Gas engine tuning for newbies....

[mfuess]

	Quote: Originally Posted by flynz4me
	Symptoms of a diaphragm carb having a float valve leak: (1) Rough idle, and engine loading up. (2) Fuel dripping from the carb when its not running (3) Lowend needle does not tune well. SOLUTION: Replace the float valve and adjust the lever to its flush position OR use a "W" gauge to set it. Mark - What is the "Float valve??" Is it the needle valve?

Yes.

[flynz4me]

OK thanks... Where do I order a rebuild kit for my HDA 48??

[RTK]

Go to your local mower/saw shop and pic one up there.

[rcflyer]

	Quote: Originally Posted by mfuess
	Before you begin your tuneup, reset your needles to factory settings to start from gouund zero. It's best to set the topend first. Start your engine, let it warm up. Transition to full throttle. Adjust the HIGHEND NEEDLE to peak RPM. Then, SLOWLY throttle back until the engine begins to FOUR STROKE. At the point, adjust the LOWEND needle until the FOUR STROKING stops. Pull the throttle down more until it FOUR STROKES again and repeat this until you reach full IDLE. NOW, transition up rapidly. IF it sags or bogs, open the LOWEND needle SLIGHTLY until the sagging is gone... YOU"RE DONE! One big MISTAKE people make (when they tune up a gasser) is to peak the engine then back off the needle to richen it up slightly just like a glow fuel engine. DO NOT DO THAT! Once your carb is properly tuned to peak it will maintain the CORRECT air to fuel balance. Richening it up only causes the engine to run wet and inefficient. IF you are not sure if you have a good tune, look inside your muffler or pull your spark plug. It'll tell you real quick. If it's black & wet its time to re-do your tune.

I would like to request that someone makes a youtube video on mfuess tuning method. I am still not sure what "four stroking" sounds like and a video will definitely be helpful. Thanks

[krayzc]

a well tune gas engine with a throttle curve sure is very nice to run with make the low very rich and u will quickly know what 4 stroking sounds like is how i learned.

[Al Lewis]

Make it sound like this and you'll be very close.

http://media.putfile.com/DL-50-Tunin...-Vess-23A-Prop

[mogley]

what should a properly tuned da50 turn with a 22x8 menz on a slim line mufffler?

same question with a Mejlik 23x8

all at sealevel?

thanks

[rcign]

Asking wwwhat a DA50 will turn is like asking what oil is best Now......A little problem with semantics....
First off, gasser carbs don't have a float valve or even a float, it wouldn't work unless the carb was never rotated from moslty level, where it can float on the fuel..In a float bowl..
The float connects to a lever that lifts the inlet needle off the seat to admit more fuel to the carb when the fuel level in the float bowl lowers ...A gasser carb has the same inlet needle and lever but it's controlled by a diaphragm with a metal center, opened by atmospheric pressure coming through the hole in the steel carb top...
A "needle" valve is in a glow carb, a tapered needle that admits fuel drawn into the carb from the tank by suction when the piston goes up...Some have a low needle and a high needle, some have a high speed needle and a screw with a flat end...This is an air bleed carb, screwing the flat ended needle in RICHENS the low speed...Screwing it out LEANS the low speed by admitting more air, less fuel...
There is no needle valve as such in a gasser carb...There are 2 needles, a high speed and a low speed..
The low speed needle progressively admits fuel at low speed through 3 little holes in the venturi up to the point where the high speed needle adds to the fuel flow....
And the low speed needle DOES control fuel flow, contrary to what is posted in a forum elsewhere...

[nesikachad]

This is the greatest thread I've read yet on this site.

PROPS to you!!

[JoeAirPort]

	Quote: Originally Posted by mogley
	what should a properly tuned da50 turn with a 22x8 menz on a slim line mufffler? same question with a Mejlik 23x8 all at sealevel? thanks

I can only tell you about my DA-50 on my Menz 22x8. 7000-7200 RPM depending on which carb I had on it. I bought a replacement carb from DA to try and fix a dead stick issue. The new carb dropped my peak RPM by 200-300 RPM. No idea why, no matter what I did to the high speed tuning it would not exceed 7000 RPM. I returned the carb to DA for credit and sold the engine with the old carb on it. When DA tested it on a plane with the old carb they said it had more power than their engine that was on the plane before mine.

[rcmergler]

just one quick question for the experts, went i start my cold da it will not advance without dieing until its at operating temp, once there its killer! so does that mean my low end needs to richen just a bit?

[Al Lewis]

It means let your engine warm up.

[3ddd]

it means do not lean it out any more,if it were mine i would go rich just about a 1/16th of a turn.on all mine i like to hear just a hint of burbble at about 1/4 to 1/2 throttle

[mtnflyer14]

This thread has really helped me understand the Walbro carb, tuning, etc--thanks to all those with expertise! And, I have a question: I have an older G-38 with electronic ignition, but it has the old WTA-6A carburetor. I would like to replace it with a new carb to improve performance since I fly in Colorado Springs at greater than 6,000 feet altitude. Does anyone know if the Walbro WT-540 would be a good replacement choice? Thanks in advance.

[RV4JMMD]

Ok, heres my problem.
Setup:
75cc Aeroworks 260, ZDZ Super 80, Walbro WJ-71, Klotz 40:1, Elevation is >6000'
Menz 26X8
Top rpm is 6450
Transition is smooth but idles at 2000, it might be a little rich too. When ran at full throttle and then chopped it goes SO low it almost dies and slowly pops back up to 2000. If I lean it out enough it will not die when the throttle is chopped but then the mid range is a little rich. I tried to set up a throttle-needle mix with a servo on the low needle but that didn't seem to make a bit of differenc in performance nor could I get the idle below 18 or 1900. I havent tried a bell mouth stack. ?????????????????????????????????????????????????? ???????
The best that I can get it seems to still be a little rich midrange. I might just have to live with that. Everyones gassers up here are run RICH and I know thats not how they are supposed to run, does anyone have a video of what they should sound like??? preferably in the midrange. My top end is awesome, sounds like a Mooney but the middle is popping more than I like to hear but I would like to compare it to someone elses midrange.
Thanks.