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HelicopterEngines Plugs Mufflers Fuel › Problem with OS 37SZ-H
06-03-2013 12:27 AM  4 years agoPost 21
dkshema

rrMaster

Cedar Rapids, IA

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Guess those two stroke motors I've been dealing with since about 1964 haven't done me a lick of good.

Where does the air leak occur around the main, rear bearing, please enlighten me.

The front bearing is wide open to the atmosphere, no seal, there for sure.

The seal at the front end depends upon the fit and tolerances of the front end of the crankshaft, and the crankcase, typically the portion between the front of the crankshaft intake port and the rear face of the front bearing. The front bearing plays no part in providing an airtight seal for the motor. The front bearing gets its lubricant from the oil in the fuel, some of which may leak out the front bearing. Some motors have a small groove cut in the crankshaft forward of the front of the intake port to make sure fuel/oil does make it to the front bearing.

The rear bearing, does not have an airtight seal.

You may not want to argue facts, the only problem here is what you state as fact, isn't.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-03-2013 04:18 AM  4 years agoPost 22
balsabasher

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Central Ohio, USA

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"The seal at the front end depends upon the fit and tolerances of the front end of the crankshaft, and the crankcase."

So with bad bearings whipping that crank around, what does that do to the fit and tolerance, not to mention the oil film that provides the seal. If this was not important why would you seal the backplate? Think about it.

Fact and experience, not opinion. So I am done with this discussion.

Blades; what goes around, comes around!

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06-03-2013 05:04 AM  4 years agoPost 23
dkshema

rrMaster

Cedar Rapids, IA

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Experience differs. I've had quite a few rear bearings in OS 50s and YS 50s, as well as an OS 70 that have gone bad. Leaning out as the motor went downhill was not noticeable.

Loose backplate offers several routes for air leaks, around the circumference of the rear of the crankcase, as well as the fact that several of the holes for the backplate bolts are open clear through into the interior of the motor.

Andy's motor is new. Very few actual flights. The rear bearing of the OS37 SZ-H is not one of those that has been prone to failure, as has been common with the larger 50 - 56 sized motors.

I still vote for inexperience in nitro motor tuning and/or fuel feed problems. The hoof beats heard here are from horses, not zebras.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-03-2013 06:08 PM  4 years agoPost 24
fla heli boy

rrKey Veteran

cape coral, florida

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my GUESS is still a carb not fully seated on the o-ring or a possible leak at the backplate......
I like Zebras...

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06-03-2013 08:02 PM  4 years agoPost 25
Andy from Sandy

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Bedfordshire, UK

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It has been explained to me that once the back bearing has gone noisy if it is not changed it can cause the crank shaft to move up and down which could result in the liner in the crankcase or the crankshaft wearing around the inlet port. Once that happens air can be drawn in causing a lean mixture condition.

If the bearing has gone it ought to be fairly noticeable but maybe for someone new to nitro they might not know.

The carb on this engine being held by screws in either side doesn't have
the same facility to squish the o-ring so if that has gone it could allow air in. Similarly if the screws are not done up correctly they to are a potential for an air leak.

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06-03-2013 08:35 PM  4 years agoPost 26
fla heli boy

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cape coral, florida

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I see that now. My old 32's used to just have one bolt that "pinched" the carb on to the body.
Just got a new Gaui with this motor, so I'll be getting more familiar with it.
My old 32's were the most reliable and easy to tune motors I ever had.

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06-03-2013 08:50 PM  4 years agoPost 27
Andy from Sandy

rrElite Veteran

Bedfordshire, UK

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My old 32's were the most reliable and easy to tune motors I ever had.
I believe it to still be the case when compared to the OS 37. Others may differ of course.

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06-08-2013 01:00 AM  4 years agoPost 28
HeliNutAndy

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worcester, MA USA

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It's been rainy this week but tomorrow it's supposed to clear up and I'm hoping to finally figure out what's going on with my model. If I remove the blades and run the motor will I do any damage to the engine or the model? I have done it in the past but I have kept the rpm to a minimum. I'd like to attempt to mimic flying rpm to see if I can reproduce the problem after changing the plug and adjusting a few things. The main blades, main gear, clutch, and tail gears all spin smoothly so I'm hoping all is well.

TIA,
Andy

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06-08-2013 01:05 AM  4 years agoPost 29
dkshema

rrMaster

Cedar Rapids, IA

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Don't run the motor up to "flying rpm", with no or little load, the motor is prone to over speed and that can trash the motor in an instant.

Make sure that while you are tuning the motor, to remember to disable the governor. Only have the governor enabled after you have the motor tuned correctly.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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06-08-2013 03:09 AM  4 years agoPost 30
HeliNutAndy

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worcester, MA USA

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Ok thx. I will have to bring the model to the field. It is just a little bit easier to work on the helicopter at home rather than the field. I have been dying to fly this model again

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06-08-2013 12:53 PM  4 years agoPost 31
fla heli boy

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cape coral, florida

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mine's been sitting here waiting to be set up for a week now.

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06-08-2013 01:25 PM  4 years agoPost 32
HeliNutAndy

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worcester, MA USA

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mine's been sitting here waiting to be set up for a week now.
Get that bad boy in the air I am just charging some batteries for my 550 and then I am off to the field.

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06-08-2013 02:44 PM  4 years agoPost 33
fla heli boy

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cape coral, florida

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I hear ya. I've got so much stuff laying around here. 9 helis, 1 gas plank, 1 badass electric plank, 2 foamie planks and a new quadcopter that I just unboxed.
They all need something done other than my 4 small helis.
Just so busy with work.....One of the downsides of working for yourself and working at home....
Out of everything, it's the Gaui I'm most pumped up for to get in the air.
I miss my old nitros from back in the day....still not sold on e-helis.

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06-08-2013 05:54 PM  4 years agoPost 34
HeliNutAndy

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worcester, MA USA

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I just got back from the field and I am disgusted with this model. After adjusting the motor and not being able to fix my original issue my clutch broke. This is the second clutch and my third clutch bell and I have only flown this model about 25 times. I only have one larger electric model(Trex 550) but since I have flown the nitro I like the nitro much better. I have gone over this model multiple times and I am just tired of it. I understand everything needs to be aligned properly but I have tried every trick I have come across to get this thing flight worthy with no luck. The day I got it I noticed the head assembly did not fit on the main shaft and I have been chasing issues down ever since. I am starting to finally understand why most people are going to electric because this is ridiculous. I will never purchase a GAUI model again. Good luck getting yours going.

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06-08-2013 07:45 PM  4 years agoPost 35
wrongler

rrProfessor

Brewerton, New York

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Wow, I know it really sucks when you work on something and can't make it right. Is there anyone at your field that can help?

Bill Whittaker

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06-08-2013 08:35 PM  4 years agoPost 36
adamsz06

rrVeteran

Geilenkirchen Germany

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Andy, I've followed your posts for over a year, and I'm not saying the model doesn't have issues, but it's been suggested many times for you to find some other people to fly with and help set up your model. I commend you for havng enough understanding and persistence to get your 550 flying and sorting out it's issues, but your first nitro is an entirely different experience. I'm not saying you cant figure it out...but you'll save yourself a whole bunch of frustration and money by finding some friendly and experienced people to spend a weekend flying with, even if you have to drive a bit to find them. One on one time will let you learn little tips and tricks and give you the benefit of having a second set of eyes look over your first nitro build. You'll be surprised how many times you'll say "why didn't I think of that", or "thanks for catching that before I got it in the air". I think you're gonna enjoy this hobby for a long time, but as your first nitro, get some help. The only downside with the forum is that people only ask for help when they know something isn't right. Until you get some experience with different machines, just because it looks right on the workbench doesn't mean it is. Being able to see other people's machines in person will help you ask the questions and find answers that you can apply to your own models. Runryder taught me a lot, but the things you learn at the field are priceless.
Good luck!

R.I.P. Roman

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06-08-2013 09:18 PM  4 years agoPost 37
fla heli boy

rrKey Veteran

cape coral, florida

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+1 on getting help. Don't give up!!!

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06-09-2013 04:13 AM  4 years agoPost 38
Nasty1

rrApprentice

Enf,Ct-USA

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Andy, bring that nx4 to the central Ct fun fly in Ct on Sunday June 9th, we will get the kinks worked out for ya.
Just ask for the nx4 guys at the raffle ticket area.
Mike

Empire Hobby Team Gaui USA

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06-09-2013 02:22 PM  4 years agoPost 39
HeliNutAndy

rrKey Veteran

worcester, MA USA

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My clutch is broken and I do not have a LHS where I can purchase one today but I am packing up my truck now and I am taking you up on the offer. I have never been to a RC event and I am looking forward to it. I hope to see some of you there

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06-09-2013 02:48 PM  4 years agoPost 40
wrongler

rrProfessor

Brewerton, New York

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Your gonna Love it!

Bill Whittaker

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HelicopterEngines Plugs Mufflers Fuel › Problem with OS 37SZ-H
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