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williamtsullivan(at)att.n
Guest

Posted: Wed Apr 02, 2008 2:36 am Post subject: 2 strokes

Cristal- I am in the same position as you. I bought a used Firestar with a 447 Rotax, and no papers. The former owner was very casual on his maintenance, and the aircraft is about 20 years old. I have been lurking on both the Kolb and Rotax lists for quite a while to get a handle on everything. I don't have any 2 stroke flight time, and only have about 6 hours flying time. I have had a lot of experience on 2 strokes in motorcycles, chain saws, and brush cutters, however. In 40 years, the only 2 stroke engine failure was a hole burned in a Yamaha piston- running a too hot plug in a dirt bike on the highway. Nobody told me to change to a colder plug for highway use. Any other trouble was old gas, or a poor gas mix. My advice, for what it's worth, is fresh gas, properly mixed, good and careful maintenance, careful preflight, use the List, and enjoy! Follow the guidelines for time at max rpm and CHT and there won't be any trouble. All the other stuff comes under "pilot  error".

    Hey Listers- did I miss anything?

   

  do not archive

                                                    Bill Sullivan

                                                    FS/KX/447

                                                     Windsor Locks, Ct.

 [quote][b]

cristalclear13

Joined: 19 Sep 2007
Posts: 363
Location: Southeast Georgia

Posted: Wed Apr 02, 2008 5:18 am Post subject: Re: 2 strokes

Thanks Bill.  You say properly mixed which brings up another question.  I have a 50:1 ratio and I use a two-gallon tank (I'm a weakling).  According to the calculation then I would need to mix approx. 5.12 oz of oil in with my two-gallons of gas.  A 2/3 cup measurement is 5.33.  Is there a more exact way of getting the correct ratio?

_________________
Cristal Waters
Kolb Mark II Twinstar Rotax 503 DCSI Sept 2007 - sold Sept 2012
Private Pilot Aug 2008
ELSA Repairman for N193Y April 2008
Rotax 2 stroke maintenance April 2009

Steve Boetto

Joined: 11 Jan 2006
Posts: 364

Posted: Wed Apr 02, 2008 6:38 am Post subject: 2 strokes

In a message dated 4/2/2008 8:22:07 A.M. Eastern Standard Time,  cristalclearwaters(at)juno.com writes:

  	  Quote: 	
		  A 2/3    cup measurement is 5.33.  Is there a more exact way of getting the    correct ratio? 	
  

 Cristal,  I mix fuel all the time.  The best method I have come  up with is:

  

 Buy a 6 gal can.

 put a whole pint of oil in

 fill with 6 gal at the gas station.

 set the 6 gal tank on the tailgate of the truck 

 (or set on a concrete block and rock the can forward to fill a 2.5 gal  tank)

 fill plane 2.5 gal at a time

  

 There are also some cans that you can pump pressure in and dispense the  fuel with a nozzle.

  	  Quote: 	
		  Steve

	


Create a Home Theater Like the Pros. Watch the video on AOL Home.

  [quote][b]

williamtsullivan(at)att.n
Guest

Posted: Wed Apr 02, 2008 7:10 am Post subject: 2 strokes

Cristal- I bought a "Ratio-rite" measure from Aircraft Spruce. Very easy to use. I would recommend using a five gallon can for mixing, and pour it into a 2.5 gallon for pouring. I have to do this because my gas tank is hard to get at, and a bad back won't let me lift the 5 gallon that high. Use an MR funnel- read instructions- to remove any water. It is also available at Aircraft Spruce. If you don't have their catalog, get one. It is a flyer's wish book. Also, get one from Lockwood for Rotax info. Pennzoil 2 stroke air-cooled oil is recommended, available from Aircraft Spruce. Good luck, be meticulous, and have confidence in that engine. Like John said- pilot error stops more engines than anything else. Same thing with any 2 stroke. 

                                                Bill Sullivan

                                               FS/KX/447

                                               Windsor Locks, Ct.



cristalclear13 <cristalclearwaters(at)juno.com> wrote:

  [quote][b]

ElleryWeld(at)aol.com
Guest

Posted: Wed Apr 02, 2008 9:03 am Post subject: 2 strokes

Wicks Aircraft supply sells a oil measuring  bottle  that I have always used if you dump in a gallon you fill the oil  bottle to the one gallon mark and dump it in that will makle sure you always use  the correct ammount of oil

  

         Ellery in  Maine

 do not archive

  

  

  In a message dated 4/2/2008 8:22:07 A.M. Eastern Standard Time,  cristalclearwaters(at)juno.com writes:

  	  Quote: 	
		  -->    Kolb-List message posted by: "cristalclear13"    <cristalclearwaters(at)juno.com>



Thanks Bill.  You say properly    mixed which brings up another question.  I have a 50:1 ratio and I use a    two-gallon tank (I'm a weakling).  According to the calculation then I    would need to mix approx. 5.12 oz of oil in with my two-gallons of gas.     A 2/3 cup measurement is 5.33.  Is there a more exact way of getting the    correct ratio?



--------

Cristal

Mark II    Twinstar





Read this topic online    here:



http://forums.matronics.com/viewtopic.php?p=174323#174323

	




Planning your summer road trip? Check out AOL Travel Guides.

  [quote][b]

olendorf

Joined: 06 Jul 2006
Posts: 140
Location: Schenectady, NY USA

Posted: Wed Apr 02, 2008 10:01 am Post subject: Re: 2 strokes

Boy, do you guys have a lot of money!  



I take the plastic containers that Crystal Light drink mix comes in. (It is made of HDPE.)  I put in the exact amount of oil necessary for 1 gal then mark it with a sharpie. Then I mark off 2, 3 and 4 gals. The bigger containers will go to 6 I think.  I keep this in the plane so I can measure on the go. It even comes with a snap on lid to keep it clean inside.



So If I stop to get gas and it comes out 3.5 gals I don't have to do math ( a mans gotta know his limits ). I just fill with oil to the halfway spot between 3 and 4 and dump it in.

_________________
Scott Olendorf
Original Firestar, Rotax 447, Powerfin prop
Schenectady, NY
http://sites.google.com/site/kolbfirestar/

knowvne(at)aol.com
Guest

Posted: Wed Apr 02, 2008 1:07 pm Post subject: 2 strokes

Guys Is a little too much ok??? That Â has got to be better than not quite enough....Â 

  

 

  Does this spell bad plugs and possible engine failure

  during that tank of gas???

  

 

  

 

  Must it be 50:1 Â exactly???? Â How Anal must we be with this????

  

 

  Thanks

  Mark

 

 

 --

gaman(at)att.net
Guest

Posted: Wed Apr 02, 2008 2:17 pm Post subject: 2 strokes

Keep in mind that 503s that have oil injection, vary the amount of oil ingested depending on throttle applied at the time.50 to 1 may be enough at full throttle,but more than needed at partial throttle.It may not be as critical as we make it An extra ounce in 5 gal doesn't seem too critical.Too much oil builds carbon,thats why oil injection is desirable.The total amount of oil used per 5 gal of gas is less than 50-1.



---

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Wed Apr 02, 2008 4:10 pm Post subject: Re: 2 strokes

 	  knowvne(at)aol.com wrote: 	
		  Guys Is a little too much ok??? That Â has got to be better than not quite enough....Â 

  

Does this spell bad plugs and possible engine failure during that tank of gas???

 

Must it be 50:1 Â exactly???? Â How Anal must we be with this????

  

Thanks

Mark

	




Actually, this was a topic about 21 years ago. 2-stroke engines are very fussy as it's been discussed. Measuring oil is part of being fussy. 6-gallons requires 15.4 ounces of oil not 16 oz. One would think more oil means better lubrication. Not so with a 2-stroke. Too much oil is worse than not enough because it can lead to stuck rings when it fries into them. My 2-stroke has been reliable because I make sure it gets the correct amount of oil (premixed 447) and I use synthetic oil. There's one other thing I do, but I can't discuss it here as it's too controversial (I've been doing it for many years).



Ralph

_________________
Ralph B

Kolb Kolbra 912uls
N20386
550 hours

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Wed Apr 02, 2008 5:12 pm Post subject: Re: 2 strokes

There is a better source (in my opinion) for Pennzoil Air-Cooled oil, at least if you live in the NE part of the USA. Oil-store.com is located near Pittsburgh, PA so the shipping cost of a case/box of oil is not bad to Buffalo. If you like their price ask them to check the shipping cost to your zip code before you order.



Question related to 2-stroke oil mixing:

Is the 50:1 ratio in terms of volume or weight? Since gasoline weighs 6 lb. per US gallon and oil weighs (I think) 7.5 lb. per gallon there would be a different result if mixed by weight or by volume. I've been using fluid ounces (which a volume measurement) and have not had any problems but not sure which is "correct".

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

williamtsullivan(at)att.n
Guest

Posted: Wed Apr 02, 2008 6:10 pm Post subject: 2 strokes

Thom- All the 2 stroke mixes are by volume.

   

  do not archive

                                            Bill Sullivan

                                            FS/KX/447

                                            Ct.

 [quote][b]

pj.ladd(at)btinternet.com
Guest

Posted: Thu Apr 03, 2008 12:50 am Post subject: 2 strokes

A 2/3  cup measurement is 5.33.  Is there  a more exact way of getting the  correct ratio?>>

  

 Seems to be making heavy weather of a fairly simple  operation. For my 503 with a 50/1 mix I put half a litre into a plastic barrel  which holds 25 litres. I fill the barrel at the garage pump. The petrol  going in mixes the oil thoroughly without messing about shaking and rocking in a  separate container. I pump straight into the plane. It is not an exact science  and if the proportions are roughly correct there will be no trouble. At least I  have never had any. The  25 litre barrel was just the right size for  strapping in the back seat of my Challenger without fouling the rear  stick.

  

 Cheers

  

 Pat

 

 



   [quote][b]

cristalclear13

Joined: 19 Sep 2007
Posts: 363
Location: Southeast Georgia

Posted: Thu Apr 03, 2008 4:43 am Post subject: Re: 2 strokes

Maybe some of you misunderstood.  I wasn't trying to start a thread about HOW exact our measurements have to be or what size can I should use (My 2 gallon can works just fine for me - it's light and I can easily shake it up after I put the oil in with the gas.  I don't care if I have to use several two-gallon cans to fill up.  I don't plan to go far from home.)  I simply wanted to know if there was a better way to measure it than using a 2/3 cup measuring cup from my kitchen (and no, I'm not using that same cup to make my chocolate chip cookies afterwards).  Bill answered my question.  (Thanks!)  I see the "Ratio-rite" cup is only about 4 bucks in the Spruce catalog and they also sell a lid so that it'll stay clean inside and I won't have to wipe it out risking getting little pieces of "stuff" in it.

_________________
Cristal Waters
Kolb Mark II Twinstar Rotax 503 DCSI Sept 2007 - sold Sept 2012
Private Pilot Aug 2008
ELSA Repairman for N193Y April 2008
Rotax 2 stroke maintenance April 2009

Wade Lawicki

Joined: 27 May 2007
Posts: 31
Location: Nashville Tn.

Posted: Thu Apr 03, 2008 5:41 am Post subject: Re: 2 strokes

Thousands of hours on Rotaxs at our hangar, always mix 16oz into 6 gal cans. never a carbon problem. but its only been 20 years so I`m probably due.

                           Fly Safe,

                                        Wade



do not archive

_________________
Fly Safe! Wade
Nashville Tn.
FS 2

knowvne(at)aol.com
Guest

Posted: Thu Apr 03, 2008 8:27 am Post subject: 2 strokes

ONLY 20 YEARS? HAHAHAHAHA WHAT MOTOR WHAT OIL?

  

 

  MARK

  

  

 

 --

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu Apr 03, 2008 9:23 am Post subject: 2 strokes

At 08:43 AM 4/3/2008, cristalclear13 wrote:

 	  Quote: 	
		  ... I simply wanted to know if there was a better way to measure it than 

using a 2/3 cup measuring cup from my kitchen (and no, I'm not using that 

same cup to make my chocolate chip cookies afterwards)....


	


Sure.  Pour a whole bottle of oil into the can and then add the appropriate 

amount of gas (for me, two 8 oz bottles of oil, 5 gallons of gas, for the 

40:1 mixture my Cuyuna drinks, and still room to shake it in a 6 gallon can).



-Dana



--

  Suicidal twin kills sister by mistake!

Don G

Joined: 10 Jan 2006
Posts: 156
Location: Central Illinois

Posted: Thu Apr 03, 2008 1:11 pm Post subject: Re: 2 strokes

Mr. knowvne,,

IN regards to your question:



"Guys Is a little too much ok??? That  has got to be better than not quite enough...."



Many Years ago, I worked for a large chainsaw manufacturer, and we had not long before changed our recommended mix ratio from 40:1 to 50:1.

During the first year we began to experience a large number of warranty failures related to piston/cylinder seizure. Upon investigations we discovered most all of the dealers were still recommending the old ratio of 40:1....we had a heck of a time getting them to change.  To these old timers they just couldn't understand why a little more wouldn't be better.

So....at our dealer service schools, we rigged up a saw with a simple thermocouple under the spark plug to read CHT and Found an instrument with a large face  so it could be easly read. Then we would take along 3 cans of fuel with us. 1 can at 50:1 mix  and another at 40:1 and another at 25:1.

 With the saw and carb properly adjusted on the recommended 50:1 ratio fuel mix (remember adjustable jet carbs?) we would run the saw at full RPMS and let the CHT stabilize...then shut it off, dump the fuel and fill it from the next can...at 40: 1 and repeat...this run showed a higher CHT...then we would repeat and do it again with the 25:1..which showed even higher CHT. I can remember some of those old timers accusing us of trying to trick them...but after this demonstration most of them finally got it.

Generally we would then spend a half a day trying to explain the reasons this happens, which I wont go into here, but rest assured...MORE oil in the mix is NOT better. 

If you want to split hairs, Since all manufacturers calculate a safety margin for recommended mix...a little less is actually safer then a little more...but stick with recommendations from the manufacturer. 



We engineers that work for engine companies dont calculate these ratios haphazardly believe me, because for us, its a matter of dollars spent on warranty claims...and the reputation of our products.

_________________
Don G.
Central Illinois
Kitfox IV Speedster
Luscombe 8A
RV9A

knowvne(at)aol.com
Guest

Posted: Thu Apr 03, 2008 2:42 pm Post subject: 2 strokes

Hi Don Question for you..

  Is it even possible to build a two stroke motor so the piston and Cylinder expand and contract at the same rate? Also what's your take on Hirth and what they do VS Rotax...Â 

  

 

  

 

  

 

  Mark

 

 

 --

Don G

Joined: 10 Jan 2006
Posts: 156
Location: Central Illinois

Posted: Thu Apr 03, 2008 3:41 pm Post subject: Re: 2 strokes

Mark, when we started using Nickasel coatings instead of steel sleeves and "cam ground" pistons...we pretty much got the expansion "rates" close. The big problem with the piston expansion is its construction...and needing to be heavier(thicker) in the wrist pin area, so that gives some design problems when considering expansion...thus the "cam ground " design (slightly oval when cold).

 The need for as little weight in the piston as possible vs making the piston heavy enough to absorb the heat. you just have to decide on a compromise. Also, what many people dont realize is a small aircooled 2 cycle gasoline engine is about 30% aircooled and 70% "fuel cooled". Meaning the incoming charge of fuel air mix is responsible for removeing about 70%of the heat from the engine...and about 90% from the piston. This feature is in essence why the 2 cycle design can be so much lighter than a 4 stroke. A 4 stroke simply needs more mass to allow the slower transfer of heat thru the cooling system, due to the fact it does not benefit from the "fuel charge cooling" but by a small percent in comparison..



Due to the higher cooling effect of gasoline vs oil...you have better removal of heat with a leaner oil mix in any given 2 cycle...one of the reasons you dont want to mix the oil heavy. 

But this is not the only reason...the fact that carbs are "vacuum operated fuel injectors",,,, the higher the viscosity of the fuel mix, the less fuel flows thru the main jet and a given manifold vacuum....resulting in a leaner charge altogether unless the carb is jetted to compensate, which would be a custom modification.



I really have no comment on Hirth vs Rotax that should be posted publically, because I have no personal experience with Hirth engines ayt all.

_________________
Don G.
Central Illinois
Kitfox IV Speedster
Luscombe 8A
RV9A

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Thu Apr 03, 2008 5:34 pm Post subject: 2 strokes

At 05:11 PM 4/3/2008, Don G wrote:



 	  Quote: 	
		    ...With the saw and carb properly adjusted on the recommended 50:1 ratio 

 fuel mix (remember adjustable jet carbs?) we would run the saw at full 

 RPMS and let the CHT stabilize...then shut it off, dump the fuel and fill 

 it from the next can...at 40: 1 and repeat...this run showed a higher 

 CHT...then we would repeat and do it again with the 25:1..which showed 

 even higher CHT....


	


I'm not surprised at all.  If the carb was adjusted for 50:1, running 40:1 

or 25:1 means less fuel, i.e. a LEAN fuel/air mixture, which we all know is 

a bad thing.  If you change your oil ratio in either direction you have to 

adjust the jetting to compensate.



However back to the original question, it's not super critical, you don't 

have to measure it precisely to the last drop... but it should be close to 

what the engine manufacturer recommends.



-Dana



--

  War doesn't determine who's right but who's left.

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