not too long ago I read a article here in one of the forums that was very detailed about fine tuning our 50 cc engines. I cannot find it again, sure would like a copy. Does anyone remember where it was?

thanks

Easy guide is just to tune the hi end first for max RPM's, and then work the low end to get a decent idle and good transition. A lot nicer (although dangerous and much more difficult) to make the adjustments when the engine is running. If its a rear carb. engine it should not be too hard to make the adjustments.

thanks Sarge for the reply. The page I was referring to is a full page document with very detailed steps in fine tuning bigger Engines. Would be very helpfull for newcommers to Giant Aircraft . I wanted to use it in our Club as training Aid.

I believe that Dick Hanson would know.

Here are the basic steps when the engine is warm.

#1 set High for peak and back off a couple of hundred rpm.
#2 set Low for good idle and transition.
#3 Re-set High as in #1.
Low affects High so every time you change the low re-set the High. That is it, not really much to it. I have used these simple steps now for many years.
Ralph

Checkout BME's website. They have a several page long instruction manual that can be used on any gas engine. They also have a full chart for mixing gas/oil. Its very helpful.

Was this the post you were refering too?

Carbs aren't too difficult to tune up if you know what you're doing. First of all, you need to know how the carb works and how the settings interact with each other. About 95% of all the gas airplanes I've seen at the field are somewhat out of tune. How can I tell this? Simple, at some point the engines "four cycle" in flight. Two Cycle engines are not supposed to "four cycle" PERIOD. This is caused by a rich mixture that is forcing the sparkplug to intermittantly miss making it sound like a four stroke. This is not good. HOWEVER the good news is; gasoline two stroke engines are very very tollerant of rich settings (most of the time) and will run fine. You'll just consume a little more gasoline than necessary, and create a little more oil mess on your plane. You may eventually foul your spark plug as well. So why do so many people leave their engines tuned like this? Simple answer, the engine will start much easier when it's cold AND there's little or no warm up time needed prior to flying. Those are pretty good reasons! But the fact is... the engine is not running like it's supposed to.

(1) The lowend needle on a Walbro carb is ALWAYS the one closest to the engine, the highend needle is the closest one to the intake/choke.

(2) There is no fuel adjustment for idle fuel, only air feed set by the idle stop or servo.

(3) Both lowend AND highend needles feed the topend fuel supply.

Let's tune up a Walbro!

Set the lowend & highend needles to about 1 to 1 1/2 turns each. Choke the carb or prime it, until the carb is wet. Fire up the engine and let it warm up. Let's set the topend first since it's the easier of the two. Go to full throttle. Adjust the topend needle for peak RPM. Leave it wide open for about a minute to see if it changes any. Should the engine go lean, open the lowend needle slightly, if this dosen't work... you will have to adjust the needle valve inside the carb.( I will explain this later) If the topend runs OK, then slowly pull the throttle down until the engine begins to "four cycle" hold the throttle there. Adjust the lowend needle until the "four cycling" stops. Now lower the throttle more until it "four cycles" again, and adjust the lowend again. Keep doing this until you reach full idle. Now, from full idle begin to throttle up until the engine starts to bog or hesitate. Open up the topend needle just enough to eliminate the bog or hesitation.

When this is done right, you will be able to set the throttle in any position and it won't four cycle, plus you will be able to transition from idle to full power without any hesitation at all.

Hope that helps.....

[link=http://www.flyingcirkus.com/forum/Gas_Engine_Tuning_for_newbies%25/m_51010/tm.htm]Taken from this thread...click me[/link]

thanks, mstroh3961, you've hit the nail on the head.
Buchtes

I would follow XIPP post to the letter. once I followed his thread and fine tuned my engine I was consitently gettin more power and longer flights every time out without overheating the engine. Turning over 7100 rpms on a ZDZ 50NG on 32:1 mobil mx2t and a menz 22x8 prop.