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RE: Cox surestart problem please help - 1/16/2013 1:37 AM   
combatpigg



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quote:

ORIGINAL: glowtime

Sorry to stray off the subject matter on this thread. I just opened a new surestart from its bubble pack to clean for a grace airplane i just completed. When i took the backplate off i noticed that the backplate is split (cracked) on both sides of the venturi where the spray bar goes thru. So i take it that this assembly is junk right!


Just send the bad engine to ".049 flyer" and the defect will heal itself before it even reaches him......
If the crack compromise the airseal that is on the engine side of the spraybar, then it probably is junk. If you don't run it, you stand a better chance of a refund. If you aren't worried about a refund, then you might as well see for yourself if it will run or not.

To answer the earlier question about spraybar orientation, it has been claimed that the outlet orifice will see the strongest vacuum if it is perpendicalar to the flow of air. My intuition says that the orifice should be slightly tilted past perpendicular....but I've never spent any time at a "flow bench" to see for myself how it should be done.
Study cutaway views of automotive carburetors to see what the consensus opinion is.


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RE: Cox surestart problem please help - 1/17/2013 12:59 PM   
Balda


 

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Hi, 

I think my surestarts are those Estes.  I always follow one of my friends break in procedure, using FAI fuel for the first tank, and continue break in with 25% nitro fuel. 
 compression seems low, and my new piston / cylinder that I ordered seems already lost in the mail . I re-order another batch and still waiting. 

-Balda-







quote:

ORIGINAL: GallopingGhostler

Just perusing this thread got me wondering if Balda got one of those Estes Sure Starts that was possibly made with a mishmash of parts from who knows what years in their parts inventory. Also I was wondering if Balda was using FAI (zero nitro) fuel.

Warren Leadbeatter, a Cox 049 engine collector and flyer has this blog article in E-Bay, explaining how to successfully hop up the Surestart:

http://reviews.ebay.com/Cox-Surestart-Hop-up?ugid=10000000005390559

The $6.99 US cost he mentions was a few years ago, when Estes was selling them on clearance prior to liquidating their entire Cox engine parts inventory.

It sounds like to me that as long as one doesn't overdo it, probably won't experience fuel draw problems, but YMMV.



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RE: Cox surestart problem please help - 1/17/2013 1:48 PM   
049flyer


 

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Status: offline 		Combat pig is right. Send it to me. I'll put a new $3.00 backplate on it and fly it on my 10 oz pylon racer. I'll even pay shipping!

Seriously, i have backplates laying around in my field box. Send me a PM if you want one. Take a pic and post it so we all can see the defect and I can be sure I have the right one for you.

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RE: Cox surestart problem please help - 1/17/2013 6:40 PM   
GallopingGhostler



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quote:

ORIGINAL: Balda I think my surestarts are those Estes.  I always follow one of my friends break in procedure, using FAI fuel for the first tank, and continue break in with 25% nitro fuel. Compression seems low, and my new piston / cylinder that I ordered seems already lost in the mail. I re-order another batch and still waiting. 

Sounds like the manufacturer mismatched the piston and cylinder for such a bad fit. You do not need to use FAI fuel for the first tank. The 25% nitro fuel should be sufficient, provided it has some Castor oil content. Castor oil is needed to protect the piston's ball and socket joint with the connecting rod, and protect the aluminum crankcase bearing surface for the steel crankshaft.

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RE: Cox surestart problem please help - 1/17/2013 8:46 PM   
aspeed


 

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Status: offline 		Balda, is the compression leaking, or just low.??  The low compression heads won't have much resistance when flipping over.  I would never use them unless the motor is just too fast for a specific airplane. ( I do have one TD with a single port cyl, and low compression head on an oldtimer plane because it was justt a bit much.)   If the piston is leaking bubbles out of the exhaust ports, then maybe the fit is bad.  I will say it again, the dished low compression heads are pretty useless, a TD head or one of the Russian or Merlin or conversion plugs are needed for any performance.

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RE: Cox surestart problem please help - 1/18/2013 10:46 AM   
GallopingGhostler



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Status: offline 		Oh, I suppose the low compression heads could come in useful if the owner wanted to run a larger prop like on a Texaco styled old timer airplane to reduce overheating. I haven't ordered any engines from them yet, but I think that Cox International out of Canada and a few others that purchased the Estes Cox parts stock are doing a much better job of quality assurance, product is more consistent.

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RE: Cox surestart problem please help - 1/18/2013 12:27 PM   
Balda


 

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Status: offline 		Hi all, 


  I ordered merlin heads and also cylinder and piston set, just too bad , I think already lost in the mail.

I already re- order the same item.  Yes, oil bubble can be seen at the exhoust port. Imagine that, i hold the engine by just holding the drive plate , and the cylinder  positioned at side way. the compression seems too low that the engine can't hold in this situation , the cylinder  pointed downwards in few second. 

the second sure start seems a little higher compression, but suffer from serious vibration problem. I broken in for several tank, although the rpm increased a little and vibration already gone, the rpm still in lower side. Out of curious, I cleaned the cylinder's innder wall which coated with sticky castor, and the vibration came back again.

Its fun to learn a lot of thing while experiment with sure start though. 




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RE: Cox surestart problem please help - 1/18/2013 1:45 PM   
GallopingGhostler



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Status: offline 		Usually vibration on these Cox engines is related to propeller not balanced. If you have a propeller balancing tool, it will reveal which blade is heaviest. Sanding on the back side of the blade will remove material to help lighten it and achieve balance.

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RE: Cox surestart problem please help - 1/18/2013 4:21 PM   
Balda


 

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Hi,

 I understand that unbalanced props will reduce efficiency. I balanced all my props before using it.   

 I noticed that after several tank of fuel the vibration reduced to normal level. If I open up the cylinder and clean the inner wall,  It will starts vibrate again, the vibration so strong that loosen the mounting screw. really weird.
I've seen someone in forum said that caused by cylinder and piston not fitting well and knockng around, once it really covered with thick polimerized castor, the vibration will stop. I don't know how true but it really happened in my case. I need to run at least 4 tanks ( 2 oz tank ) to make it running smooth again. once the vibration go away, RPM will increase by several hundreds. .



   -Balda-



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RE: Cox surestart problem please help - 1/18/2013 8:22 PM   
GallopingGhostler



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Status: offline 		That's interesting, Balda. I've never had a problem with that, but it's been a while since I have run anything new. Except for 2 Surestarts I bought from Cox, the rest are prior to the Estes ownership. Those Cox produced engines were high quality and consistent, ran well. I never experienced the type vibration you refer to, except for unbalanced props. Yes, that does sound weird.

You may already know this. You may need to reset the piston socket that holds the connecting rod ball. It requires a special resetting tool and a hammer. It reduces the play in the socket joint.

Oh, I just wanted to add, we had friends from Singapore here, they were stationed at the Cannon Air Force Base with the Singapore Air Force. Half moved to Luke Air Force Base in Arizona, US and rest back to Singapore back in 2004. Singapore is kind of crowded. Just curious where you are able to fly the .049 planes?

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RE: Cox surestart problem please help - 1/18/2013 8:41 PM   
combatpigg



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Status: offline 		Interesting that devarnishing the piston / liner would make the engine run rougher. I wonder if the ballsocket is tight..?
I can't see how the piston could be chattering against the cylinder wall..if it was that loose I doubt you could get the engine to fire.
When I ran TDs in competition they got treated to complete cleanings with a gun cleaning kit often and the ballsockets were checked after most flying sessions.
I rarely found the need to balance 1/2A props, mainly just trim the casting flash off some of them, especially the Grish Bros., "White Trash" props.


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RE: Cox surestart problem please help - 1/18/2013 10:23 PM   
aspeed


 

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Status: offline 		Sometimes the .051 cyl. make the reedies vibrate.  Is it one of them?  They have a tiny groove in the piston when you bring the piston to top dead centre.

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RE: Cox surestart problem please help - 1/19/2013 2:45 AM   
Balda


 

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Status: offline 		Hi,



   My friend help me to reset the piston about couple of weeks ago. The vibration still remains if I de-varnish the cylinder. . I use the same prop in my friends engine and no vibration with his engine.
I searchded and some users experienced the same , but can't tell why.  In cox engines forum, I searched " vibration " and people talking about this too.
I will KIV until I receive my new parts so that I can experiment with it to find out more. 

Yes, Singapore really hard to get a nice place to fly.  every Sunday, I need to drive about 1 hour to Johor, Malaysia. and meet a group of my friend there.  other than electric, they fly glow engines that not less than .46 size, and big gasser, and some even flying jet engines.

 -Balda-

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