for short periods,

after which the heads must be Rockwell tested for proper hardness. The

447 I just broke in has a max CHT of 480 degrees, and regularly hit

close to 400 in climb.

These certainly aren't all the differences that effect engine

longevity, but its a start.



Rick



On Nov 15, 2007 8:14 AM, grantr <grant_richardson25(at)yahoo.com> wrote:

 	  Quote: 	
		   



 What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 stroke should be more reliable especially the piston port engine because it only had a few moving parts to fail. Pistons, crank and rods and thats it. 4 strokes have many more parts that could lead to an engine failure.



 So why  are engine outs more common with 2 strokes? Why is there more maintenance involved with the 2 cycle?



 What oil do you guys use in your rotax engines? I know a lot of people use penzoil air cooled 2 cycle oil.

 Is anyone using the blue max in there 503? I like the idea of mixing it 100:1 because it reduces the carbon build up. I talked to a guy who ran it in a hirth for 100hrs with no problems. He said there was hardly any carbon build up running it 100:1.

 here is a link to the oil

 http://www.recpower.com/blumax.htm





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146190#146190

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Nov 15, 2007 8:27 am Post subject: Re: 2 stroke vs 4 stroke

Another consideration in 2 vs 4 stroke longevity is the fact that the 2 stroke revs higher along with all the inherent stresses and vibrations.



Also, the 2 stroke fires once per revolution as opposed to the 4 stroke firing every 2nd revolution so there is more time for the heat to distribute to the cooling fins in a 4 stroke.



2 strokes lead a hard life by their very nature and they have to be treated with extra care to ensure they last and perform properly.



The advantages are high power output at minimum weight compared to most other practical solutions.



Here is a review of the Penzoil product:

http://www.ultralightnews.com/features/oiltest.htm



and this describes how 2 stroke oil works:

http://www.ultralightnews.com/features/oilworks.htm



The above articles also describe why a synthetic oil at 100:1 is not a good choice for 2 stroke air cooled engines.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Nov 15, 2007 8:42 am Post subject: 2 stroke vs 4 stroke

Regarding the argument of 2 stroke engines versus 4 strokes, I read an article once that did a very deep and scientific explanation of why 2 strokes are short lived, when compared to 4 stroke engines.



  Including all the items mentioned by Rick, there was a huge difference that has to do with the velocity of the moving parts.  Yes, 2 strokes produce prodigious amounts of power, but the friction of these internal surfaces is incredibly higher than the comparable frictions a 4 stroke sees.  And when you add in the sensitivities of oiling that the 2 stroke has, (proper ratio, no suction leaks, etc.), the 4 stroke usually lasts many times over the life of a 2 stroke engine.



  BUT!!  As always, there is a but.  In this comparison, one could conclude a 4 stroke engine is better, but that isn't a a complete win for the 4 stroke.  A 2 stroke will generally produce significantly more power for a given weight.  A 4 stroke could only dream of the power output of a typical 2 stroke, and this is because of the obvious; a 4 stroke engine only has 1/2 the opportunity to produce power that the 2 stroke has.  Every second rotation of the crankshaft a 2 stroke is working on a power stroke, whereas a 4 stoke engine only sees this at every 4 revolutions.



  Another limiting factor of the 2 stroke engine is its size.  Recall a moment ago where we stated the high velocity of the internal moving parts of a 2 stroke.  As everyone knows, force is increased with the square of the velocity.  In other words, as a 2 stroke gets bigger, the higher speed of the parts becomes a huge detriment to keeping the engine together.   A 100 cc engine can easily spin 8000 RPM.  A 1000 cc will have more difficultly being able to spin 8000 RPM's....and stay together.  A 3000 cc 2 stroke engine could only spin 8000 RPM for only a few seconds.  As the piston's mass increases, so does its momentum.  And the bigger the piston, the less interested it is in stopping, and turning around and going the other direction.  Therefore, you would have to increase the size (and mass) of the rod, to handle this huge piston.  But a more massive rod is less likely to be changing directions, just like the more massive piston.  And what you have is vicious cycle, the engine is held to being relatively "small", due to the physics of velocity of the moving parts.



This is explained by the formula:      KE =  1/2 x mass x velocity x velocity   or    KE = 1/2mV(sqrd)



KE equals Kinetic Energy, m means mass of the item that's moving, and v means the velocity of the moving mass.



  Obviously, as a piston's velocity is increased, the Kinetic Energy (KE) goes WAY up!!!  

Example:   Let's say we have a 1 kg piston moving up and down at 75 cm/sec, therefore we would get:



KE = 1/2 x 1 kg x 75 cm/sec (squared),......which equals.........5,625 Kinetic Units



But, let's double the velocity of our piston to 150 cm/sec, and see what this produces:



We then get:  KE = 1/2 X 1 kg x 150 cm/sec x 150 cm/sec.......which equals........22,500 Kinetic Units



Wow!  By simply doubling the pistons velocity, the Kinetic Energy quadrupled!!   And all this extra energy is focused on the connecting rod.  If you keep increasing the velocity, or even the mass, for that matter, there will be a point where the connecting rod will no longer be able to contain this energy.



  This scenario is classily displayed at the "races", when some fire breathing dragster blows an engine.  He usually "throws a rod", where the rod couldn't keep up with the kenetic energy of the pistons spinning at 9 grand!!!



  Anyway, that's what I was thinking.           Mike Welch



  

_________________________________________________________________

herbgh

Joined: 10 Jan 2006
Posts: 145

Posted: Thu Nov 15, 2007 9:14 am Post subject: 2 stroke vs 4 stroke

2 stroke reliability.?? 



   two or three  things imho...Lack of operator knowledge...and

lubrication.... striving for good fuel consumption equals less

lubrication... a common thread on 2 cycle lists is fuel burn... You have

to put some fuel through to get good lubrication...



   My notion...decarbon frequently...mix the oil at a low ratio(50 to 1) 

and run the pee out of them...and when they hit 5 to 600 hours...sell

them on ebay as low or unknown time!!   And there in lies the other

problem....used and unknown time engines....No one should complain about

a bad 2 stroker if they buy used!!!    Herb 



  

On Thu, 15 Nov 2007 06:14:56 -0800 "grantr"

<grant_richardson25(at)yahoo.com> writes:

 	  Quote: 	
		   

 <grant_richardson25(at)yahoo.com>

 

 What makes the 2 stroke less reliable than the 4 stroke? In theory 

 the 2 stroke should be more reliable especially the piston port 

 engine because it only had a few moving parts to fail. Pistons, 

 crank and rods and thats it. 4 strokes have many more parts that 

 could lead to an engine failure.

 

 So why  are engine outs more common with 2 strokes? Why is there 

 more maintenance involved with the 2 cycle?

 

 What oil do you guys use in your rotax engines? I know a lot of 

 people use penzoil air cooled 2 cycle oil.

 Is anyone using the blue max in there 503? I like the idea of mixing 

 it 100:1 because it reduces the carbon build up. I talked to a guy 

 who ran it in a hirth for 100hrs with no problems. He said there was 

 hardly any carbon build up running it 100:1.

 here is a link to the oil

 http://www.recpower.com/blumax.htm

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=146190#146190

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Nov 15, 2007 9:28 am Post subject: Re: 2 stroke vs 4 stroke

Mike, not to pick nits but a 2 stroke has an induction of fuel & expulsion of exhaust on one stroke (180 degrees) and compression and ignition on the other stroke(another 180 degress).



and those 2 strokes added together = 360 degrees of crank rotation and is 1 rev ....therefore the 2 stroke produces power every rev as opposed to the 4 stroke producing power on every 2nd rev.

The 4 stroke has the following strokes(180 degrees):

1) Fuel Valve 1 opens letting in fuel/air on doward stroke.

2) Valve 1 closes and compresses fuel/air on upward stroke.

3) Fuel/air ignition on downward stroke, both valves closed.

4) Exhaust valve 2 opens and exhaust expelled on upward stroke, and then closes valve 2.



Cycle is complete after 4 x 180 degrees = 720 degrees = 2 revs

Here is a 4 stroke animation: http://www.keveney.com/otto.html



The 2 stroke is a bit harder to explain since multiple things are occuring at the ports both above and below the piston at the same time, so here is an animation: http://www.keveney.com/twostroke.html



The valve that lets in fuel in our engines is the piston skirt clearing the fuel intake port and sucking the fuel into the crank case.



In some Rotaxes I think there are reed valves performing the function of the intake one way(in only) valve.



The fuel in the crank case is also what lubricates and cools the engine parts internally, requires the premix oil to do its thing here.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Nov 15, 2007 9:51 am Post subject: Re: 2 stroke vs 4 stroke

 	  grantr wrote: 	
		  

What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 stroke should be more reliable especially the piston port engine because it only had a few moving parts to fail. 

	




2 Strokes are less reliable than 4 strokes, that is just a fact of life.   Don't get hung up on the theory, just recognize the real world results for what they are.  For a 2 stroke to run reliably it must have near perfect fuel air mixture AND prop loading, and there is the problem.  In real life, perfection rarely exists, and it is ever harder to keep perfection of these things in hundreds of hours of aircraft use.  Many companies have tried making 2 stroke engines reliable enough for certified aircraft, and every project has been abandoned.  If a bunch of engine experts and companies with lots of resources were unable to make a 2 stroke more reliable on airplanes than 4 strokes, chances are almost zero that you will be able to.

Bottom line is if you want a reliable engine that is least likely to quit then its a no brainier, fly a 4 stroke.    



If you can not afford a 4 stroke, and have no other option then to fly with a 2 stroke, do yourself a favor and read this article.  Its short, and gives you really good useful, real world information (not a bunch of theory ) on how to keep your 2 stroke running as reliably as possible.  



http://curedcomposites.netfirms.com/twostroke.html



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Nov 15, 2007 10:19 am Post subject: 2 stroke vs 4 stroke

Ray, 



  I knew that.  I just wanted to see if anyone was paying attention. he he he

  After I sent the email, I thought "you know, someone is going to point out that I described this wrong."

  But you have to admit the rest of the email sounded fairly scinetific for a dopey basterd.      Mike

 	  Quote: 	
		   Subject: Re: 2 stroke vs 4 stroke

 From: jb92563(at)yahoo.com

 Date: Thu, 15 Nov 2007 09:28:30 -0800

 To: kolb-list(at)matronics.com



 



 Mike, not to pick nits but a 2 stroke has an induction of fuel & expulsion of exhaust on one stroke (180 degrees) and compression and ignition on the other stroke(another 180 degress).



 and those 2 strokes added together = 360 degrees of crank rotation and is 1 rev ....therefore the 2 stroke produces power every rev as opposed to the 4 stroke producing power on every 2nd rev.

 The 4 stroke has the following strokes(180 degrees):

 1) Fuel Valve 1 opens letting in fuel/air on doward stroke.

 2) Valve 1 closes and compresses fuel/air on upward stroke.

 3) Fuel/air ignition on downward stroke, both valves closed.

 4) Exhaust valve 2 opens and exhaust expelled on upward stroke, and then closes valve 2.



 Cycle is complete after 4 x 180 degrees = 720 degrees = 2 revs

 Here is a 4 stroke animation:



 The 2 stroke is a bit harder to explain since multiple things are occuring at the ports both above and below the piston at the same time, so here is an animation:



 The valve that lets in fuel in our engines is the piston skirt clearing the fuel intake port and sucking the fuel into the crank case.



 The fuel in the crank case is also what lubricates and cools the engine parts internally, requires the premix oil to do its thing here.



 --------

 Ray

 Riverside County, CA



 Do Not Archive





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146230#146230






	


_________________________________________________________________

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jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Nov 15, 2007 10:21 am Post subject: Re: 2 stroke vs 4 stroke

Very timely Mike....Thanks for the article.



I am just trying to tune my Cuyuna UL II-02 and this info has come at just the right time for me to do a proper job of tuning.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Thu Nov 15, 2007 10:42 am Post subject: 2 stroke vs 4 stroke

Which is exactly why I like to cruise my 582 as close to 5,000 rpm as I 

can get it. Good synopsis.



Richard Pike

MKIII N420P (420ldPoops)



Mike Welch wrote:

 	  Quote: 	
		   





   Regarding the argument of 2 stroke engines versus 4 strokes, I read an article once that did a very deep and scientific explanation of why 2 strokes are short lived, when compared to 4 stroke engines.



   Including all the items mentioned by Rick, there was a huge difference that has to do with the velocity of the moving parts.  Yes, 2 strokes produce prodigious amounts of power, but the friction of these internal surfaces is incredibly higher than the comparable frictions a 4 stroke sees.  And when you add in the sensitivities of oiling that the 2 stroke has, (proper ratio, no suction leaks, etc.), the 4 stroke usually lasts many times over the life of a 2 stroke engine.



   BUT!!  As always, there is a but.  In this comparison, one could conclude a 4 stroke engine is better, but that isn't a a complete win for the 4 stroke.  A 2 stroke will generally produce significantly more power for a given weight.  A 4 stroke could only dream of the power output of a typical 2 stroke, and this is because of the obvious; a 4 stroke engine only has 1/2 the opportunity to produce power that the 2 stroke has.  Every second rotation of the crankshaft a 2 stroke is working on a power stroke, whereas a 4 stoke engine only sees this at every 4 revolutions.



   Another limiting factor of the 2 stroke engine is its size.  Recall a moment ago where we stated the high velocity of the internal moving parts of a 2 stroke.  As everyone knows, force is increased with the square of the velocity.  In other words, as a 2 stroke gets bigger, the higher speed of the parts becomes a huge detriment to keeping the engine together.   A 100 cc engine can easily spin 8000 RPM.  A 1000 cc will have more difficultly being able to spin 8000 RPM's....and stay together.  A 3000 cc 2 stroke engine could only spin 8000 RPM for only a few seconds.  As the piston's mass increases, so does its momentum.  And the bigger the piston, the less interested it is in stopping, and turning around and going the other direction.  Therefore, you would have to increase the size (and mass) of the rod, to handle this huge piston.  But a more massive rod is less likely to be changing directions, just like the more massive piston.  And what you have is vicious cycle, the en!

  gine is held to being relatively "small", due to the physics of velocity of the moving parts.



 This is explained by the formula:      KE =  1/2 x mass x velocity x velocity   or    KE = 1/2mV(sqrd)



 KE equals Kinetic Energy, m means mass of the item that's moving, and v means the velocity of the moving mass.



   Obviously, as a piston's velocity is increased, the Kinetic Energy (KE) goes WAY up!!!  

 Example:   Let's say we have a 1 kg piston moving up and down at 75 cm/sec, therefore we would get:



 KE = 1/2 x 1 kg x 75 cm/sec (squared),......which equals.........5,625 Kinetic Units



 But, let's double the velocity of our piston to 150 cm/sec, and see what this produces:



 We then get:  KE = 1/2 X 1 kg x 150 cm/sec x 150 cm/sec.......which equals........22,500 Kinetic Units



 Wow!  By simply doubling the pistons velocity, the Kinetic Energy quadrupled!!   And all this extra energy is focused on the connecting rod.  If you keep increasing the velocity, or even the mass, for that matter, there will be a point where the connecting rod will no longer be able to contain this energy.



   This scenario is classily displayed at the "races", when some fire breathing dragster blows an engine.  He usually "throws a rod", where the rod couldn't keep up with the kenetic energy of the pistons spinning at 9 grand!!!



   Anyway, that's what I was thinking.           Mike Welch



   

 _________________________________________________________________

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ElleryWeld(at)aol.com
Guest

Posted: Thu Nov 15, 2007 11:04 am Post subject: 2 stroke vs 4 stroke

While the list is on an engine  subject  who is running a Jabaru Engine which model and How do you like the preformance and Have you got any pictures of your Setup 

  

 Still pondering other engines 

  

 Ellery Building MK3Xtra 

  

 do not archive





  [quote][b]

d-m-hague(at)comcast.net
Guest

Posted: Thu Nov 15, 2007 2:25 pm Post subject: 2 stroke vs 4 stroke

At 09:14 AM 11/15/2007, grantr wrote:

 	  Quote: 	
		  



What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 

stroke should be more reliable especially the piston port engine because 

it only had a few moving parts to fail. Pistons, crank and rods and thats 

it. 4 strokes have many more parts that could lead to an engine failure.



So why  are engine outs more common with 2 strokes? Why is there more 

maintenance involved with the 2 cycle?



What oil do you guys use in your rotax engines? I know a lot of people use 

penzoil air cooled 2 cycle oil.

Is anyone using the blue max in there 503? I like the idea of mixing it 

100:1 because it reduces the carbon build up. I talked to a guy who ran it 

in a hirth for 100hrs with no problems. He said there was hardly any 

carbon build up running it 100:1.

here is a link to the oil

http://www.recpower.com/blumax.htm





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=146190#146190




	


--

  But I don't have an "any key" on my computer!

d-m-hague(at)comcast.net
Guest

Posted: Thu Nov 15, 2007 2:39 pm Post subject: 2 stroke vs 4 stroke

At 09:14 AM 11/15/2007, grantr wrote:



 	  Quote: 	
		  What makes the 2 stroke less reliable than the 4 stroke? In theory the 2 

stroke should be more reliable especially the piston port engine because 

it only had a few moving parts to fail. Pistons, crank and rods and thats 

it. 4 strokes have many more parts that could lead to an engine failure.



So why  are engine outs more common with 2 strokes? Why is there more 

maintenance involved with the 2 cycle?


	


The primary reason is the way that 2-strokes are lubricated.  Yes, as 

others have pointed out, they're more highly stressed since they get more 

power out of the same size package, but modern metallurgy and materials 

technology means that actual mechanical failures (not related to 

lubrication) are rare.



The lubrication, of course, is dependent on the fuel/air mixture.  Assuming 

there's the proper amount of oil mixed with the fuel (or injected in), 

having the right fuel/air mixture is critical.  Too little (too lean) and 

the engine seizes, or bearings fail, or it runs hot... and the engine 

quits.  Too much (too ruch) and it carbons up, eventually shorting out the 

spark plug... and the engine quits.  Even if it's adjusted right initially, 

air leaks (bearing seals, gaskets, and carburetor boots) can make it run 

lean.  Furthermore, the optimum mixture point changes with the seasons and 

weather conditions.



Here's an interesting thought:  Many people remove the oil injection system 

from their Rotax engines, fearing the failure of the injection pump.  I'd 

like to see statistics regarding the relative reliability of the same model 

engine with and without oil injection.  At least with oil injection, you 

always have the intended amount of oil per revolution regardless of 

fuel/air mixture.



Another thought:  If you _do_ have oil injection, seems it would be 

possible to inject at least part of it into the bearings, getting the 

benefit of a 4-stroke's pressurized oil system to at least the lower end... 

from whence the oil would find its way into the crankcase to mix with the 

fuel as it does on any 2-stroke.



Still another thought:  I have long believed that electronic fuel injection 

(EFI) could be a major improvement to 2-stroke reliability.  By taking the 

mixture adjustment out of the operator's hands, it should be possible to 

eliminate the problems from ignorant adjustments, or failure to make a 

needed seasonal adjustment.  Or, perhaps not even the complexity of fuel 

injection, just an automatic mixture controlled carburetor, with feedback 

from an exhaust oxygen sensor sensing the ratio (I know that O2 sensors are 

problematic with oil in the fuel but it shouldn't be insurmountable).



                                 -Dana

--

  But I don't have an "any key" on my computer!

d-m-hague(at)comcast.net
Guest

Posted: Thu Nov 15, 2007 2:40 pm Post subject: 2 stroke vs 4 stroke

At 12:51 PM 11/15/2007, JetPilot wrote:

 	  Quote: 	
		  -

If you can not afford a 4 stroke, and have no other option then to fly 

with a 2 stroke, do yourself a favor and read this article.  Its short, 

and gives you really good useful, real world information (not a bunch of 

theory ) on how to keep your 2 stroke running as reliably as possible.



http://curedcomposites.netfirms.com/twostroke.html


	


That's a good article.  One thing I found particularly interesting, the 

point about long partial power descents.  I've always been leery about long 

idling descents, partially from concern about shock cooling, but also for 

fear of the engine loading up and quitting.  I have to think about that one.



                                 -Dana

--

  But I don't have an "any key" on my computer!

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Nov 15, 2007 2:53 pm Post subject: Re: 2 stroke vs 4 stroke

There are fuel injected 2 strokes available here:

http://www.recpower.com/f23.htm

I agree these must be more reliable and probably worth the extra cost.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Nov 15, 2007 2:58 pm Post subject: Re: 2 stroke vs 4 stroke

I also found this document that guides you through jetting and proping your 2 stroke properly and the relationship between the EGT, CHT and Static RPM.



Good info and still points out the descending under mid power issue for 2 strokes due to inadvertent leaning through unloading the prop in a shallow dive.

Principles Of 2 stroke jetting.doc

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Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Thu Nov 15, 2007 3:24 pm Post subject: 2 stroke vs 4 stroke

Yep, that is a pretty good document.

Somebody got it off my web page, here:

http://www.bcchapel.org/pages/0003/pg11.htm



Richard Pike

MKIII N420P (420ldPoops)

jb92563 wrote:

 	  Quote: 	
		   



 I also found this document that guides you through jetting and proping your 2 stroke properly and the relationship between the EGT, CHT and Static RPM.



 Good info and still points out the descending under mid power issue for 2 strokes due to inadvertent leaning through unloading the prop in a shallow dive.



 --------

 Ray

 Riverside County, CA



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 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146317#146317





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_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

d-m-hague(at)comcast.net
Guest

Posted: Thu Nov 15, 2007 3:51 pm Post subject: 2 stroke vs 4 stroke

At 05:53 PM 11/15/2007, jb92563 wrote:



 	  Quote: 	
		  There are fuel injected 2 strokes available.



I agree these must be more reliable and probably worth the extra cost.


	


Well, Rotax oughta get with the program!



                                 -Dana

--

  Censorship: The reaction of the ignorant to freedom.

jindoguy(at)gmail.com
Guest

Posted: Thu Nov 15, 2007 5:10 pm Post subject: 2 stroke vs 4 stroke

The question of fuel injection came up at the Rotax Service Center

classes at Lockwood this last spring. Eric Tucker was asked, why it

wasn't used by Rotax. None available that meets Rotax reliability

standards.

I spent two years around a group of Hirth fuel injected engines

installed in MiniMaxes at Arlington, WA. We were flying a Kasperwing

at the time, probably the most weather finicky aircraft ever built,

but that's another discussion. At any rate, we would come out an a

beautiful day and run 14 gallons of fuel through the little Zenoah

over the course of the day. The Minimaxes would come out to the flight

line, get started and their tuning would get fiddled with for awhile

(I really don't know what else to call it, since it never resulted in

anything more than a circuit around the pattern), then the owners

would retire to the picnic benches for the remainder of the day.

Eric Tucker has more experience with 2 strokes than all the people on

this list put together. I trust his judgment. You can do as you wish.



Rick



On Nov 15, 2007 4:53 PM, jb92563 <jb92563(at)yahoo.com> wrote:

 	  Quote: 	
		   



 There are fuel injected 2 strokes available.



 I agree these must be more reliable and probably worth the extra cost.





 --------

 Ray

 Riverside County, CA



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