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    Love it - 9/5/2003 9:27:00 AM   
    catboater



    Posts: 382
    Joined: 1/7/2002
    From: Bothell, WA, USA
    Status: offline     		Mine have been great!

    (in reply to Kirk RC)
           Post #: 101

    Lets take a poll on the FX 91 - 9/5/2003 11:06:27 AM   
    Flyboy Dave



    Posts: 13511
    Joined: 3/20/2002
    From: San Bernardino County, CA, USA
    Status: offline     		What is the mounting flange size on the .91 carb
    in mm. ?

    Dave.

    _____________________________

    An engineer says.... "That won''t work".
    A mechanic says..."Oh yeah, watch this".
    "Old Age, and Treachery will overcome youth and skill".
    Revver Bro #4.

    (in reply to Kirk RC)
           Post #: 102

    Lets take a poll on the FX 91 - 9/5/2003 4:32:36 PM   
    2thelmt



    Posts: 102
    Joined: 12/28/2001
    From: Acton, ON, CANADA
    Status: offline     		I cut my needle valve off and mounted it to the fire-wall last night. Will see what happens this weekend. Fingers crossed
    Ian

    _____________________________

    "The only way of discovering the limits of the possible is to venture a little way past them … into the impossible.&q

    (in reply to Kirk RC)
           Post #: 103

    Carb throat size - 9/6/2003 12:31:00 AM   
    PilotLight



    Posts: 855
    Joined: 8/15/2003
    From: Benton Harbor, MI, USA
    Status: offline     		Flyboy Dave:

    Tower Hobbies says on the engine parts page it's 15 mm. If you click on the carb parts and check just the carb assembly, it says 14.9 mm. Can't be sure, but the 7L carb does fit nicely. It just mounts differently. If you notice on the 91 carb the throat has extra material for mounting, ie thicker walls.

    http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCA49&P=Z

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    (in reply to Kirk RC)
           Post #: 104

    Well, shoot man....no wonder.... - 9/6/2003 8:53:46 PM   
    Flyboy Dave



    Posts: 13511
    Joined: 3/20/2002
    From: San Bernardino County, CA, USA
    Status: offline     		...I think the main reason the .91fx runs like poop is the
    carb....

    ....it's too small. I see it has a 15mm flange....but only
    a 9.5mm bore. It will never breathe like that.

    I see it uses a nice extended "high volume" muffler, but
    chokes it down with that wimpy carb. As a comparison....
    the OS .60 fsr, and the K&B .61 (both ringed Motors)
    use a 8.5mm bore carb, that is kinda standard.

    I know for a fact (cause I'm a motor-head) the .91fx will
    benefit from a larger carb....especially in tandem with
    the big muffler. The big Magnum carb is 15mm with an
    11mm bore....and they're like only $34.95....

    ....I don't like remote needles anyway....I prefer the precise
    metering of fuel, right at the carb where it needs to be....

    ....not back by the fuel tank.

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    _____________________________

    An engineer says.... "That won''t work".
    A mechanic says..."Oh yeah, watch this".
    "Old Age, and Treachery will overcome youth and skill".
    Revver Bro #4.

    (in reply to Kirk RC)
           Post #: 105

    ....yep, 11mm.... - 9/6/2003 9:11:58 PM   
    Flyboy Dave



    Posts: 13511
    Joined: 3/20/2002
    From: San Bernardino County, CA, USA
    Status: offline     		....I think this carb will make the fx run a whole heck of
    alot better....not to mention the air-leaks, vibration,
    bubbles and all the other stuff....it looks to me that the
    whole shebang on the .91 is junk. :

    I saw on the link that that carb is the "replacement" carb
    from OS for the .91fx....I guess they thought the carb was
    junk too....

    I'll bet a sixer the fx with the Magnum carb, stock muffler,
    running on a good fuel like PowerMaster 15% blend with
    castor, not over-propped....with a 13-8 MAS scimitar....
    (proper comb. of thrust and speed), and a Fox Miracle
    plug....it will run like a top....

    ....any takers ?

    Dave.

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    _____________________________

    An engineer says.... "That won''t work".
    A mechanic says..."Oh yeah, watch this".
    "Old Age, and Treachery will overcome youth and skill".
    Revver Bro #4.

    (in reply to Kirk RC)
           Post #: 106

    Lets take a poll on the FX 91 - 9/7/2003 2:59:23 AM   
    2thelmt



    Posts: 102
    Joined: 12/28/2001
    From: Acton, ON, CANADA
    Status: offline     		Well after 3 FLAWLESS running flights, my 91 FX finally does what it supposed to. I cut the needle valve off, re-mounted, and this engine is like NIGHT & DAY.
    Not a sputter or dead stick, and sounded great-had to fly mostly at 3/4 throttle, this thing really pulls.
    For some this may be "hacking", but if done right, it looks good too.
    Ian

    _____________________________

    "The only way of discovering the limits of the possible is to venture a little way past them … into the impossible.&q

    (in reply to Kirk RC)
           Post #: 107

    Lets take a poll on the FX 91 - 9/7/2003 3:51:30 AM   
    Hircflyer



    Posts: 769
    Joined: 12/6/2001
    From: Kailua, HI, USA
    Status: offline     		Whooooooo, Whoooooo, yipeeee, !!!!!!
    Perry Pump fixed my OS .91Fx......

    Finally after fuel line changes, needle valve O ring changes, remote needle valve installation, TODAY engine ran the whole tank through without leaning out, sagging and going dead stick. And you could touch the cylinder after landing without frying your finger prints.

    PERRY PUMP is the answer!!!!!

    13x8 prop 10% Powermaster caster Blend fuel.

    Amazing! OS needs to sell this engine with pump attached to the rear of crankcase......anyone think they ever will ?

    I don't !

    _____________________________

    Finally! Everyday is a weekend

    (in reply to Kirk RC)
           Post #: 108

    Lets take a poll on the FX 91 - 9/7/2003 5:47:14 AM   
    2thelmt



    Posts: 102
    Joined: 12/28/2001
    From: Acton, ON, CANADA
    Status: offline     		Why spend $$$ on a pump when you don't have to?

    _____________________________

    "The only way of discovering the limits of the possible is to venture a little way past them … into the impossible.&q

    (in reply to Kirk RC)
           Post #: 109

    RE: Lets take a poll on the FX 91 - 9/8/2003 1:39:14 PM   
    Blackie



    Posts: 1896
    Joined: 2/10/2002
    From: Austin, TX, USA
    Status: offline     		Cut and paste from old RCU.

    Blackie

    PilotLight
    New Friend

    Offline
    Registered: Aug 2003
    Location: Benton Harbor, MI
    Discussion Post Total: 10

    New Post
    (post # 110)

    Mine runs great too! Mounted needle valve, which broke off, behind motor and now it runs great. No bubbles in fuel line. Starts right up, idles slow, full throttle really pulls. Not a hint of hesitation from idle to full throttle.





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    09-07-2003 3:59 AM




    Hircflyer
    Retired and loving it

    Offline
    Registered: Dec 2001
    Location: Kailua HI
    Discussion Post Total: 301

    New Post
    (post # 111)

    I had tried everything else including moving the needle valve to the firewall. With the same results......deadstick.

    But the pump fixed it.


    __________________
    FINALLY.....everyday is a weekend





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    09-07-2003 6:56 AM




    Blackie
    Senior Member

    Offline
    Registered: Feb 2002
    Location: Austin TX
    Discussion Post Total: 1475

    New Post
    (post # 112)

    Hiricflyer, I viewed what things you tried doing but didn't notice whether you tried changed out the muffler or not?

    The muffler plays a big part in the fix as well. As I mentioned earlier in my previous post referring to the 91FX, running on my SS60 (STICK) I had to swap out the muffler to one off of a Magnum, and solved the problems, once I went to a Pitts is when the leaning started again.

    I am not going to pump this engine, I am going to stand my ground. If I continue to keep getting the leaning. I will just continue to send this engine back to HS.

    Blackie





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    09-07-2003 4:45 PM




    Hircflyer
    Retired and loving it

    Offline
    Registered: Dec 2001
    Location: Kailua HI
    Discussion Post Total: 301

    New Post
    (post # 113)

    No, always kept the stock muffler that came with the engine......main reason muffler fit the tunnel that the PT-19 has for the muffler.

    I tried everything to keep from putting a pump on.....yesterday however was the day.....if the pump didn't fix the engine I was going to take it off the airplane and throw it in the swamp. I was going to get a 4 stroke 1.20 for it. While I was fueling the airplane I told it so.

    I must have scared the the motor because it ran fine........first time in many attempts.

    The PUMP did it!

    Go figure.


    __________________
    FINALLY.....everyday is a weekend





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    09-07-2003 8:52 PM




    PilotLight
    New Friend

    Offline
    Registered: Aug 2003
    Location: Benton Harbor, MI
    Discussion Post Total: 10

    New Post
    Possible solutions (post # 114)

    Duing my attempts to get the engine to run on a test stand I had a hard time keeping the engine running. My dad didn't have the muffler plumbed to the tank and the engine would only start and run for about 2 seconds. He thought it was leaning out so he tried to richen the mixture. I found the tubing off the muffler and that fixed the leaning out once it was connected.

    This motor needs positive fuel flow to keep it running. It won't draw fuel thats not pressurized. My UCD3D has a fuel tank mounted above the carb by about 1 inch, and before the High Speed needle valve was mounted to the firewall behind the engine, the fuel used to drip out the carb before it was started.





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    09-08-2003 1:35 AM




    2thelmt
    Spader

    Offline
    Registered: Dec 2001
    Location: Acton ON Canada
    Discussion Post Total: 48

    New Post
    (post # 115)


    quote:
    --------------------------------------------------------------------------------
    Originally posted by Blackie
    Hiricflyer, I viewed what things you tried doing but didn't notice whether you tried changed out the muffler or not?

    The muffler plays a big part in the fix as well. As I mentioned earlier in my previous post referring to the 91FX, running on my SS60 (STICK) I had to swap out the muffler to one off of a Magnum, and solved the problems, once I went to a Pitts is when the leaning started again.

    I am not going to pump this engine, I am going to stand my ground. If I continue to keep getting the leaning. I will just continue to send this engine back to HS.

    Blackie
    --------------------------------------------------------------------------------



    When i changed my muffler I also noticed an improvement. Originally I used a .61 sized pitts muffler and one of my first attempts at solving the problems was to switch to a B.C.M .91 pitts.
    Good for you to stand your ground! I wish I had the time, but i don't, so I hacked mine till she worked.
    I also use large diameter tubing with drilled out clunks.
    3 more SOLID flights today. Thats 6 in a row now...I think.

    Stump puller when she runs right! 2\3 trottle most of my flying with awsome bursts of full. My 9.6 Lb Staudacher will go unlimited vert with this plant-Love it now.
    Ian


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    Signature... Wheres my pen?





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    09-08-2003 2:30 AM




    OldRookie
    Senior Member

    Offline
    Registered: Dec 2001
    Location: Minnesota
    Discussion Post Total: 187

    New Post
    (post # 116)

    I have about 25 flights on my 91FX in a Delta Vortex. It ran well with an UltraThrust muffler, and not as well with the stock muffler.
    The only problem I had was with the idle. Before takeoff it idled fairly fast, but after a few minutes if the throttle was brought back to idle it would kill out.
    The last three flights the engine started to go lean on long up lines. I may have to go to a pump also. It always seemed as if it were not running exactly right.
    HircFlyer, which pump did you use to get yours going?

    Greg





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    09-08-2003 6:02 AM




    Hircflyer
    Retired and loving it

    Offline
    Registered: Dec 2001
    Location: Kailua HI
    Discussion Post Total: 301

    New Post
    (post # 117)

    Perry P-30 at your LHS or Tower for 29.95.

    Worked for me.

    Blackie I hope they're paying the postage.


    __________________
    FINALLY.....everyday is a weekend





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    09-08-2003 6:05 AM




    Flyboy Dave
    Moderator

    Offline
    Registered: Mar 2002
    Location: So. Cal.
    Discussion Post Total: 1996

    New Post
    Blackie.... (post # 118)

    ....aren't the mufflers pretty much the same on the fx,
    and the xls....lenght, diameter....volume....?

    ....with the added extension in the middle...?

    Dave.


    __________________
    "Good Flying"......Flyboy Dave.
    Revvers Brotherhood Member #4
    "Old Age, and Treachery.........
    Will Overcome Youth And Skill."
    _________________________





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    09-08-2003 6:06 AM




    Flyboy Dave
    Moderator

    Offline
    Registered: Mar 2002
    Location: So. Cal.
    Discussion Post Total: 1996

    New Post
    Hircflyer.... (post # 119)

    ....is the Perry p-30 the occillating, or "vibrating" pump ?


    __________________
    "Good Flying"......Flyboy Dave.
    Revvers Brotherhood Member #4
    "Old Age, and Treachery.........
    Will Overcome Youth And Skill."

    (in reply to 2thelmt)
           Post #: 110

    RE: Lets take a poll on the FX 91 - 9/8/2003 1:44:57 PM   
    SMALLFLY-



    Posts: 2151
    Joined: 12/9/2001
    From: Evansville, IN, USA
    Status: offline     		My OS 91fx started giving me bubbles in the line so I ordered a GMS 120 remote needle valve complete assbly from tower for 11.99 I tried it yesterday and it worked great. I only ran it for 4-5 minutes on a test stand but NO bubbles in the line and it's cheap.

    (in reply to Blackie)
           Post #: 111

    RE: Lets take a poll on the FX 91 - 9/8/2003 1:48:43 PM   
    Blackie



    Posts: 1896
    Joined: 2/10/2002
    From: Austin, TX, USA
    Status: offline     		Flyboy Dave, to answer you question concerning the muffler. The Mag is a bit larger in diam, I never thought about removing the spacer on the OS.

    Had a slight mishap in my muffler theory, ran the engine again this weekend but on my WM SS60 (large stick) and was having the same problems with the leaning. I went back to the previous setup that I used before I moved the engine to the Shoestring but was unable to get the engine to perform as it did when I had it on the SS60, in other words its still leaning.

    I absolutely refuse to give into a pump until I have wore out my welcome with OS, I just received the engine back from warranty repair but they only replaced damaged parts caused from the leaning, they did not fix the problem it self. I plan on contacting OS via phone today as they refuse to answer my email sent in over a week ago.

    The Perry p-30 is the 0ccillating pump.

    Blackie


    Blackie

    (in reply to Blackie)
           Post #: 112

    RE: Lets take a poll on the FX 91 - 9/8/2003 6:49:08 PM   
    Hircflyer



    Posts: 769
    Joined: 12/6/2001
    From: Kailua, HI, USA
    Status: offline     		Blackie! Good Luck with OS Please let us know what happens......

    Bax is so upset with my posts in that forum, he just deletes my posts......but thats okay mines fixed!

    (in reply to PilotLight)
           Post #: 113

    RE: Lets take a poll on the FX 91 - 9/8/2003 6:54:31 PM   
    SVFlier



    Posts: 168
    Joined: 3/24/2003
    From: Scottsdale, AZ, USA
    Status: offline     		I love my 91fx! The only problem I have with it is that it is a bit weak when it comes to surviving vertical high-speed