Conference vmszoo::rc

    I'd try a bottle brush.  You'd have to build up an awful lot to make a
    difference in weight or performance.  You could scrape most of it out
    with a stiff bottle brush and you could make sure that the baffle holes
    are clear.  Why is he getting such a buildup?  
    
    Charlie
    

    Can't get a brush into the baffle to clean it. As for the reason for
    carbon in the first place thats a mystery in itself. For some reason
    his YS 45 2 stoke builds up a lot of carbon after only 10-12 flights.
    You can see it right on top of the piston. He thinks that there is even
    more carbon building up inside the pipe. He was right because using a
    brush to get inside the pipe a lot a carbon came out. The baffle is the
    problem spot. This is were there is even more build up but he can't get
    into the baffle to clean it. With all this build up he has been eating
    plugs after one or two flights. Theory is, if he can clean the pipe
    that variable can be eliminated than move onto the engine, fuel, etc.
    
    Dennis
    

    
    When I used to ride motor bikes we used to get carbon out of exhaust
    pipes with a solution of caustic soda in boiling water:
    
    CAUTION !!!!!!!!!!
    
    I have never seen this done with aluminium, try a test piece first? 
    
    DOUBLE CAUTION !!!!!!!
    
    Caustic soda is REALLY nasty stuff. It'll burn you before you know it.
    Wear goggles and long rubber gloves if you decide to try it.
    
    
    As to what the stuff is, sounds like burnt Wyesterone, eh Eric?
    
    Cheers
    
    Nigel
    

    Thanks for the input Nigel but it sounds like this may result in
    having to suit up with a nuclear waste disposal team. I don't think
    this pilot wants to got that far just for carbon.
    
    Dennis
    

    I blow torch the pipe to soften the carbon and then wash out with ammonia 
    solution whle still warm. Haven't done it for a very long time though.
    
    
    Evl-1

    Be careful with heat - it's very possible to melt a hole in an aluminum
    pipe!  I have hundreds of flights on my YS45 with Tuned pipe.  I never
    noticed carbon buildup but I did have trouble with some brands of
    plugs.  He's probably not got the pipe length tuned properly or using
    too hot a plug if he's blowing plugs.  Carbon has to be from the lube
    in the fuel.  I was using half castor and still not getting much
    buildup.  My piston top is clean after many hundreds of flights.  A
    short pipe is very hard on plugs and very sensitive to the needle
    setting.
    
    Charlie
    

    RE:.6
    
    Charlie what kind of pipe and plug do you use? He is using, I believe,
    a Davis pipe with K&B plug, no idle bar. 
    
    Dennis
    

    I use a Hatori pipe and a K&B RC Long plug with Idle Bar.  Plug life is
    good unless you run the engine lean then it eats the plug in 1 flight.
    I run an 11/7 prop and I don't know that the pipe length is.
    
    Charlie
    

    
    Referring to reply 1555.8.  Charlie, doesn't a YS 45 use a standard
    length glow plug?  My rear port YS runs on standard length plugs.   I
    do not have any problems (carbon) either in the engine or pipe, but I
    am curious about the glow plug length.  I haven't even disassembled 
    mine in three years of running on an Ultra Sport 40.  I run McCoy D 8
    plugs (same as idle bar heat range without idle bar) and an APC 10x9
    prop which equals impressive vertical.  Pipe and header are both by
    MACS.
    
    Ron Mouser

    Ron,
    	I've always used an RC Long in my YS.  Even the small OS engines
    like the 25FP use a long plug.  I don't think I even own an engine that
    uses a short.  I think that the Idle Bar is probably optional for most
    modern engines.  What kind of fuel do your run?  I run Red Max 12%.
    I never tried a high pitch prop but my UNIC would go straight up with
    the 11/7.  I have since removed the pipe and am running it with a
    standard muffler because I was not real happy with the throttle
    response with the pipe.
    
    Charlie
    

    
    Charlie,
    
    I run Morgan Cool Power 15% nitro.  The 15% helps at this altitude.  
    Albuquerque is a mile high at the center of the city.  I thought that
    long reach plugs might cause detonation problems due to the threads
    extending into the combustion chamber.  Like I said, I have never had
    it apart, so I have not seen the plug in the head with the head off.
    
    The engine does fine on synthetic only.  The gunk on the plane is
    always green like the fuel.  I am VERY fussy about carb settings.
    Is your YS side or rear port?  Mine is rear port, so I have to use a
    pipe, which I want anyway.
    
    I still don't understand the carbon problem.  I talked to other YS
    owners and they have no carbon problems either.
    
    Ron

    I never experienced any detonation problems with my YS on a pipe. 
    Mine's a side exhaust.  I've been using half castor fuel for the extra
    corrosion protection.  I had bearing problems with the YS until I
    realized that raw fuel was getting back into the engine from the pipe
    after I put in after run oil.  The plane is a sholder wing with the
    pipe underneath so the pipe doesn't get removed routinely.  I found out
    that there was quite a bit of fuel in the pipe after a flight.  That's
    one reason I went to the conventional muffler.  I may try the pipe
    again sometime because the performance was awsome.
    
    Charlie
    

    Charlie,
    
    Well, the bottom line is that we have two YS 45's that run great,
    that's the best part!  Corrosion is not a factor here, altitude is.
    Has anyone figured out the carbon problem yet?  I'm very curious about
    that.
    
    Ron

    Carbon has to come from the oil.  I'd change brands in a heartbeat if I
    saw any excess buildup.  Idle may improve with a long reach plug.  The
    short plug puts the element further from the combustion process.  I've
    had good plug life with the K&B plug.  I know a guy that uses the McCoy
    plugs in his OS61 Pattern engines with good results.  I've been using
    the OS#8's in my OS61.  The OS plugs are a ripoff price wise though.
    
    Charlie
      
    
    

    Charlie,
    
    Is your OS 61 the long stroke?  I also have one (rear port) in my other
    Ultra Sport 60.  The main reason I use McCoy plugs is that is what my
    favorite hobby shop carries.  They do carry OS, but he was honest in
    saying they do no better than McCoys.  He said some customers insist 
    on OS.
    
    The Ultra Sports successor is a Bridi Escape which is not built yet.
    That is what the OS 61 is really for.  Boy I love that engine as much
    as the YS.  I think I like your taste in engines! I'll bet you don't
    like FOX.
    
    Ron

    FOX is a three letter word that I hate. Fox's have beaten my engine
    tuning skills before now. 
    
    Charlie and I have almost the same stable of engines with the
    exceptions that he has a gas engine and an OS 120. I have YS120 - no 
    contest there :-)
    
    I also replaced my YS45 with an OS46SF w/pump. Not quite as powerfull
    but very close. Runs much better on the (same header and), pipe, starts 
    better, throttles beautifully. 
    
    I killed my YS45 with much abuse and rpm. Never had a carbon problem
    and I used full castor for three years. Did have carb. gasket and
    fuel/throttling problems. Always forgave it though because of what it
    would do on an 11 x 7.  It always ran better on a std muffler with a
    K&B plug with idle bar.
    
    Night all..........
    
    
    E x E.

    
     E,
    
        The way you ran that YS-45, that LAST thing you needed to worry
    about was CARBON BUILD UP! :)

    You made me smile - thanx!
    

    Ron,
    	You're right - FOX is a three letter word for JUNK.  And THey're
    ugly too.  My OS61 is the Hanno Long Stroke.  It turns 10.2K on 10%
    fuel with a 12-11 APC prop.  I haven't had a chance to play with the
    pipe length since it has been run in so it may do better than that. 
    Right now, most of my engines are OS.  I have a YS45 that I like and I
    will probably eventually own a YS120 4-stroke.  This is definately the
    engine of choice for Pattern!  
    
    Charlie
    

    No answer on the carbon problem. The pilot has decided to change to a
    Mac pipe from a Davis. Fuel doesn't seem to be the problem. Same fuel
    used on eveything else and other pilots use it with no problems. Seems
    to be a combination of variables on that one plane. I'm not really sure
    that he even has the pipe cut to the right length. Will let you know
    if the pipe makes a difference.
    
    Dennis
    

Was the engine stored for some period of time before the carbon was noticed? 
Was 3-in-1 oil or something similar used to "pickle" it? It could be a one 
time application that made the deposits if you only have the one inspection 
to go by.

    Re: .21
    No this was a new engine used only on this plane over this summer. The
    engine is maybe 5 months old.

    Pipe length is critical with a tuned pipe setup.  He may have somehow
    been burning raw fuel in the pipe if he has excess carbon buildup. 
    This could be caused by an incorrect pipe length.  Correct length is a
    function of engine RPM.  It takes experimentation to get it right but
    most of us just throw it on and fly.  (myself included)  Sometimes we
    get lucky other times we're way off on pipe length.  The proper way is
    to use a tach and vary the pipe length from too long to progressively
    shorter until you find maximum RPM.  Then lengthen it slightly.  In hot
    humid weather, you need to increase pipe length up to an inch just to
    compensate for the loss of power and RPM.  I took the pipe off of my
    funfly plane just because I wasn't willing to fool with it.
    
    Charlie
    

    Just to let you know. I taked with the pilot last night and since he
    has changed from a Davis pipe to a Mac he has noticed a big improvement
    in power and RPM. The Mac pipe is much louder than the Davis but seems
    to have less residue build up inside after flying. Only time will tell
    with the carbon build up. I haven't seen this new pipe in action yet
    and I don't have an update a spent plugs with the new pipe. He is still
    running the same fuel...Omaga.
    
    Dennis