skiman762

The amount of smoke coming from the muffler tells you nothing about whether you have the correct fuel.mixtures. Usually there will be a puff of smoke when the throttle is advanced rapidly.

jlkonn

My Feedback: (1)

Ford?
[sm=bananahead.gif]

pe reivers

either Ford, or BMW
these guys show smoke whenever they throttle up!

Hobbsy

My Feedback: (102)

Chevy, Dodge and any Japanese car or truck.

skiman762

I really hate break your Saito loving hearts but that is straight from SAITO

suprise suprise suprise

Hobbsy

My Feedback: (102)

Ski, those words have been spoken by many here including the late Mr. Robison, for the simple reason that the smoke does not tell you anything.

skiman762

I know but I was amazed at how many people think ''good smoke'' means things are ok .

liquid_TR

Sound is everything for an engine IMO.

you can hear it knock, bog down, lean-out, rich-out, flactuate rpm, idle, bearing noise, etc... If your ear is trained for the particular engines you have in hand, I bet you will never have mechanical problems with them.

Hobbsy

My Feedback: (102)

You got that right.

w8ye

My Feedback: (16)

Nothing makes more smoke than a Y-S at acceleration when it is set correctly

skiman762

True they smoke pretty good all the time for that matter
Good to fly late in the day when the bugs come out

fiery

My Feedback: (2)

My MVVS .49 really smokes (like it has a smoke pump) on 80% methanol 20% castor fuel.

I think the castor I am using (I inherited it from a modeller who gave the hobby away) is not of the greatest quality.

The MVVS shows no ill effects however, and I really like the smoke trail. Throttling is not quite as good as when I use 10% synth (klotz) and 10% quality castor as lube (my usual lube package for 2 strokes).

I am nicknaming the engine "the goo factory" for what it does to the airframe ....

buzzingb

My Feedback: (2)

Some fuels are easier to read in the vapor trail out the exhaust. I once used Wildacat and I could tell if the engine was rich enough most of the time by vapor trail but now I am using Magnum and can't tell anything from the vapor trail or oil in air. I don't know what the difference is but there is a difference and now I don't pay the vapor trail a lot of attention. I use to fly when the sky was blue and look for a slight oil vapor exhaust trail with a puff of smoke in a hard turn. When I saw this I knew the mixture was close but now I can't say this with Magnum.

Flyboy Dave

My Feedback: (21)

I disagree. If you know your engine and your fuel....you can tell exactly how the mixture is
according to the smoke trail. If you can't tell how your engine is running by looking at the smoke
trail....keep working at it. The puffs of smoke at different settings/openings are only temporary
indicators of the setting you just left.

It is true that a build up of castor in a muffler can smoke for a while, and give a false indicator.

FBD.

MR G

I don't believe you tell where the needle setting is but I do believe that you can tell an engine is running rich or lean by the smoke trail.

I always like a smoke trail coming from my airplanes.

MR G

proptop

My Feedback: (8)

I kinda like to use the smoke trail as an additional indicator...
After setting the mixture by ear and all the other senses
You adjust by sound, smell, sight, and general feel...

The smoke trail, or absence of same, can help. If there are several airplanes flying at the same time, and it's hard to distinguish just exactly what your engine is doing (by sound ). Most of my 2 strokes don't put out much smoke though, so it's not the best indicator...but like I said, it can help.

I have seen some guys flying their (seems like especially ) Saito engines rich enough to fog half the field...that's a bit much, but if ya don't see a good smoke trail from your 4 stroker, then I'd say it's too lean.

Fuel selection can make a substantial difference as to the amount of smoke as well ... I have noticed that occasionally.

Flyboy Dave

My Feedback: (21)

I can't really believe that some people think that the mixture setting cannot be
seen and determined by the smoke trail of the engine.....good grief. [X(]

[sm=stupid.gif]

rcdude7

My Feedback: (264)

That's what I've always thought too. YS engines don't need a smoke system, It comes standard, no extra charge.

gkamysz

My Feedback: (19)

You know the engine is running rich. YS run rich all the time to deal with the high compression ratio due to the boost. Running rich prevents detonation. So chances are the higher performance the engine is and the richer it needs to be run the more smoke you'll have. But it will also depend on the type and amount of oil.

But I agree, with a particular fuel and engine you could acclimate yourself to know whether or not the needle is close. But there is no way to compare different engines or different fuels.

skiman762

I run my magnum 4 stroke 300 rpm rich from the first click it goes peak with a tach and no smoke trail well if you catch it just right you can see some smoke but no tell tale trail
I have tried 400-500 rich no smoke trial but it runs too rich
I guess some fuels and engines leave more smoke then others maybe in a cowl the temps get higher mine is out in the air and is never hot or even real warm to the touch except the exhuast pipe.
I just tore one down and it is as clean and polished as you could ask for after 2 year all it needed was to wipe the chamber and it was clean too I guess castor does the trick
I know as soon as I switched form cruelpower to omega it ran better too your results may vary

w8ye

My Feedback: (16)

I have a OS 91 Surpass II that will not leave a trail unless it is so rich it'll hardly run

Bax

My Feedback: (11)

As has been said, if you KNOW your engine and fuel, then you can use the smoke trail to determine how it's performing. However, it must be repeated that you must be consistent in using one type of fuel and be consistent in how you set the engine. That being said, one cannot state, though, that smoke is an absolute indicator. The amount of smoke emitted by an engine is determined by the mixture setting, the type of oil in the fuel, and the percentage of oil in the mix, as well as how long the exhaust residue lingers in the muffler to get "cooked". These things will all pretty much be specific to an engine installation. If your buddy uses a different engine, prop, and fuel, you can't tell how rich or lean his engine happens to be if you compare its smoke trail to the smoke trail your engine leaves.

Bottom line? GET TO KNOW YOUR ENGINE!

Waco Driver

Has anyone else noticed that inverted 4 strokes smoke considerably more, and that the breather oil discharge is significantly less, than when mounted cylinder head up.

I do not judge mixture strength by the vapor trail as the sky background hides much of the vapor trail when overcast. Also fuels with no castor generate very little smoke.

blw

My Feedback: (3)

Bax has it right.

A smoking Saito is a sign it is too rich. A well tuned one gives off some, but much less than others. There is a guy at the field who is familiar mostly with OS 4 strokes and he always insists that I'm too lean, which I'm not.

Some people don't go by smoke at all and that's okay if they know their engines by other means such as throttle checks, sound, etc. To each their own. Going by smoke probably leaves room for a lot of error if that's all you know.

Cyclic Hardover

My Feedback: (3)

Along with what Bax said on getting to know your engine, Judging from the glow engine section for many years, most have no clue. The odds of a decent brand name glow engine running like crap is very slim and comes down to the owner not knowing what he's doing.