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Old Jul 08, 2009, 06:15 PM
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Old Jul 08, 2009, 07:59 PM
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Originally Posted by init4fun
Yikes ! Even too big for quarter scale ?
I have a 270 on an older scratch built 1/4 scale Lazer 200.
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Old Jul 08, 2009, 08:12 PM
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Old Jul 08, 2009, 10:18 PM
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Went out and weighed it. 14 and a half for the fuse. Didnt get the wings down. Prolly a couple pounds apiece. Call it 19 lbs with canopy on

I think it has an 18x12 on it. Im not sure.
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Old Jul 08, 2009, 10:39 PM
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Quote:
Originally Posted by MikeMcChiken
Hey James , I always drill nylon mounts so when I put the cap head screw in I have to screw it into the mount . Use a tap drill chart to get the right drill for the right screw . When you screw something into nylon it creates heat in the nylon which actualy makes it bond to the screw somewhat . I still use screws long enough to put a locknut on for extra security .
Mike:

Greatly appreciate your multiple posts on engine mounts. Real world experience and your pictures to document it are worth their weight in gold.

James L.
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Old Jul 08, 2009, 10:41 PM
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Old Jul 08, 2009, 10:58 PM
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Quote:
Originally Posted by Ed Cregger
I haven't found many sheet metal screws that are worth bothering with when using an epoxy engine mount. Goldberg had some (rounded shiny head) that worked perfectly for a while.

What I have discovered is that if you use the appropriately sized (small) body drill, you can drill through the epoxy glass engine mount and then tap the mount with threads for an appropriately sized machine screw (6-32 on the smaller sized engines). I have been doing this since the seventies and I have yet to have a mount strip its threads or for a bolt to come loose once properly tightened. Yes, I was skeptical when I first heard of it too, but you can't argue with positive/no failure results. I have built and flown many, many models since the late sixties and seventies.

If your threads are stripping out in your epoxy glass mount, your body drill is too large. Unfortunately, I don't remember the number of the body drill for 6-32 thread cutting.


Ed Cregger
Ed:

Thanks for pitching in on this subject, also. Before your and MikeMcChicken's posts, I kind of figured there were users of glass filled engine mounts out there who would choose not to use the included sheet metal screws. Your post backs up Mike's method as well. Without your and Mike's post, I would have just drilled through holes, but your technique makes a lot of sense.

Greatly appreciate your contribution.

James L.
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Old Jul 09, 2009, 12:40 AM
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Quote:
Originally Posted by init4fun
Yikes ! Even too big for quarter scale ? I was hoping to keep the airframe size down to something managable- the easier to get it to the field . I dont mind slightly overpowered but im not looking to build a hotrod fast plane . Imagine that . . . . most people usually have the problem of not enough power and here ive ended up with too much . Oh well im sure ill find something appropriate for it . And if not ? Well it wont be the first cub to get unlimited vertical Thank you and Happy Flying
My SIG Cub is covered with Coverite and Dope, has a complete running, landing, and Strobe light system, and wheel pants. It weighs about 20 pounds and flies excellently with the Surpass 120. It will loop from straight and level flight which a real cub won't. Takes off in less than 50 feet.

The 270 or 300 would be perfect on Balsa USA's 1/3 scale Cub
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Old Jul 09, 2009, 09:23 AM
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It's true, the 270 will over power a 1/4 Cub, but it will fly well, if you use some throttle management. By running the motor at lower RPMs, you'll be able to hear each cylinder as they fire.

The cylinders will protrude from the cowl, too !

I had a 300 in a 1/4 Taylorcraft. (15#) At full throttle, it was highly aerobatic, but when I throttled back she was very docile. You should see similar characteristics with a Cub.
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Old Jul 09, 2009, 10:40 AM
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Old Jul 09, 2009, 11:29 AM
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i have an .82 and a .56. i just started flying fuel a few weeks ago so it is very new to me. the .56 flies great but the .82 has gave me a problem. when i was breaking it in it would idle and up to 3/4 throt. it was good but at full it would rev higher and higher and then die like you hit a kill switch. sence it was my first engine to break in i didnt think much about it just went to 3/4 throt. when i put it in my plane i couldnt get to full throt for more than a few seconds before it it shut down. it gets very hot also. i finely checked the nipple on the muffler and it was packed with something i cleaned that and i dont have the problem any more. i have found that a lot of oil is comming from around the plastic back plate. i checked the screws and they were all loose except the one behind the carb. so i tightend them but it still blew oil. i removed the plastic back plate and it had no gasket as the diagram shows. i read in another thread that you may get some oil here but should the gasket be there and the screws be tight. it has gotten very hot but it hasnt froze up or lost compression so mabe i havent damaged it.
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Old Jul 09, 2009, 12:04 PM
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Dont bother greg, i think this thread is for bigger saitos? Mine also ran hot (the 2 stroke induction every stroke helps with cooling I think). Thats why I sold mine -I caught a nasty burn on the wrist & can't hear 4 strokes as well up wind (nothing to do with saito as it was an excellent engine).
cheers
Simon
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Old Jul 09, 2009, 12:32 PM
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Old Jul 09, 2009, 02:33 PM
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Quote:
Originally Posted by greg harrison
...... i checked the screws and they were all loose except the one behind the carb. so i tightend them but it still blew oil. i removed the plastic back plate and it had no gasket as the diagram shows. i read in another thread that you may get some oil here but should the gasket be there and the screws be tight. it has gotten very hot but it hasnt froze up or lost compression so mabe i havent damaged it.
Your running really rich at break-in and there will be lots of oil comming out of the crankcase ventalation . Saito changed the backplates from aluminum to plastic so the drawing might be for the aluminum plate . Plastic might not need a gasket . Maybe call Horizon to verify this . Maybe someone else here knows if the plastic back-plate has a gasket ?

I asume you have already ran a few tanks through it before putting it on a plane . Have you started to lean it out any on the top end ? How many turns out is the top end at . Where is the low end at ? Is it flush with the throttle arm ? Lower than flush , higher than flush ? What kinda fuel you using ?

Snorks , all motors get hot from running , 2 and 4 stroke . This thread is for all Saito's . As for not being able to tell where the motor is when you run it up , You need a Tach . This is the biggest needed tool for tuning a Saito properly . Tachameter .
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Old Jul 09, 2009, 03:19 PM
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You don't need a gasket on the back plate. 4 cycles in general run with the crankcase ventilated to the atmosphere. The only reason you might need a gasket is if it leaked too much oil which just makes a mess. The plastic backplates fit tight enough so oil leakage is kept to a minimum if any.

I have never needed a tachometer for any 4 cycle engine. I have been running them since I bought my first in 1976. The first model of the OS FS-60. I use a tach but just to see what RPM an engine turns a given prop.

I watch guys at my field spend hours tweaking and taching their engines needlessly. Setting a 4 cycle by ear is not all that more difficult than setting a 2 cycle.

A Saito is a Saito, big or small, so it would seem questions on any size would be welcome here.
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