i recently picked up a 4 stroke bi-plane for cheap. i'm goin through it right now and came across this. what do i do about this. please help. i dont know what you would need to know, so if there are questions please ask and i will try to answer them.

here is another picture

here is another. thanks for any help

If I understand your problem correctly it's that the carb sits too close to the firewall to connect to. This is very common with 4-stroke engines. Here is how you take care of that issue. First replace the cable with a stiffer pushrod. Then exit the pushrod out of the tube and bend it back around to the throttle arm.

Ken</p>

Chevy,

I am rigging a cable linkage for my TT 75 4-stroke on my Neptune seaplane. RCKen has a great idea if you have room, but I have the additional constraint of getting mine to fit in the cowl. This is important as I need to keep spray off the engine as much as possible. The cable (goldenrod brass cable) runs through the firewall just like yours. What I did was mechanically adjust the linkage for minimum travel by using the innermost holes on the carb linkage and electronically trim the servo to give me the required throw. I'll post a picture later, but you could practically walk to my house from yours and see it yourself.

First, it looks like you need a new throttle arm. I've not had good luck trying to salvage a broken arm like in the photo. You can get them at tower.

Iuse a like cable linkage, but I usualy have a ball on the throttle arm and have my adjustable screw on the servo. Your setup will let you get the throtle arm as close to the firewall as possible. My setup add's about 5/16" to 3/8" but I'veyet to find a situation that It didn't work.

My suggestion is to replace the throttle arm and the cable, The cable sheith may be OK, but you will never save that bent up cable.

A question, was the plane wrecked? I can under stand the arm breaking off the the servo was over travelling and it was binding at full throttle and full idle. I can't get my head around what may have bent the cable like that in the first place.

Don

the cable i bent. its not from a crash. i guess i need a new throttle arm. i will check tower.


thanks!

Will I need a new carb or is the arm a separate piece that is available.

Just the arm. The hub is held on with a set screw and the arm was attached to the hub. It should be almost a painless repair. They are under $10, and should ship for just a buck or two more.

What engine is it? All I could see was that it was a Surpass. We can tell you what the part is that you want knowing the engine is is on.

Don

this is the engine that i have

Hopefully its just an illusion, but it looks like your crankcase is cracked.

It definitly looks like a crack.

Just a broken throttle arm, I broke one once and it was just ordered from my LHS or Tower. If that is a small crack?? It can be repaired by cleaning it good with acetone then mix up some JB Weld, heat the case and heat the JB then with a finger push in the JB and let cure over night. JB Weld can save a lot of little things like that.
Don, 64 degrees and calm!!!!!

I will take closer look. I just a quick look with a pick. It didn't catch, but I will clean it and set some oil in the area and see if oil seeps through. I looked on tower for the arm but all I see is the carb.
Also another ? I have a confirmed good battery. When I flip the switch on, the servos twitch. When I try the controller, I get nothin. What should I check?

Click on the carb, then on the left side of the page is "Replacement and optional parts" Click it
and you get the parts for the carb. This is the part you need. http://www3.towerhobbies.com/cgi-bin...LXCW16&amp;P=Z

You can also use the number on the carb and at the bottom of the OS parts, is carbs. Find the right on and click it for parts for that carb.

Don

cool! thank-you very much!

First off, that's not a crack. It's just a ridge left by a seam in the mold.

Second, you can easily repair that arm.

The arm is pinched in place and yours has not broken, it has just come loose.

Note how the inner ring has 4 indentations (Picture 1). This is where the ring was mechanically pushed out to squeeze itself against the outer ring.

Put the outer ring back in place and tap the 4 indentations on the inner ring with a punch to push them out against the outer ring and you'll be fine (just make sure the arm is in the right position first).

Mike, take a close look at the ring in your second photo, It looks like it has been bent and twisted. Note that the arm is not coming off it square, but has been twisted. It looks like it has had some serious plier work on it. $4.95 is cheep insurance.

That style arm loosens up some times. Itake it off the carb, and use a small screwdriver as the punch and drive the flares back tight in the notches on the arm. My O.S. 52 four stroke has the same type arm and I couldn't figurre why the engine was not consistant around idle. I then noticed that the ring was chucking agack and forth on the hub. Loosen the set screw and then tighten thingsup on the bench block and you are good for another season.

I'm not a fan of using the punch on the throttle arm while it is still on the carb.It would be to easy to sip and cause some reall damage.

Don

Looks pretty bent to me too?? Around 70 degrees and calm, road trip to the LHS today, flying tomorrow!!! I have another new student so it should be a lot of fun!![X(][&:]
Gene

Sorry Mike, that is a crack and not a parting line in the mold. I have a feeling there is something wrong with the motor mount causing too much stress on the crankcase. Or, the plane was crashed.

Some years after I started using the four strokes I discovered I was supposed to be using aluminum mounts and not the GP adjustables I was using. That can crack a case. Surprised me but it was on an OS web site. I have never broken one but that's what it said could happen.

Well, I've enhanced the original photo and if there's a crack, I sure can't see it.

Photography is one of my other hobbies. I saved the pic and played with it some using post processing software. Check this look.

I saw that. It doesn't look like a crack. I am a digital imaging specialist and I also used to be a metallurgist and dealt with foundry castings often. It looks like a minor flaw in the casting, but nothing to be concerned about.

Looks like a crack to me. Nothing JB wouldn't cure though.