raptorhelis

I have a 3W-240 gasoline engine with a Johnson header (M185-S) and a 36-14 prop. It has a CDI ignition and I am running superklots 2cycle oil at 40:1. Everything was bought from Cactus Aviation and I can not get a reply from them. This was a barely used setup I got from a friend and it has only an hour or two on it. I bought it knowing that it had problems but I thought that since it was new I could easily fix it. The exhaust pipes were cut down three inches on each pipe so that they would be flush with the cowling. I didn’t cut the pipes they came that way. The problem is that the engine runs like crap and has a hard time running for a full ten minute flight. I have replaced the spark plugs, cleaned out the carb and put the engine on a test stand and have a strong 6volt power supply running the CDI’s and they are 6volt CDI’s. There is a strong spark but one other weird thing is that when I adjust the high speed and low speed air/fuel mixer screws it takes about 2 seconds before the engine changes to my adjustments. I know that these engines don’t change imminently but I think that it shouldn’t take that long. The adjustment screws are very sensitive when I am getting at the top of the adjustment where you are leaning it out. The engine will either die or run rich and rough. I am just getting into the very large aircraft I have been flying glow fuel airplanes and helicopters for a long time and also small 30cc-50cc gasoline airplanes. I know that the exhaust system can make or brake an engine so is there a better exhaust that will make it run better but more importantly give me more power. The CDI is a dual setup with two spark plugs per piston and each spark plug is connected to one on the two CDI ignitions so that if one spark plug or CDI fails the engine will still run. Any ideas or tricks would be very helpful and also around what rpm should the engine be running at full power on a test stand? Thanks in advance and I will keep updating this as I keep trying different things so that this might also help other people with engine problems. Thanks again Bryan.

ben beyer

My Feedback: (23)

I would give Gerhard at Aircraft International a call and talk to him about it.

JohnVH

My Feedback: (38)

Id think this would be better placed in the engines forum personally, but do you have one of those 3w carb horns on there? Seems they need them to run right typically.. course the 3W i had didnt run right even with it. Im not sure that cutting the pipes down will make that much of a difference on how it runs, Ive seen alot of them cut like that. Sounds like maybe an air leak somewhere? Can you send it in to another 3W repair place?

good luck!

j

DKjens

My Feedback: (50)

Is the prop you had with the engine the Bolly Carbon 36x14? Whether it is or isn't, your first sstep should be finding a smaller prop. Unless the engine will swing the prop at 5000-5200 on the ground, it will not be happy and will probably get warm in the air. I don't have any experience with the carb. that's on this engine, and unfortunately just getting a new one will cost you $300.00 or there about. I would take the carb. apart (very carefully) and clean each diaphragm and circuit.
When you say Johnson header, do you mean Johnson muffler? If you are just running it on a short header, it won't idle very well, but the length of the stacks on the muffler doesn't have a great influence.

What do you have the engine in?

DKjens

Tired Old Man

My Feedback: (1)

DK,

That engine should be able to effectively swing a 34-36" prop. Sounds to me like he has an issue in the carb.

DKjens

My Feedback: (50)

Silver,
Yes, but a 36x14 is not like any other 36x14. There are huge differences in load from one manufacturer to another. Look at the MSC36x15, supposedly one 1" larger pitch, but a prop they use on the zdz420b4, a much larger engine. I was just pointing out that the engine has to turn 5-5.2k minimum to be happy.

I understand you fly those 300lb 3W240 and Herbrandson290 powered turds around some times too. I know those 240 run pretty well in those airplanes, I suppose they get run in pretty much on the first flight with 30 gallon fuel tanks he he.

DKjens

Tired Old Man

My Feedback: (1)

I see your point with the prop differences. The 240 doesn't run all that well in anything.... As for the rest, I don't know what you're talking about. You're clearly hearing all that from someone else I USED to fly those antiquated pieces of junk[8D] and moved on to something LOTS better quite a while back. Pass that last on to our "rep" for a snicker or two[8D]

Antique

My Feedback: (4)

My 289cc Herbrandson powered plane goes 230+ mph...Try that with your 3W
Pretty good for an antiquated piece of junk....

DKjens

My Feedback: (50)

Ralph,
I think Silversurfer was referring to the airframes I was hinting at. My Herbie280 runs much better after putting the WB39 on it, but I still don't know if it's enough carb. I am going to try two carbs on it next and see if I pick up additional power.

DKjens

Antique

My Feedback: (4)

Yours is race ported, probably would work better the way you use it if the cylinders were stock..Wanna try some ?

Tired Old Man

My Feedback: (1)

DK,

You wre dead on in reference to the airframes. Ralph is gettin' too fast on the trigger today

Supermod56

My Feedback: (36)

The 240/275 doesn't use a horn. Bill Hempel ran a 240 forever on the Bolly 36X14 and got around 5200 if I remember correctly. More than likely you have a air leak or something else going on with the carb. I would send it to Gerhard at Aircraft International, he figured out why my 200 wouldn't run, the crank hub had slipped, so there is something else to look for, retarded timing.

Tom

torquen

Try giving Cactus a call and speak with them in person. Sometimes they are backlogged on their emails and dont always reply. But it sounds like you may not be getting the right amount of air intake into your carb. This is a rear intake engine and it requires a lot of air to run. The 240 will swing a 36x14 without a problem. I flew Bills 50% Edge in the half time at the TOC with the 240 and a bolly 36x14 and it ripped the snot out of it. More than likley you need a carb rebuild kit or more air into your carb area. You may also have a leak somewhere around the carb spacer.

pitts s2b

My Feedback: (138)

Gas mix on Wed 50-1to 80-1