I've flown glow for some time and am very good at tuning engines. I recently acquired a 50cc gas engine, and it runs great. The engine is mounted inverted, so the mixture knobs are underneath the engine. It looks like I will have to adjust the mixture with the engine off because of this and the close proximity to the nearly two foot long prop! That could take quite some time, so I am wondering exactly how you adjust the high end. Do you just turn it a little, start it up, and tach it. Then shut it off, move a bit more, start it up, and tach it, etc? That seems like it will take a long time and put undue stress on the engine.

As you mentioned above is how I couse tune my engine. Then I fly the airplane, see how the engine sounds and determine if I need to lean or richen it by how it sounds and performs in level flight, inverted and uplines. Land fine adjust, take-off and do it all again until it sounds perfect.

I don't worry about getting perfect settings until I fly it. Just want it to be running good. This doesn't take as long as it sounds.

yes with the high adjust for peak and then maybe open the high a screw driver blade only for that small amount of richness. move each needle a screwdriver blade at a time as a little goes a long way on a gas motor. Adjust the low end for as close to clean mid range as possible, the low end will still have a slight burble to it. After all is set pull the plug right after flying to see if you are running the pretty tan color and not gray or dray black. of which would incicate lean or rich.

Trying to set the high needle with the engine running has been known to place quite a bit of stress on the operator[X(] Run, then shut down, turn the needle in small increments, then start again to check.

I always want to make an extension tool so that I can adjust the high or low needle while the engine is idle, probably from outside the cowl. Use a screw drive is quite hard for the purpose because of engine vibration.

Anybody knows such a tool in existence?

so easy to shut it down and make adjustment as body parts take a while to heal and some part do not grow back once lost....things that make u go hum....

B&B Specialties, has a carb tuning tool that works like a charm to adjust the mixtures on gas engines. In my opinion adjusting the engine with it running is the ONLY way to adust an engine.

BTW Maybe you can call me lucky, but I have never been bitten, that tool is the charm.

Someday you'll be able to go by the nick name "Stubby"

Pat - I'm surprised that you nor anyone else hasn't suggested "start by setting the needles per the manufacturers' manual." Those are usually pretty close, and shorten somewhat the start/run/shutoff/adjust cycle.

However - as you, and others, have noted.... it AIN'T a "good thing" to adjust gassers while running, ever. IMO, of course.

Oh yes, I have it set as recommended and it is very close and running like a dream. I just need to make sure it's not a little lean or anything. I'll definitely be adjusting engine off.
Thanks for letting me know about the needle sensitivity. That sure is different than glow.


P.S. I hope I don't get the nickname stubby I give piano concerts locally when time allows! [:@]

Quite literally, many of the current Walbro's on 50cc size engines are very sensitive. The closer you get to the optimal setup, the more critical the degree of "turn" on the screw. Also remember low affects high, but not the opposite.
Usually, the final adjustments on mine seem to be the thickness of the screwdriver blade + or - , so it is nowhere near "1/8th turn", but actually quite less.

Bob,

I pretty much hope and presume that most people would read the instructions (if it had any) and start with both needles somewhere between 1-1/2 ans 2 turns open. Those that bought engines without instructions, and there are a few that come that way, have an honest reason not to know.

A fair number of engines have the carb located where the needles point forward towards the propeller, generally leaving only an inch or two of free space between the back of the propeller and the carb. Tuning one of those with it running is akin to trying to remove some bound up string between the back of a lawn mower blade and the cover with the mower running. Not real smart.

Other engines have the carb rotated where the needles point to the side or rear of the engine. The ones to the rear are just fine to tune engine running with the ones pointing to the side requiring care and attention to avoid moving a body part or two into the prop arc. When that happens the results are the same. Either the tool, the body part, or both are separated from the owner.

Tuning the engine running is the only way an engine can be tuned and know it's right. To each his own! I know I'm getting the most out of my engine, without the worry of wether it's to lean, to rich is easy to tell, too lean, which can be more damaging is not, not until the engine dies, by that time it's to late.

But by all means don't let me convince you to do it my way, if your happy doing it one flight at a time, so am I. How many times have you read threads on RC Universe, trying to get an engine to run right? Half the threads are about how to tune an engine, my way is perfect.

BTW I have never in 25 years running gas, have I ever been nicked by the prop! Lucky? Maybe, but I don't think so, just careful.

Dale

GreaTOne 65,

I tune with them running as well but there's no way I can in good conscience advise others to do so. I've hand propped full scale planes but I won't advise others to do so. My point is that because you and I get away with it does not mean others will, and should an accident happen we are part of the liability chain if we advised to tune with the engine running. Therefore I do not and will not ever recommend or suggest that an engine be tuned with the engine running. The ONLY safe way is with the engine shut down.

More work, more time, absolutely, but you cannot get hurt that way. If you're in the U.S. you will not escape the liability apportionment in a civil injury trial had you given advice promoting the tuning of a running engine. Just because you said it over the internet does not relieve you of civil liabilty and believe that you will be found regardless of you internet name. In over 25 years I'm surprised that you have never learned how responsibility, liability and litigation works.

No, I'm not a trial attorney or para legal but I've been closely associated with legal professionals (civil and criminal trial attorneys, DA's, Sheriffs, and cops) and I've payed a little attention along the way. Because you are not aware of your liability is not an excuse when the judge's gavel hits the table. There's too much to lose if somebody is stupid and places a part of their body or other object into the path of a powered propeller. This is why I say what I do and will never advise tuning a running propeller driven engine.

Think on this for awhile and consider what you might want to do.

But by all means don't let me convince you to do it my way, if your happy doing it one flight at a time, so am I.

Pat, I know what you say is true, but didn't I absolve myself by the above statement? I am not a dealer, nor am I affiliated with any company, I'm just an average Joe Blow. I am well aware of the "sue unto you" mentality, but as far as I'm concerned if you aren't coordinated enough, or careful enough to tune an engine with it running, your in the wrong hobby. I don't know anyone who flies glo engines that don't tune them running? Do you?

Now you know, Pat, I am not trying to argue with you, I have great respect for you, you have a lot to offer that I agree with.

Except propellers! LOL!!

Dale

I've tried to tune with the engine running, but my shaking fingers never matched the harmonics of the engine shaking to get the screw driver in the slot long enought to turn the needle. Now if I was to down a beer or ten I might vibrate more closely to the engines shake and manage to get er done. Course I would only want to try it that way if I was at the field alone cause I'd not want anyone to know what a complete idiot I was[&:]

Well, I always tune glow engines running, but IMHO they're a completely different animal considering the needles are pitched away from the prop, have larger knobs, aren't as sensitive, and are smaller (easier to wrap hand around). I'll stick to adjusting when off. I wasn't sure how you guys do it, but apparently most of you do it the same way I was proposing.

Thanks again!

GreaTOne,

Unfortunately our legal system has changed and now sees things much differently that it used to. A long time ago each person was generally saccountable for their own actions but times changed and a large number of people seem to think that everyone else is responsible, but not themselves. Perhaps it's part of an entitlement mentality and a need for many to have someone else take care of them rather than take care of themselves. A somewhat similar attitude has ben adopted in many legal corners and until that turns around anything that can be construed as "permission" or encouragement can bite your butt big time. One of the reasons I don't say much of anything in some areas.

As for props, no big deal. Everyone eventually finds the one or ones that work best for their engine, airframe, and flight parameters situation so it would be darned hard to come up with a one size fits for everyone prop. What makes that even more difficult is that, especially with wood props, few of the same size and type work the same. Probably the closest to consistent is APC but they are not a good candidate for large gassers.

Nathan,

One thing is certain. You did not have a "stupid" question. It was quite good and well worth bringing around periodically.

Nice thing about glow engines. Though tuning any type of engine with your hands or face near a spinning propeller is dangerous, but at least with a glow engine you're behind the meat cleaver. Gassers typically only provide an inch or so between the back of the spinning prop and the business end of the needles to work within. Rear induction engines are a different animal and easy to work with as long as you stay behind the prop and keep everything well secured. Even then I like to have someone else close by when I'm working with a running engine.

Never, ever, lean over a prop to do any kind of work!!! I get nervous everytime I see someone reach around a prop to remove a glow driver.

Just for my own knowledge. If somebody writes his own experience on intenet and another person tries to repeat and gets hurt, can the 2nd sue the 1st?

The argument is that there are so many advice posts on RCU and if a newbie is not careful enough, he can get injuried, regardless of whether he is following the advice or not.

The bottomline is that this is not a quite safe hobby.

http://bennettbuilt.com/page10.htm

Nathan, Pat, and the others who have been responding to this thread, maybe I should have added that I would not attempt to adjust an engine without one of these. It really takes the worry out of being close! I would rather tune a gas engine than a glo engine, but I only had Fox's, enyas, and OS. the ones less than an inch from your knuckles. One other thing I can truthfully say, I have never cooked an engine from the carb being to lean.

In all situations except racing the start turn and start method is good enough.
For perfectionist, like me, it has to be running and it has to be retuned when ever the weather changes.

It always seems to be just a little different every time I tune it.
Yet my String Trimmer and riding lawn mower never get the Carb. retuned.

First I tune the low needle since it has more of an effect on the high end mixture than the reverse situation. Once the low needle is perfect I do a check on the high end. It it drops RPM's at WOT after a few seconds it's to lean. Richen it a little at a time until it holds a constant WOT RPM for at least 5 seconds. If the WOT RPM's rise slowly it's too rich. Lean it a little at a time. A lot of times after you tune the low end the high kind of rides with it and really doesn't need much adjusting if at all. Always check to be sure though.

Adjusting with the engine running gives you better and faster feedback but has its risks. I've done both, it depends where the needles are. For a rear induction it's possible. For a side induction with the needles pointing forward, forget about it.

Good tool, but only useful with cowling off. How do you make adjustments cowling on?

Saying you have to tune it running is just plain silly. In the air with differing cowl pressures and having the engine unloading in flight your fine tuned sitting on the ground engine isn't tuned for actual flying conditions. Any engine with more thrust than weight will never stop flying to match the setting you gave it on the ground. Also most of your flying will be at a throttle setting thats far less than what power is needed to hover. Only flying it will tell you if it will sag in an up line or if you have too much 4 cycling straight and level.
And ONLY flying it will tell you how hot it becomes if you run full throttle and for how long you can run full throttle before you cook something.

Guy,

Checked with Bowman today. The rings we might want to try will run about $10.00 each. I'll be ordering a bunch of them for another project and let you know how they work out.