Dumb design

Feb 25, 2004 20 Replies

I bought a couple of Magnum 30 4s engines and was wondering why the idiot who designed it put the needle valve AND the muffler on the same side of the engine. Later, I saw the OS 30 had the same setup AND noticed that the Saito 30 is that way too.



DUH !



Anyway, I thought I'd remote the muffler using silicone tubing. However, I'd need a nipple to screw into the exhaust port - anyone know what the thread is??? Also need some hi-temp silicone tubing with a .375" ID. I did some web searching, and came up with too small (fuel tubing) and too big (car header tubing). Any ideas???



David


If the muffler is designed like the OS, you can take the muffler off the pipe and use the pipe as your header. Then use a too-big tube to avoid excessive back pressure. If it's not like the OS, cut the muffler off the pipe with a hacksaw or Dremel cutting wheel, then order a new muffler from your hobby dealer.

You cant flip the carb around? I thought that was standard with 4 stroke engines. Did that with my Saito .30's, my OS .52, and my Magnum .91, my father's Magnum .52, etc. Possibly these are your first FS engines. I honestly thought the same thing with my OS .52 which was my first FS engine. You should be able to remove the two mounting screws and flip the carb around.

A 4 stroke exhaust is much hotter than a 2 stroke's. I tried attaching some of the hi-temp tubing to the output side of a 4 stroke's muffler to get the exhaust out of a cowl, and within a few flights it would burn right through. Never could find any silicone tubing that said it would hold up.

O.S. (and others?) makes flexible metal tubes specifically for this purpose. Maybe one of those will fit your application? Also, you can make an L-shaped extension for your needle valve with some small music wire. There probably is a small hole and set screw in the end of the "knob" for the needle valve for just this purpose. That'll get your fingers away from the muffler.

Jack

snip I have a Magnum 56 and an OS 4s and to move the needle to the opposite side of the engine you simply unscrew the screws holding the carb to the case and turn it to the opposite side and put the screws back in. Did I miss something here? Maybe the Mag 30 is different.

Gene

Look at the picture here.....

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Notice the carb is a solid casting with the mounting flanges machined on the casting. So, no flipping the carb.

Also, the muffler is machined aluminum with a cut-threads nipple on the end. Magnum supplies a '45 knuckle' fitting that screws into the exhaust port and the muffler screws into that.

Assuming the OS30 header has the same thread, I could use that - at $13 though.

The major diameter of the threads is .390" - anybody got a book that can convert that to mm threads?

David

I've got 2 x Mag 30, 1 x Mag 52, 2 x Mag 61, 1 x Saito 72 and 2 x Mag

91, so I'm not a 4S newbee. The Mag 30 and 52 carbs cannot be switched !

David >You cant flip the carb around? I thought that was standard with 4 stroke

OOOOPPPSSSS - the 52 carb is switchable.

David

Actually, here's a better picture of the carb....

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David

Yeah, I guess you cant flip that sucker around. Hmmm... I think I need to recheck my FS engines. I know I flipped around the carb on at least one of em!

I stand corrected! :-) Sure getting tired of the taste of my own foot...

Dan, The Saito .30's don't rotate on demand. However all others in the Saito line do, as do many that copy the Saito design.

"most" is the key..... look above for a link showing the one piece casting of the Mag 30 carb.

David

"most" is the key..... look above for a link showing the one piece casting of the Mag 30 carb.

David

Man, im just looking worse and worse here! And I actually ran one of my Saito .30s too. Too many engines. Well, not TOO many...

Snip:

Take heart, "the one that dies with the most engines wins." (paraphrased from my wifes quilting news group.) Gene

I think I have the lead on dieing with the most engines! haha! I just can't resist 'em. I now have more gasoline engines than any sane person needs! I guess I need to build some airplanes around them, eh?

Thats kind of what I am in the process of doing. Getting tired of those baleful looks the engines in the drawer and boxed on the shelves are giving me.

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