Gas engine tuning for newbies....

[k8svrick]

FYI - I found the same info on a single post on the author's website at the Greater Southwest Aeromodelers site at http://tech.flygsw.org/walbro_tuneup.htm

[mfuess]

Thanks Rick,


Mark Fuess
Greater Southwest Aero Modelers

[storklappe]

Mfuess,

With a DA-100, is the "burble" that you hear at about 1/3 throttle actually 4-stroking? The DA guys say that the mid-range burble is normal.

[BorderLine]

Well I tuned my DA 100 engine to the Xipp method. Opened the high end by almost 1/2 turn ,closed Bottom end about 3/4 turn. Engine seemed to have much better transition. 5 minutes into my flight I lost power from 1/2 throttle to full throttle. Went to land plane as I came in over runway engine died,Plane came down hard on Gear ,ripping it off and putting 3 holes through the wings. Oh well, I've repaired Plane.
It sounds to me as if engine leaned out, with elevation change. We fly at 16' above sea level in Surrey.
What do you guys reccomend...Opening the low end???

BorderLine..

[krayzc]

how was the transistion on the ground after your tuning? I do not move the needles so much in one shot. I tune a scrrew driver blade and then re-start the motor and check it out. Once my high is set and then i start messing with the low i usually end up having to richen the high from my leaning of the low. I take care of the high 1st......

and yes something is lean with those dead sticks

[BorderLine]

Transition seemed to be very good. It took me 1/2 hour to complete the tuning. I did only adjust in small increments and then restarted. I should of maybe run the engine at full throttle for another minute at the end, to see if it would lean out.

BorderLine

[lennyk]

Mark,

Tuned my ZDZ as per your guide a few weeks ago and so far it is running great, practically no burble which used to irritate me.
Its a little harder to start now, before it was about 6 flips choke/full, 6 (no choke,full), 1 flip start
now its like 10-10-1 or so, still fine tuning how many flips but I can live with that once I have a good idea of the starting procedure before it floods.

thanks again

[Billa]

Mark,

Is it possible to get your opinion on post # 176 about the DA 50 flooding ? If this is already covered in the string then kindly point me thataway - I might have missed it.
Thanks,
Aamer

[Malves]

Hey guys,

Not sure if this has been posted and if it is of any help, but I thought I'd share...maybe it is of any help.

[rcmergler]

just got a know mtw can for my da-50, and it seems harder to tune... any pointers

[mfuess]

	Quote: Originally Posted by rcmergler
	just got a new mtw can for my da-50, and it seems harder to tune... any pointers

Some engines are a little more difficult to tune with canister mufflers. However, it still tunes up the same.

[rcmergler]

pk so new problem with the da50.. i had it running perfect on the ground and then it just started running like crap and then died. at first i thought it was the fuel, but i refueled it and now it wont even start, it fired for a couple times and now nothing. i think it mght be a spark plug but not to sure... any help

[alec taylor]

if moter tuned to fly at 400 ft. asl then you fly at sea level , do you have to alter the high end needle. if so which way. 3w170 ? alex

[Tired Old Man]

A 400' change in elevation will not have an appreciable affect on carb tuning. If so we would forever be chasing the needle tuning for the constant altitude changes our planes fly through. The diaphragm carbs we use are generally self compensating for altitude changes of well over 2,000'. If you have the carb well tuned for your local field altitude there's really no need to fuss with it when flying at a field that's 1,500' either way of the home field. Any gains will be negligible.

There have been planes that have flown with starting density altitudes of below sea level and ended up flying above 18,000' asl without any carb adjustments. Many others frequently fly at altitudes over 12,000' that have carbs originally tuned for a base altitude of 500' or less. However, they do start out in an excellent state of tune. No further adjustments are ever made.

The trick is being accurate with the original needle settings.

[alec taylor]

thanks for that