Gas engine tuning for newbies....

[cal_mag]

I can't adjust it while running at full RPM, Even at Idle it is tough. I spent alot of time tweeking it and finally got it right. The method works great.

[excelpoint]

I havnt tryed this yet but if you were to put a bit of fuel tubing over each needle and left it about 10mm longer then you would be able to slip your screw driver into it and it would hold it there even when the engine was crankin. Might give it a go on the weekend. Anyone else got any ideas?

[Neogenesis]

A single flip is all it should take to restart a gasser when it's warm. I wouldn't suggest that anyone get their hands anywhere near a running gasser.....espically when you get to the bigger displacements. Shut it down, make small adjustments....the restart. It's much safer that way. I've got pics of a friends arm after he got hit about 7 times with a 3W 100. It was not a pretty site. Didn't even break the prop, and it was wood. So....be safe.....and don't tune them while they are running.



Neo Out!!!!!

[JoeAirPort]

I assume that the Xipp method is for a broken in engine?

[rcign]

Carbs adjust the same on a new engine as they do on a broken in engine...Only difference between the two is a little more compression from the rings being seated and maybe a little looser crank from the seals wearing in....If the carb is adjusted right in the first place (regardless of "factory" settings) it will need very little changing as the engine is run...

[RappyMan]

Hi All
I have an old G-38 on my modified Roadrunner. It's not a hovering aerobat, but it is a lot of fun & can do quite a bit. The engine is old & my friend put a carb kit in it last summer and used the setting guage to get it just right. It ran really nice, but after a few flights, it got hard to start. You really had to choke it & then it would die after it ran out of the fuel you just choked in it. If I put my hand over the carb intake while it was running & choke it a few times, it would start running fine and run great through the flight. We just had a nice day here, so I got it out and couldn't get any fuel to choke into the carb. I finally squirted some fuel in the intake and did the hand over the intake quickly a few times after it started to get it running. I tweaked on the needle valves to get a smooth slow idle and a good top end. There was just a tiny bit of hesatation on idle to full speed & if the motor sat idleing for quite awhile, it would lag worse. I'm getting 8640 rpms with a APC 18-8 and no cowl around it.
Any ideas on what to try? About a month ago I had it out, choked it & it started on the first flip - gotta get that back somehow!

Thanks
Terry Peterson

[abrous]

My MVVS 45IRS four cycles for a few seconds when I back off the throttle, giving me the impresion that she is going to die. Also the idle target RPM is not always the same.
I must say that my MVVS 45 is brand new with only a few taks of gas through her..
You said that four cycling is perfectly normal for carbs NOT equipped with a "check valve" high speed jet.
How can I distinguish a Walbro carb with or without check valve ?

[petergordon]

	Quote: Originally Posted by excelpoint
	I havnt tryed this yet but if you were to put a bit of fuel tubing over each needle and left it about 10mm longer then you would be able to slip your screw driver into it and it would hold it there even when the engine was crankin. Might give it a go on the weekend. Anyone else got any ideas?

I've done this and it does work. But with the BING carb, the needles are so bloody close together that you can't do it for both needles. So I did it for the high speed as that's the one that needs the guide when the engine is vibrating.

Peter

[Kiwi]

I've heard of guys drilling the cowl and using drinking straws as the guide. I suspect you just push the straw in when the engine is stopped, run it, tune it and then yank the straws afterwards.

Seems like a simple enough method but again guys, if your hand is any place near the prop just dont do it. Stop it, move the needle a 16th of a turn, one flip and test. It may seem slow but its a hang of a lot faster than healing up your smashed up hand.

I personally like rear carbs because you can easily set them up running. Any place else (DA100) no way in heaven am putting my hand in that close.

Kiwi

[rcflyer]

For my glow engines, I tune the low end by pinching the fuel line (close to the carb) and listen for the engine to speed up. I keep tightening the needle valve a little at a time until the engine no longer speeds up when the fuel line is pinched. Then I open the needle back up just a little. Just wondering if this method works on gas engines too?

[RTK]

Nope, takes to long

[JoeAirPort]

To those that have this method down. I need to run my confusion by you and see if you can help me here.

It says to start the high end by adusting to peak RPM. Does that mean adusting the high end until it holds the RPM without sag? Because then he says to open the low end slightly if it does sag. That's my first point of confusion. Seems like both of the needles are trying to achieve the same result (peak RPM without sag). Is this correct? Or am I reading this wrong? How exactly do I adjust my high needle for peak RPM (micro steps please)?

Excuse my thick headedness but I'd like to get the end result he talks about. I tried this once but I didn't get it right. It's a new DA 50 with less than a gallon through it.