Re: 2 strokes are prone to seizing


britmcman99
 

I propose we rename this list "Q-Strokes". I think I'm having one now. Please subscribe to Q-Performance or to any of the many other alternative engine lists available. Live long, fly four stroke.

Phil Lankford


On Mar 24, 2012, at 6:21 PM, "alertboryelis" <ajolliffe50@...> wrote:

NO GAS going into the cylender meens no OIL mixing, when the prop is freeweeling dry pistons result ,SEIZURE....

--- In Q-LIST@..., "Allan" <afarr@...> wrote:

Hi. No it doesn't know how fast it's going, but it "knows" how much load is on the propeller. When the prop/engine is unloaded it can cause high egt's and a seizure. The condition is more likely to occur in fast/slippery aircraft than a slow/draggy one. It doesn't have to be "over Revving" to cause the problem, in fact one of the danger areas is around 4000 revs. You obviously don't like to hear this but it is not "just my opinion". Look it up, there are interesting articles about it.
Allan
Btw my 503 is rated for 6800 WOT not 6500.

--- In Q-LIST@..., Armilite@ wrote:


Allan:

So your 2 stroke engine knows how fast(MPH) it's going? Wish mine did, I
wouldn't need a Speedo. If you stay within the acceptable RPMs, recommended
by Rotax, you should be OK. Some people tend to push the envelope. That's
6500rpm MAX for most Rotax 2 stroke engines, I have read. Only the 618UL was
rated for 6800rpm, and those RPMs, are only for takeoff, 1 minute, 30
seconds. Then their throttled back. Most people fly between 4000rpms - 6250rpms
MAX.

Most seizures are caused by what I stated below.
"Seizures are caused by many different situations, Heat (lack of proper
cooling), lack of proper lubrication (Oil Mix), or not using the Proper Type
of Oil, Over Revving the engine with no load, are the main reasons."<

Just my opinion.
Rich Gillen
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1a. Re: 2 strokes are prone to seizing
Posted by: "Allan" afarr@ allan_farr
Date: Wed Mar 21, 2012 2:03 am ((PDT))

Hi. I'm not sure why you mention the "up down right or left" bit, I wasn't
saying anything about engine position. I am saying that 2 strokes are
known to be more subceptable to seizing on a fast/slippery aeroplane -
something to do with unloading the prop. I have read several interesting articles
about it. Here's one - http://curedcomposites.com/twostroke.html
Regards
Allan

--- In Q-LIST@..., Armilite@ wrote:


Allen:

2 Strokes don't know if their going up, or down, right or left. You can
hang them up, or down on a plane. Seizures are caused by many different
situations, Heat (lack of proper cooling), lack of proper lubrication
(Oil Mix),
or not using the Proper Type of Oil, Over Revving the engine with no
load,
are the main reasons. People have seized them just sitting on the
ground to
long, mounted on test engine stands, flying in level flight, rapid
decents, etc. You have seizures on both Air Cooled, and Water Cooled
engines.
There is a difference in 2 stroke oils.

Trouble is, most people don't document what went wrong, type of oil
used,
all the details, etc. Some guys get as little as 200hrs out of and
engine,
and another may get 800-1200+hrs.

The one thing you read about in almost every seizure post, is melted
Aluminium(Piston) on the cylinder walls, not on the top of the piston or
combustion chamber. That's HEAT, & Lack of proper lubrication.

Raw Aluminium melts at something like 1220F, pistons are made of many
different alloys, which probably give them a little higher melting
point. Point
is, people are melting them in there cyclinders. Friction causes HEAT. I
believe there are two types of cylinder sleeves, an alloy of carbon
chrome,
and molybdenum of 200 brinell hardness and something called, I think
nikasil. Which is a coating. I don't know if it's coated on the bare
Aluminium
Cylinder, or on an Iron/steel cylinder liner. Don't know which is
better. Most
engines use an alloy of carbon chrome, and molybdenum.

_http://www.psep.biz/store/ski-doo_cylinder_sleeves.htm_
(http://www.psep.biz/store/ski-doo_cylinder_sleeves.htm)

Just my opinion
Rich Gillen
Ames, IA

===========================================================================
3a. Re: Trying to contact alternate engine owners
Posted by: "Allan" afarr@ allan_farr
Date: Mon Mar 19, 2012 12:56 pm ((PDT))

Hi. I have a Rotax 503 in my Challenger, but from what I understand 2
strokes are prone to seizing if you use them in anything that is
fast/slippery.
Allan




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