Guys, I've got my first gasser, a GP Aeromaster with the Fugi 43cc. The engine is new and I'm using 25:1 mix per instructions. I've run 60 oz of fuel through it and with a 20 X 8 wood prop the best I get is 6150 rpm. Idle is running 1850 and I have resonable transition from low to high and high to low. I'm flying in the Denver area at 5200'. Is this kind of high rpm normal for this altitude? I have not messed with the needle settings from the factory. I flew the plane and it was barely able to fly, I asked GP about this issue and they suggested a 20 X 12 prop but I still think I should be getting another 1000+ rpm's out of this motor. Many thanks, Jerry.

"Factory" settings would be rich at this altitude.
Why does everybody get so hung up on "factory" settings? They are a suggested starting point. You set the needles to whatever it takes to run the very best it can.
Your carb was built in Japan, Singapore or Mexico, the engine in Japan. They got no idea about a CO. summer with adensity altitude of 10,000 ft
Learn to adjust you will have to change from winter to summer setting 2x a year.
I usually go 1 turn rich from the factory setting, that way I know I have to lean it out, then its run twek, run, tweek, Till its right, 1/8 turns on the needles.
After practice you can do it easily....so practice.

Why is it that people will go out and buy that brand new, super 2 or 4 stroke whatever zillion rpm glow engine and darn near twist the needle off trying to find that perfect setting for the most power, usually forgetting that there is also a low needle, but are terrified of changing the position of a carb needle on a gasser?

I have yet to see or hear of a set of gasser instructions that says " Thou Shalt Not Touch The Needles, Use Only The Factory Settings", or even begin to imply that. I'm not getting down on anyone but you read all too often that someone is at the factory settings and they aren't developing close to the rpm levels that they have read of others getting. Therein lies the problem. Factory settings are great for the factory, not your house.

The differences between a glow or gas engine are not all that different enough to matter.

Lean the high end out untill it is maxed out. You can hear the engine pick up RPM and then stumble when it gets too lean. Set it right at max and then back it up the thickness of the slot in the adjustment screw.

Now set the low end like this:

What your going to do is rev it up and then back it down to 1/2 throttle and listen. You'll back it down a click at a time and listen to it. If it misses or gurgles--your too rich and will have to make a small adjustment. This usually involves stopping the motor. No big deal. Stop it. Lean the low end about the thickness of a screwdriver blade. Start it up and run it up to full again. Back it down to 1/2 and hold. Now backit down 1 click at a time. When does it gurgle and miss? 3 clicks down from 1/2? 6 clicks down? Just pay attention and take note of when it starts to act funny.

Each time you start it and run it up to full throttle you will hold it for about 10 seconds. Then back it down to 1/2 throttle and hold for 10 seconds. Back it down 1 click at a time. Hold it for 10 seconds each click.

You should be able to back it down farther and farther each time you make an adjustment.

Make an adjustment. Start it up. Full throttle. Back it down to 1/2 throttle and start counting clicks as you throttle down. Hold each click for 10 seconds. As you lean it and make adjustments--you should be able to back it down farther and farther each time before it gurgles and misses.

Eventually, you'll get it backed all the way down to an idle and it will be super smooth. Thats what you want. No mid range gurgle or missing.

When you get the low end set--you'll need to go back to the high end and check it. If you have to lean the low end a lot--usually that will effect the high end too and make it lean. So, if you made more than 1 full turn lean on the low end to clean it up--you'll most likely have to go back and richen the high end again.

Set your high side again. Set it to max and then back it up the thickness of the slot in the top of the screw. About 1/16th turn. Not more than 1/8th turn. It's not necessary to run it rich like a glow engine.

Thats the only way I know how to tune them. It works, but it's time consuming.

Somebody is going to tell you that you'll fry the engine by running it up to full throttle on the ground and letting it run 1/2 throttle for extended periods of time. Total BS as long as it's got air moving over it. If the cylinder is sticking out the cowl and you got prop blast on it--no problem.

Make adjustments with the cowl on. If you get it all tuned up without a cowl--you'll just have to do it again after you put the cowl back on. The cowl effects the way the airflows into and around the carb. Leave it on.

An engine that surges up and down at high speed is lean. Richen 1/4 turn and try it again.

You forgot to tell him to let the engine warm up a little before he starts on the needles. Cold engines don't adjust the way you think they are adjusting. We'll have to spank you for that, ya know...

When I talked to Dave at DA yesterday he said they had considered shipping the engines with the needles in a bag, but relented...Think what THAT would do
I think if you actually READ the instructions it says the factory settings are a suggested STARTING point....
A G62 runs 400 to 500 rpm slower here at 7000 feet than it does in Phoenix at 1000 feet...

SO you actually talk to Dave at DA????[sm=lol.gif][sm=lol.gif][sm=lol.gif]
Do not let the Zenoah VS DA combatants hear that, lest they comit suicide!![sm=wink_smile.gif]

I just emailed DA a few time yesterday and got back responses same day.
Ordered a new DA100, cans, prop yesterday from LHS.

Prompt service.

Tony

Thanks for the updates guys. I understand that the factory settings are not where I will end up eventually but since I had good idle and reasonable transition I left it alone while I ran some fuel through it. RCPilot thankyou for taking the time to describe in detail the best way to tune the engine.

Oh my gawd, he is a spy [X(]

A minor detail. [sm=red_smile.gif] I ASSumed he would have it warmed up after he started it and ran it up to WFO for 15--30 seconds.

SS is right -- give it a minute or 2 at idle to put a little heat in the cylinder and then rev her up a bit to get it up to proper temp.