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HelicopterEngines Plugs Mufflers Fuel › OS 70 SZ-H Motor HELP!! PLEASE!!!
11-24-2006 09:42 PM  11 years agoPost 1
dumbflyer

rrApprentice

Pembrook Pines, FLorida

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Ok! I have a OS 70 motor that has been mounted in a scale fuse!! I have tried everything, bit cant seem to get the temp down. I mean she is running in 300 degrees or so. This is my second piston ring. Am I doing something wrong in trying to tune it. She does not idle very well at all it sputters up and down. This is the 3 needle carb. 60B. I have all but put this motor through the window. is there anyone who can give me some tips.

Thanks

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11-24-2006 10:11 PM  11 years agoPost 2
BigBobby

rrApprentice

Yass NSW Australia

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If the motor is rich and still cooking up then either the fuel is poor quality or there is lack of cooling airflow over the engine.
Did you tune the engine in the heli without the scale fuselage on?
Is the cooling duct restricted in anyway?

A few helis, this and that

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11-24-2006 11:53 PM  11 years agoPost 3
dumbflyer

rrApprentice

Pembrook Pines, FLorida

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Man I tried everything!! I am beating my head against the wall!! Fule is CY wildcat 30 the only thing i can think is that it is getting some back pressure! i have it routed through the bottomof the fuse!

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11-25-2006 12:06 AM  11 years agoPost 4
Droid

rrElite Veteran

Deep down in the Southwest- UK

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What exhaust system are you using? Sounds like its choking the engine

Quotes may have been changed for my own amusement

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11-25-2006 12:53 AM  11 years agoPost 5
dumbflyerrrApprentice - Pembrook Pines, FLorida - My Posts: All  Forum  Topic

look at photos

This is what I have

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11-25-2006 01:27 AM  11 years agoPost 6
BigBobby

rrApprentice

Yass NSW Australia

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I had one of those. Got rid of it due to choking the engine. Unfortunately you may have to use it due to the scale fuselage. I suggest taking the mechanics out of the heli and try tuning the engine out of it.
Use new fuel, new plug, better exhaust, better ducting for cooling the engine,

A few helis, this and that

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11-25-2006 02:25 AM  11 years agoPost 7
jzeller

rrApprentice

Victoria, MN - USA

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Have you disassembled the carb looking for debris. Does the fuel filter flow ok (blow through it to make sure)? Is the clunk blocked? Are there any leaks in the fuel lines, especially the clunk line? Don't trust any part just because it's new.

John

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11-25-2006 03:21 AM  11 years agoPost 8
Tyler

rrElite Veteran

Chicagoland area

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Muffler

I would bet that it is the muffler. I have seen those mufflers complained about online many times.

Also, that long silicone extension really adds a lot of restriction to the exhaust. Could you get away with a simply Hatori exhaust deflector and send that out of the bottom of the fuse?

The OS 70 really likes a big muffler, 30% fuel, and Enya #3 glow plugs. The enya #3 runs much richer needle settings than an OS #8.

I have had great luck with Hatori SB-15's and zimmerman 60-90 mufflers on the OS 70's.

I actually have some Hatori SB-15's for sale that might be great for a scale situation, as they are not shiney and new looking any longer. They can also be rotated to fit scale mechanics due to the floating two piece design.

Tyler

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11-25-2006 02:04 PM  11 years agoPost 9
Dr.Ben

rrMaster

Richmond, VA, USA

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Tyler is right.

Get the largest chamber muffler you can fit inside the fuse. Also make sure your cooling shroud is a tight fit around the shroud. You would also do yourself a big favor by putting a fresh ring in the engine and then running it in just a bit on the bench. While I am NOT against running an engine in in the model and always do so myself, a scale fuse is often a wicked environment in which to force a new engine to work. A modest bench run will give some time for the ring to seat and allow you to roughly set the needles (just roughly, but a start).

And lose that long tube. It adds a TON of unwanted backpressure.

Ben Minor

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11-25-2006 02:22 PM  11 years agoPost 10
nivlek

rrProfessor

Norfolk England

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I ran my OS70 with a 90 size muffler , but I would be willing to bet that your main problem is that long extension . It would be worth sticking a drill up the end of the muffler to increase the outlet size , then sleaving the exit tube of the muffler to increase the outer diameter and fitting larger bore extension tube to reduce the restriction .

At the end of the day , it gets dark .

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11-25-2006 02:22 PM  11 years agoPost 11
dumbflyer

rrApprentice

Pembrook Pines, FLorida

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I think that is what I am going to do!! It looks like all that heat I lost some compressin on the motor! and I cant get it to idel properly anymore. Not shure what is going on there now, but i think I am going to have to get a new piston ring and break her in once more!!

Change the pipe! Ya see I was told that I can use this pipe cause i dont need anything special to run it inside of a scale fuse! I will try some of what you guy said and take it from there. I will keep you posted on my progress.

THanks for all you help and input

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HelicopterEngines Plugs Mufflers Fuel › OS 70 SZ-H Motor HELP!! PLEASE!!!
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