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Re: [Small4-strokeEngines] Re: Hoses for inlets on any V-Twin

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  • dagwodzz@bellsouth.net
    They will vibrate even more with rubber mounts. ... From: Kev A Date: 2/25/2013 3:23:54 PM To: Small4-strokeEngines@yahoogroups.com Subject:
    Message 1 of 19 , Feb 25 3:25 PM
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      They will vibrate even more with rubber mounts.   
       
       
       
       
      -------Original Message-------
       
      From: Kev A
      Date: 2/25/2013 3:23:54 PM
      Subject: [Small4-strokeEngines] Re: Hoses for inlets on any V-Twin
       
       

      Wonder why Rotax and Robin etc. fit rubber carb mounts to kill vibes getting to the float needle assembly and messing up the mixture, and Briggs/Kohler/Generac don't?

      A normal installation would see any of these bolted to something heavy iron and not too fussy about fuel burn, but as we hang ours on relatively flimsy lightweight structures, the V-Twin will vibrate much more.

      Maybe that Czech feller had a point, and longer rubber hoses to a remote mounted carb are beneficial? Probably less chance of an in-flight fire too.

      Cheers

      Kev

      --- In Small4-strokeEngines@yahoogroups.com, woody king wrote:
      >
      > Excellent thought, Charlie. I did look but didn't notice any collapse, and they were very stiff new thick hoses. BUT, you are so right. Except the major vaccum would be at idle, and my rpm/power loss was at full throttle. There the vaccum would be very low, but I did not consider the possibility you pointed out. Alot going on. Thanks for the input, I will add that to my "book" of things to remember.  Woody
      >
      > --- On Mon, 2/18/13, RV7Charlie wrote:
      >
      >
      > From: RV7Charlie
      > Subject: Re: [Small4-strokeEngines] Hoses for inlets on any V-Twin
      > To: "Small4-strokeEngines@yahoogroups.com" Small4-strokeEngines@yahoogroups.com>
      > Date: Monday, February 18, 2013, 11:40 AM
      >
      >
      >
      >  
      >
      >
      >
      >
      > Could you see the hoses while running? Manifold vacuum has the potential to collapse a rubber hose, if it isn't designed to handle vacuum (like the spring in a radiator hose).
      >
      > Sent from my iPhone
      >
      > On Feb 18, 2013, at 8:59 AM, woody king wrote:
      >
      >
      >
      >  
      >
      >
      >
      >
      >
      > My experience, that I can't explain, was loss of power using hoses for intake runs. I was using straight 2.25 ID hose which was a great fit onto carb and intake, not restricting at all. Yet, I lost darn near 1000 rpm static. Hoses were about 14" long, with a long sweeping 20 degree overall turn. I went back and my power came back. I would not have thought this would make that much difference. I have used shorter similiar adapters on many things like motorcycles and hovercraft, and they seemed to work fine.     Woody
      >
      > --- On Mon, 2/18/13, Kev A wrote:
      >
      >
      > From: Kev A
      > Subject: [Small4-strokeEngines] Hoses for inlets on any V-Twin
      > To: Small4-strokeEngines@yahoogroups.com
      > Date: Monday, February 18, 2013, 9:29 AM
      >
      >
      >
      >  
      >
      > Juraj Tinka, a czech sport pilot was exchanging useful info with Arif, in Far East Asia, on his V-Twin mounted in a little sports fixed wing aircraft; Arif kindly copied me in.
      >
      > This was a Vanguard B&S but one idea he had that applies to any engine is in one of the emails:-
      >
      > "Carb is standard and mounted on the motor mount.
      > Float type carbs are sensitive for vibrations. This system reduces
      > vibrations from motor."
      >
      > What Juraj showed in the photos was two steel 'U' bend tubes on the heads, running back into long rubber auto hoses to a carburator fitted to the bulkhead.
      >
      > His rig was prop mounted flywheel side, I guess if prop mounted PTO side (on a redrive or taper shaft) on a tractor rig the inlet tubes would be easy, running straight back off the heads into a flange on a carb 12-18" behind the motor. Heat would need watching as the head heat might cook the rubber tubes.
      >
      > What do you guys think? Fairly easy to do by rigging a pair of adapter nbends off the top of the stock manifold, longer inlet tracts might give better power too?
      >
      > Kev
      >

       
    • John
      Long inlet pipes might actually be beneficial if they could be tuned like an exhaust is tuned. If I were to try this, I would certainly use thin wall metal
      Message 2 of 19 , Feb 27 3:57 PM
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        Long inlet pipes might actually be beneficial if they could be tuned like an exhaust is tuned. If I were to try this, I would certainly use thin wall metal tubes mounted reasonably firmly and use short rubber couplers to allow the vibration induced movement. It might take several "joints", each bending in an appropriate direction to allow all the necessary degrees of movement.

        John

        --- In Small4-strokeEngines@yahoogroups.com, "Kev A" <kevin@...> wrote:
        >
        > Wonder why Rotax and Robin etc. fit rubber carb mounts to kill vibes getting to the float needle assembly and messing up the mixture, and Briggs/Kohler/Generac don't?
        >
        > A normal installation would see any of these bolted to something heavy iron and not too fussy about fuel burn, but as we hang ours on relatively flimsy lightweight structures, the V-Twin will vibrate much more.
        >
        > Maybe that Czech feller had a point, and longer rubber hoses to a remote mounted carb are beneficial? Probably less chance of an in-flight fire too.
        >
        > Cheers
        >
        > Kev
        >
        > --- In Small4-strokeEngines@yahoogroups.com, woody king <woodyking2001@> wrote:
        > >
        > > Excellent thought, Charlie. I did look but didn't notice any collapse, and they were very stiff new thick hoses. BUT, you are so right. Except the major vaccum would be at idle, and my rpm/power loss was at full throttle. There the vaccum would be very low, but I did not consider the possibility you pointed out. Alot going on. Thanks for the input, I will add that to my "book" of things to remember.  Woody
        > >
        > > --- On Mon, 2/18/13, RV7Charlie <mcsophie@> wrote:
        > >
        > >
        > > From: RV7Charlie <mcsophie@>
        > > Subject: Re: [Small4-strokeEngines] Hoses for inlets on any V-Twin
        > > To: "Small4-strokeEngines@yahoogroups.com" <Small4-strokeEngines@yahoogroups.com>
        > > Date: Monday, February 18, 2013, 11:40 AM
        > >
        > >
        > >
        > >  
        > >
        > >
        > >
        > >
        > > Could you see the hoses while running? Manifold vacuum has the potential to collapse a rubber hose, if it isn't designed to handle vacuum (like the spring in a radiator hose).
        > >
        > > Sent from my iPhone
        > >
        > > On Feb 18, 2013, at 8:59 AM, woody king <woodyking2001@> wrote:
        > >
        > >
        > >
        > >  
        > >
        > >
        > >
        > >
        > >
        > > My experience, that I can't explain, was loss of power using hoses for intake runs. I was using straight 2.25 ID hose which was a great fit onto carb and intake, not restricting at all. Yet, I lost darn near 1000 rpm static. Hoses were about 14" long, with a long sweeping 20 degree overall turn. I went back and my power came back. I would not have thought this would make that much difference. I have used shorter similiar adapters on many things like motorcycles and hovercraft, and they seemed to work fine.     Woody
        > >
        > > --- On Mon, 2/18/13, Kev A <kevin@> wrote:
        > >
        > >
        > > From: Kev A <kevin@>
        > > Subject: [Small4-strokeEngines] Hoses for inlets on any V-Twin
        > > To: Small4-strokeEngines@yahoogroups.com
        > > Date: Monday, February 18, 2013, 9:29 AM
        > >
        > >
        > >
        > >  
        > >
        > > Juraj Tinka, a czech sport pilot was exchanging useful info with Arif, in Far East Asia, on his V-Twin mounted in a little sports fixed wing aircraft; Arif kindly copied me in.
        > >
        > > This was a Vanguard B&S but one idea he had that applies to any engine is in one of the emails:-
        > >
        > > "Carb is standard and mounted on the motor mount.
        > > Float type carbs are sensitive for vibrations. This system reduces
        > > vibrations from motor."
        > >
        > > What Juraj showed in the photos was two steel 'U' bend tubes on the heads, running back into long rubber auto hoses to a carburator fitted to the bulkhead.
        > >
        > > His rig was prop mounted flywheel side, I guess if prop mounted PTO side (on a redrive or taper shaft) on a tractor rig the inlet tubes would be easy, running straight back off the heads into a flange on a carb 12-18" behind the motor. Heat would need watching as the head heat might cook the rubber tubes.
        > >
        > > What do you guys think? Fairly easy to do by rigging a pair of adapter nbends off the top of the stock manifold, longer inlet tracts might give better power too?
        > >
        > > Kev
        > >
        >
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