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Evolution .60 2 stroke help

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gazzazh19/06/2010 14:18:25
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Hi All, I had 7 dead sticks today, and have been able to save my P51 on several occasions, but I don't want to risk it anymore. So I need your help. My new evo.60 engine is giving me hell. The break in process went well, the maiden flight went well, but all the other flights after that ended with a dead stick. When running the engine I can see bubbles in the fuel tube going into the carb. I have tested the tank and tube for holes or leaks but their is nothing. These bubbles lead to inconstant fuel going to the carb which in effect brings the engine off.. What should I look for? Thx
David Davis19/06/2010 17:48:59
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1, Make sure that your carburettor feed pipe is connected to the clunk and not to one of the tank's vents.
 
2. Check for pin holes in the pipes which would allow air in.
gazzazh19/06/2010 17:54:09
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Thx, I will check and keep u updated Cheers
Engine Doctor20/06/2010 11:10:10
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Hello Gazza . Air bubbles can also be caused by air being sucked in through the needle valve . Remedy is to fit a new "o" ring. Faults in the fuel pipes in the tank will only become evident when the fuel level get down to about half a tank and the pipes inside the tank are exposed to air. Does youre engine run ok with a completely full tank? If so it is more than likely to be the pipes leaking air.   Provided the fuel lines and pipes are OK check the following .Bubbles in the fuel can also be caused by vibration . This causes the fuel to foam = bubbles = air = weak fuel mix= dead stick. Have you  checked  the prop/ spinner for balance ? If thats ok , Is your tank mounted in foam ? Foam around tank should be firm enough to hold tank in place but soft enough to absorb the majority of vibration ; so reducing fuel foaming . Some fuels include an anti foaming agent . If you cant find out weather or not your fuel contains this then A small spray/few drops  of silicone furniture  polish or silicone dash boards treatment added to your fuel will stop foaming . You may be unlucky and have an unbalanced engine . I have seen these crop up over the years and theres not a lot you can do about that . Hope this pints you to the fault .
 
Regards
 
E.D.
Braddock, VC20/06/2010 11:26:15
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I go along with what's already been said, a few extra gotchas that may be worth checking.
1 are you using the same plug you used when running in, try substituting a new one.
2 is the fuel fresh, if more than a few weeks old try substituting fresh fuel.
3 is the exhaust pressure line hole free, connected and clear and is the open end of the pipe well clear of the clunk in the tank. Make sure that the fuel feed pipe from tank to carb is as short as possible as if not it can whip around when airborne and cause deadsticks.
4 if the tank has brass or copper pipes they can corrode VERY quickly and leak, the solution is to fit either plastic or aluminium pipework.
5 and finally if you have a filter in the fuel feed is it both clean and sealed correctly? Do not fill your tank with the fuel filter in line with the pumped supply, if you have done this then it's quite possible that the crud caught in the filter is now in the carb somewhere.

Edited By John Gibbs on 20/06/2010 11:28:03

gazzazh20/06/2010 13:25:28
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Thx a million all, I am currently on a business trip and will be back on the 27th.. As soon as I get back I will test all your suggestions and let you know. Thx again Cheers
Braddock, VC21/06/2010 20:33:33
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Pity really, you're missing all the good flying weather
gazzazh29/06/2010 21:41:40
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187 forum posts
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Hi All, So i checked all my fuel lines, and changed them, i also check the tank.. And went for another flight today, the first flight went very well... But the second one I had problems shifting from idle to full throttle. I tried to tune the low speed needle but without a y success, I also changed my plug just to make sure... Don't know what else to do. From my frustration I ended up injuring three of my fingers while trying to set the low speed needle... Any suggestions please. Thanks
Wingman29/06/2010 21:42:54
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1148 forum posts
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Yep - don't put your fingers in the prop
Steve Hargreaves - Moderator29/06/2010 21:51:54
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As Wingman says keep your fingers out of the prop.....you should always stop the motor before adjusting the idle mixture. The action of turning the screw will alter the throttle rotor position leading to inaccuracy.
 
Hope the fingers get better soon......!!
Lee Smalley29/06/2010 22:17:11
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gaz does your engine quit on a fast transition from a prolonged idle or does it just splutter for a while until its cleared ?
gazzazh30/06/2010 10:34:59
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187 forum posts
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Hi For the first flight, the engine run like a charm.... After I landed I found that the muffler was a bit loose.. So I tightened the muffler and started the engine again... It idles fine, but o. Transition it will splutter and die.. On slow or fast tradition it dies... As soon as I reach mid throttle range it dies.
Myron Beaumont30/06/2010 11:15:54
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5797 forum posts
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gazzazh
Having read about this problem of yours, I summise that the engine ran OK with a loose muffler after running it in on the bench Was it maybe loose when you installed it in an A/C . Now then, after that it kept cutting out .That leads me to believe that it's some thing to do with mixture settings versus tank pressure from the muffler ? Did you reset your mixtures after tightening up your muffler joint ? As others have pointed out ,there could well be a pin hole in a pipe somewhere .
 
 
John Gibbs
By the way ,I'm still using fuel about 3 years old .No probs ! You did mention fuel being a few weeks old as being dodgy
A leaking O ring on your needle valve would not cause bubbles in the feed line either. On the contrary.You wouldn't see them as any bubbles/air would go straight into the intake thus maybe weakening the mixture .
gazzazh30/06/2010 14:01:54
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187 forum posts
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HI, 
 
I checked the pipes and they were all tight, with no leaks, and just for the sake of it i changed all the pipes to eliminate this as a problem.
i believe that as you mention, its has to do with the mixture setting versus the pressure from the muffler... the question is .. how to fix it... I am fairly new to this hobby and have no idea what is the procedure to go thru.. your suggestions please.
 
thank you
 
Myron Beaumont30/06/2010 14:47:15
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5797 forum posts
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Gazzazh
One thing you can do is what we call "lapping in" the muffler joint . That is to say,use a mild abrasive between the surfaces rubbing in a sort of figure of 8 motion so that eventually they end up perfectly flat (making sure none goes into the cylinder of course .) .If any distortion is not too bad ,then Brasso or "T-cut "will do it .If severe then rub the muffler on wet& dry paper in the same manner (about 800 grade ) .I doubt the cylinder head / exhaust outlet  is distorted .Stick some cotton wool or similar in the outlet before doing it ! You shouldn't need any gasket after this .I never use one ,
Hope this helps -At least you'll have eliminated one possible cause of your problem (assuming the nipple is not leaking on the muffler that is)
Myron --Good luck
gazzazh30/06/2010 16:28:59
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187 forum posts
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Dear Myron, 
 
thank you for all your help.. i think i understand what your saying... or i hope i do.. so will work on that and let you know .. cheers
 
gazzazh30/06/2010 17:59:51
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187 forum posts
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i am sorry but what a "t-cut"
Myron Beaumont30/06/2010 18:30:59
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5797 forum posts
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Ahh !  T-Cut is a lightly abrasive liquid used for rubbing down paintwork on cars to get rid of grime/oxidation/scratches etc . It's very mild in texture . You could use that powder toothpowder for smokers I suppose instead .By the way,I didn't say how to rub down the manifold flange properly thinking about it . It's best done using a sheet of glass ('cos it's flat) and laying your wet & dry paper on it (use it wet & it won't clog up too much especially it you add a drop of Fairy liquid )  If you think it is badly distorted you can always resort to grinding paste used for lapping in valves on motor car engines using glass as well as a base
Myron 
Myron Beaumont30/06/2010 18:37:38
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5797 forum posts
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PS
I would not use a paper gasket on an exhaust .It partially prevents heat transfer away from the cylinder .Copper would be OK or maybe aluminium which is more easily available  eg Drinks can .
gazzazh30/06/2010 18:45:56
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187 forum posts
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thank you so much for all your help, i will work on it and see what happens ... thanks again for all the support... cheers
 

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