Doesnt sound good ... is this worse at idle or WOT?
Can one spray anyhing in the air intake to remove this buildup?


To a certain extent oil baking happens in normal 2 strokes, even
with
the proper approved oils & being diluted with fuel. There are several

sprays or put in the fuel things you can buy that do try to clean the

baked deposits away, some swear by them (the sellers????:-)) others
shrug their shoulders. Even if indeed they do actually work in a
normal
2 stroke, I can't see how they would have any effect in a DFI because

the problem is below in the just air flow crankcase(s).

Fuel additives wont work of course but spraying stuff in the throttle
might ... Still is is maybe something that is better not dont.

Esp. with the optimax it gets in the injectors whatever is in the
cylinders as it uses the comprsssion pressure to pressureize its
airsystem during start up - the reason why fogging the motor will
destroy the injectors.


With the DFIs though there is probably some actual reason to use the

"special" oil because there is a "special" problem they're trying to
mitigate against, without actually admitting it even exists much less

that they're well aware of the design defect in the engines they
sell.

Makes sense .... The silly part is that Merc on their website ALLOWS
the "normal" Premium oil for the optimax. But if asked they strongly
recommend NOT to use it... They dont know what they want...

What I was able to press out of one of their guys is that its ok to use
in an emergency when holding back on the throttle ..

Theu claim it is because it gets recirculated, which I find quiet
the
exaggeration... The only thing it does it flows through the
comprssor
and THEN throough the top crank bearing ... I wonder how this is
recirculation and why home depot oil would have a problem with
that...

Maybe the real reason foit the DFI oil is the temperature
resistance?
Opinions?

They dont want you to use even the best pure syntethic oil ...
wonder
why. Just to make money of their oil?


"Recirculated" is code for it hangs around. i.e. it isn't burnt as
it's
injected not till the engine is at higher revs. It does mean the oil
can
take in more heat, but also lean mixtures even when they don't
detonate
(when these engines are in lean mode they're so lean the mixture
won't
even support detonation), lean mixtures have a very slow flamefront &
so
make all chamber things hotter in general.

Aha .. this definition of recirculation comes closer to the truth

All the time remembering that the piston in these engines is almost
totally uncooled, they claim the air flow through the crankcase(s)
cools
the piston(s) but this is just more knee jerk answer to a very good
question. "If" that answer is correct then the next question is where

does the heat go then?? up ontop of the piston?? so the piston gets
even hotter as this now preheated air is compressed to make it even
hotter?? then the piston really gets even more heat as the charge is
ignited??? no their answer is just more of the same.

Why didnt they spray a little oil at the piston? Might cause oil use
being too high?

I remember the first optimax motors suffered from excessive oil use ..
some people say 1:20 - 1:25 was seen in some motors ... was this oil
cooling?


The answer E-Tec should now give is; Yep we know all about that &
have
decided that if we're to remain EPA compliant with a cheap to build
high
profit 2 stroke, we will just accept there's a real risk of excessive

piston heat buildup when they operate in lean burn mode. However we
have
managed to find a brand new never before known to engine technology
aluminium alloy that we are hoping will be strong enough to survive
the
extreme heat caused when the detonation does occur.

People are praising these things (so far) lets see how it goes ... They
have nice features that hopefully will show up in the 4 strokes, like
no break in no gear ol change due to super duper materials and
tolerances.


Needless to say normal aluminium melts well over 1000F & petrol
will


auto ignite at any temp over 4-500F, so detonation is clearly what

they

know all about & instead of trying to solve the real cause they're

just

"trying" to make the pistons strong enough to survive detonation (&

To be fair: IF the problem is gone then we dont care how ... IF the
motor holds up to the abuse then let it be detonating away as it
pleases

Maybe you can even get it to diesel and power by turning the ignition
off hahaha


related extreme temp rise) long enough that they will have a
reduced
failure rate, such that they can sell a few more till the public

wakes up.

In all fairness I have to say that the DFI motors that are on the
market seem to be holding up well

Where are they?? seriously??? other than the occasional dealer
"demo"
(code=couldn't sell nor give it away) boat there are very few you see
in
regular service. Used to be lots of people with them when the dealers

were all pushing them really hard (& why not turned out in court they

were making a 30% kickback on them!!!) but these days??????

You are right they are declining and on larger and heavier boats there
is little reason to use one. The only advantage I see is the weight
and better powerdevelopment.

Thing is I would get a 4 stroke but for a jetdrive there is just no
option to a 2 stroke. And it a lot of fun

Yes agreed & if you take care of the Opti you should be OK because
it's
a "jet".

My boat is 19' and weighs 1400 lbs with 200 (2 stroke) HP in it you
have to experience the acceleration


The time they can get loaded up while still in lean mode is

What does "loaded up" refer to? = Heat build up in lean mode?

Do I understand that the "lean mode" is just there for the EPA and the
motor could run with no detonation and be fine but not meet EPA?

when they're on a fixed pitch propeller boat with a high top speed ie

lots of propeller pitch. When this type of setup is then used for
long
periods in a say no wake zones the boat is usually ploughing along
nose
high & at lowish revs while still lean, this is when the heat can
really
buildup in the piston (the rest of the chamber stays cool via the
endless supply of seawater). Once the boat clears the no wake zone
the
usr invariably opens it right up to blast away & it's then with the
sudden change from lean mode into make full power & full rich mixture

that the deadly combination occurs, lots of fuel plenty of fire, an
overly hot auto ignition source inside the chamber (really hot
piston) &
very poor fuel atomisation because the injection pressure is just
plain
too low.

Sadly you have the same problem with a jet In harbors and such you
pretty much idel at speeds of 2-5 mph ... This would be bad as well.

However during normal driving you hardly run the jet under 3000 rpm, in
fact it will not plane below 3600 rpm ....

Is it dafe to say that under these conditions (motor is above 3500) you
will never have hot pistons and problems from detonation?

Also when you idle for along period of time and have your motor hot and
lean you will have NO detonation problems when you accelerate slowly to
let the motor cool?

Is there a defined lean mode at a certain rpm range and then all of a
sudden it runs rich? Or is that a gradual process from lean to almost
normal to normal?

In these premises I suggest the E-Tecs will go into detonation
exactly
the same, it's just that they're hoping the new super duper strong
pistons can hang together long enough, till either the usr pulls back
&
settles to cruise or the chamber self cools because there is now lots
of
fuel around because of the normal mixture, it's still a lottery. A
lottery none of the big engine makers will even buy a ticket in....
why????? Well gee they knew what was going to happen with Ficht & I
say
they know about this latest consumer funded experiment also.

Maybe they have a concept of keeping the motor cool with oil, also not
lielly as the ETEC almost runs dry.


Good news for you is that a jet doesn't load the engine the same
way,
the only time the jet can load the engine up is at max power,
anything
below & the load is very much removed from the engine, you'll see
this
in your throttle position 1/2 throttle is lots of revs but not much
power (speed) so cared for you should be confident.

Why would it load at max power? at WOT it should run extra rich. Wont
that keep it nice and cool?

I take it, you dont like Harry?

Na nor he me so it's all pretty fair in that regard:-)

Sorry if it offends you & in deference to you I'll keep today's
Krause
lie to one of his shorter ones, but hey someone has to stand up to
him:-)

Well ... it may offend Harry (not so much me) but please be nice.


Matt