OK, 3rd yr flying. Not an expert, but know internal combustion engines. First Gasser was a 3W-150. Ran great, never touched the needles. Got a 3W-100 I have more adjustment issues than you can imagine. Get it running perfect on the ground and it boggs, gurgles and sputters in the air. Finally sent it back to Cactus. Jury is still out.

Just received a brand spanking new 106. A real freeking power-house! First four runs, the engine felt progressively fat each run. Leaned top end out about 1/4 turn. Perfect! One week later, the engine wont get any RPM, felt lean, bit my finger on the prop spin BIG TIME issues. Dinked around and got is perfect on the ground. Nice slow uniform idle, SNAPPY response, smooth and nice RPMS. To the air I go... The POS ran like CRAP. Totally way too fat. Barely got the thing in. 1/8 turn leaner, 1/8 turn, 1/8 turn... Five or six flights and I finally gave up! Could not get it right.

Is there a recipe to this, I must be totally tune disabled!! What am I doing wrong!

Are you using the 90 degree intake horn? If not, get one and plumb the diaphragm vent tube to it.

All gasser carbs behave the same way. The low end mixture screw is effective over the entire throttle range. The high end mixture screw is effective only above half throttle. Adjust the low end mixture for snappy acceleration from idle to 1/3rd throttle. Then adjust the high end screw for max rpm at full throttle. Make sure the high end mixture is on the rich side of max rpm. Test fly and listen to the engine in the verticals at full throttle. If it sags or slows down richen the high end mixture 1/8th turn and fly again...repeat until it pulls hardest in the verticals at full throttle. Then fly it around straight and level at various throttle settings. If it is rich and burbling excessively, note your corresponding throttle position. If it burbles at 1/3rd throttle you need to lean the low end mixture. If it only burbles above 1/2 throttle, then you need to lean the high end slightly.

kool, I'll give it another shot. I have the vent tube into the fuse. No snorkle.

Why would it run great one day, and barely at all another. Pretty much same weather con., same field, same fuel...

Try putting one of Shawn's carb plates (RC Blimpro) on the carb over the diagphram breather hole. That will keep airflow at speed directed around the carb instead of right at the hole causing the engine to go rich in flight..... I like these better than a soldered on tube ......some planes inadvertantly pressurize the inside of the fuse causing you to think the diagphragm is safely vented and the plane will still run rich..
The 106 I had was a real barnburner but it was also sensitive to restrictions in the fuel inlet line(tee fitting for tank filling and inline filter) After I switched to a regular clunk straight thru to the carb ,the engine quit struggling in uplines and REALLY made some power!!!

Hope this helps, Dave

If the engine changes the way it runs and the weather is constant, then something else is changing. Check everything inside the fuel tank and all the lines, the carb mounting bolts, the reed block bolts. Mike Glavin e-mailed me that some of the 106 motors have an ignition that gets inconsistent in the heat. Talk to the distributor - maybe you need a replacement ignition.

Some things I have done so far. Please keep in mind I am having these same typ problems with my 100 and 106. I am pretty sure it is something I am doing...

Ign. is mounted on 1/4" grommets on firewall for ventilation. Diaphragm is vented into fuze, no snorkel, carb is openly exposed to air flow, Using Lawnboy ashless 50:1, Slimeline large dia in line filters...

I will try snorkels an see what happens. I just dont understand ho ground settings go to hell in the air and how a perfect running engine goes to hell in a few days. I'm going to pull the tanks also.

We tweaked and tweaked this thing today. Set it so it runs like a top on the ground, get in the air and it turns into a dog. We had two of us holding the airplane off the ground at full throttle, pointed it up, just like small planes, ran great. Took off and then ran bad again.

We adjusting everything everyway. What is wrong with these two 3W engines? Doesnt matter if its got a cowl around it or not.:thumbdown: Oh well, the DA100 will cure it

I am running the QS106 and it's perfect. Either try the snorkel, or try running the tube to the carb venturi instead of in the fuse. I tried this on my old 140 and it runs perfectly in all attitudes and throttle settings. I'm not sure this is a 3W or DA issue as much a carb issue in general. I have several pictures at home of the setup if you like.
Where on the rcblimp site are his carb baffles? I can't seem to find them. Thanks and take care_bob

Well... I found that setting the top end sooo rich it will barely run on the ground made flying much better Never had one like this before. Bottom end runs fine, top end is about 3/8 rich, so much she blubbers and chokes all over on the ground. needles are VERY sensitive. Once its 6" off the ground, pretty good. Gonna try a snorkle I guess.[&o]

Tuning an engine on the ground is commonly regarded as the standard. It really only provides a base line to start with. You have to remember in the air things change i.e., air pressure in the cowl, which effects several things and there is phenomena known as prop unloading!

I believe Diablo has given an accurate description of what it takes to tune our gas engines. Remember tune for maximum RPM and back up at least 300-400rpm... This will allow the prop to unload without the engine going lean. Fly it, pull verticals and learn to listen to the music of the engine. This is a MUST! Especially with engines that maybe under-propped...

Personally, I usually tune 3W's and DA's with a 15 lbs sledge hammer

Seriously, you are running into a pressure problem inside the cowling, making the pressure regulator inside the carburetor change position and affecting the mixture once you get a lot of air passing through the cowl (when airborne). Best bet is to isolate the diaphragm assembly with a breather tube into the fuselage, or by using a block-off plate or one of the 3W intake horns. All three methods work well. It's also a good idea to prevent any direct airflow against the carburetor by using an isolator plate to protect it from the incoming air blast. I do this by keeping the bottom of the cowl closed, and the cooling duct work keeps the air coming in from the front inlets from getting down to the carb and causing a problem.

Were going to start using a sledge for these 3W's too, this makes two that dont run like normal engine[:'(]

We are tuning with no cowl right now just to see if we can get it to run right...which is a pain at this point. But we are getting closer, never touched a finicky engine like this before[:@]

It has the breather tube into the fuse..

Well, got my 100 back from CA. A real helpful "resealed the carb base" note attached and nice "bench fee", what ever[&o]. Spent a nifty $80 on two 90 deg air horns. They did make a difference in that the tuning, on the ground is closer to being the same tuning in the air. That is to say I set the rpms on the ground and they stay some what similar in the air. Was a REAL problem previously.

The 100 ran really crappy (what a surprise) and sluggish once airborne. The Bench fee was well worth it! I'll continue to F around and think it may be OK. I spent most of my day getting just as mad with my NEW 3W-106. As I mentioned, the horn made a difference, however, I cant get it lean enough on the top. RPM's around 6000 and real rough sounding. I am set at 2/3 turn open on the top and am afraid to go further. CA generously sent me a new ignition, but no help there either. It seams the horn has some mystical richness effect.. Not sure where to go with this thing. 3 weeks of needle chasing now...

Any one want to buy a 100 and a 106[:'(]

How many turns open for the low end needle? If it's too rich, it will effect the mixture at full throttle and you will be trying to compensate by leaning the high speed needle. I'd call up CA and ask if they actually ran the motor. If so, it may be something you are doing that they didn't do that is causing the problem. Good luck

Dale, you went flying today? Still not working right huh? Well, there is one fix, DA!

Ask them what kind of refund you can get

Diablo,

What about when you get a burble when you go inverted? Interested in your thoughts.

Dan

My experience with 2 different 3W-100 motors in an AW Edge is that the 90 degree intake horn plumbed to the metering diaphragm on the carb completely eliminates any effect of changing pressure in the cowl due to attitude or throttle position. The mixture is consistent and there is no burbling when inverted or knife edge or slow rolling etc. Before this, I used the tube in the fuselage method, which was not a good solution for the problem - engine still ran way too rich inverted and in slow rolls. I also have a ZDZ-80 in a H9 Cap. Despite being a rear carb motor, it went rich on one of the knife edges. I modified an aluminum velocity stack so I could plumb the metering diaphragm to it and also completely solved the problem. I would use this setup on any gas motor.

I agree with Diablo. Venting to the fuse is ONE of the ways to deal with this situation. My opinion is that this is more of a gas engine carb thing, than a 3W thing. Other than the horn (which I like very much) seems like there are three ways to tune out the burble in gas carbs. The one Diablo mentions, the plate over the carb cover that 3W lists in their literature, and the tube soldered to the diaphram cover with a line to the carb venturi. That's the picture I've attached. I've had to try a couple of different methods depending on the engine/plane setup sometimes before I found the magic wand. Keep trying and it will work out_bob[img]

I've been toying w\ a 3W100. Weeks of adjusting and complaining. My stepson really discouraged. He would tweak and turn low end and high end. I installed nipple and tube to the fuse. still twist and turn. Flight after flight,and it still would burble and back fire, cut out when inverted or by pushing the nose over.WELL here is my fix! Start over at factory settings (Low 1 1\2 turns out and the high end 1 turn out.)My engine would fly but sounded terrible. Make sure engine comes to temperature before a decision is made of which needle to turn. Peak engine on the horizontal line and let it come to temperature.Note where the throttle is when you notice the problem. If the engine gurgled and spit from idle to half I would lean the low end if it was from half to full I would lean the high end.Important note: When they say adjust a needle a 1\6 of a turn at a time thats what they mean! Do not try to get a bit more because it will BITE you!Guys once I started over an followed these easy rules this engine started to talk. Be sure to let the engine get to operating temperature before you decide how to adjust it. In a few flights you will be as happy with your 3W as I am with mine. Happy flying.

Would you be happier with two more? They are for sale now...

Kent, we tried little adjustments also, we went to factory and all around. Even with these nipple tubes and carb bonnets...sure is funny a buddies DA100 doesnt need anything but fuel and a battery to run and these need a engineer degree....Even after coming back from cactus they dont work.... There will not be any 3W's sold in our area for years.

Somebody please buy these engines from him!

DAVE
try bolting a plate on the back of the carby going down two inches ore so, it will stop the pasing air
sucking out the fuel like a badger spray gun does making the engine run lean in the air
Has fixed it on my 3w 106
Ernst

The numbers game. I agree with Kent. With proper care and studious attention to detail, we'll all have problems somehwere at some time. I am of the opinion that there are just as many flyers with ZDZ, DA, 3W, Fuji ad infinitum that are pleased as punch, and some that have just plain had it and won't ever buy XXXX brand again. I have a QS100, QS150, and an old standard 140 that are all 3W and all run GREAT!!
I am not saying that they are all perfect. Heck, nor are we_bob

Maybe you guy's need to look at your electrical instalation also as i have found
the plug that connects the censor to ignition module any if that gets wet or get's sloppy
will change the running of the engine as i have found out
if you use smoke or not check it out it could well be you been looking in the wrong places
much easyier to blame the product than the end user
ernst

Bob_nj has the correct cure for the carb fix!!! Both my twins ran the exact same way ( 3W ) and you could tweak the needles till the cows came home and it didn't make a difference any which way you turned them. I also tried venting them to the fuse but actuall had one stall and quit on landing one day so I didn't like that fix either. Since I have vented the diaphram directly over the carb with a slight taper at the end of the tube I haven't even touched the needles since the beginning of the year. The motor doesn't spit or burble in inverted flight or any other attitude for that matter, the motor runs like wild fire now,and I am completely satisfied,it was well worth the time and few penny's I spent versus the frustration and needle tweaking you can go through.