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Author Topic: Another vintage project from Great Britain, target Speed Week 2011  (Read 70813 times)
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octane
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« Reply #15 on: October 13, 2010, 05:47:29 AM »

Methanol tap, has to close automatically if I fall and control from the handlebars... Tall order, drawn a few designs, it got simpler and simpler as it went!!! The basis is a S/S Swagelok 3/8th valve

Result:







Spring return, cable operated from a twin cable throttle mounted on the left hand side clip-on. The cable will pass through it and the lanyard underneath to hold it open. I also plan to put a micro switch on the back of the tap to kill the ignition when the valve closes.

See you all,

Patrick
 

Patrick, I don't want to put down your brilliant tap !!!
On the contrary; it's a extraordinarily well made nifty little contraption

BUT

I tried , or rather the guy who helped me in the beginning of my build,
tried to make something similar



...with internals based on an existing tap, just like you did



...but it never got to work well.....er....at all




What the rules actually says it that
1)...you need a positive off kill switch to stop a running machine,
operated without removing hands from handlebar

2)...you must have a tether-type / lanyard kill switch

3)...running 'fuel' ; you must have a fuel shut-off
operated without removing hands from handlebar

...so instead of investing in a 60 tap, do a lot of machining, run cables
and buy, and install, a, twin cable throttle  AND a micro-switch
AND buy, and install, a handle-bar mounted switch for the ignition

the whole thing can be solved with a 44.24
12 volt fuel solenoid-valve from HERE




and a switch on the handle-bar that kills engine AND fuel in one go,
like I ended up doing



( + the lanyard thingy that you're gonna need under all circumstances  )

Tech. inspected at both Speed Week and BUB.
« Last Edit: October 13, 2010, 05:50:57 AM by octane » Logged

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« Reply #16 on: October 13, 2010, 08:00:54 AM »

Hi Lars,

Yes, I've got the lanyard at the end, on the throttle. I did not mod the valve at all, just added the alloy bit for the spring and cable> I've tested it before hand in the vice, smooth closing in about 1/2 second. I querried my idea with Tom, he says it should be OK (once examined!!!) I'll query him again to see if lanyard is enough. I also will have another kill switch on the clip-ons just in case...

And no easy solenoid shut off system cause there's no battery on the bike!!!

Patrick
« Last Edit: October 13, 2010, 08:03:36 AM by thefrenchowl » Logged

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Graham in Aus
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« Reply #17 on: October 13, 2010, 09:17:08 AM »


Graham, yes, that's me, small world indeed... Richard's still there and doing allright. He's not racing much these days, but mostly acts as pit crew for his sons' racing karts!!!

Patrick

Aaah I was right!  grin Don't want to clog up your build thread, but, it's good to know my memory's OK (just!)
I visited Richard last year and stayed a few days, went Karting with the boys too!

Good luck with your build!

Graham
« Last Edit: October 13, 2010, 09:18:47 AM by Graham in Aus » Logged
octane
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« Reply #18 on: October 13, 2010, 10:29:30 AM »

Hi Lars,

Yes, I've got the lanyard at the end, on the throttle. I did not mod the valve at all, just added the alloy bit for the spring and cable> I've tested it before hand in the vice, smooth closing in about 1/2 second. I querried my idea with Tom, he says it should be OK (once examined!!!) I'll query him again to see if lanyard is enough. I also will have another kill switch on the clip-ons just in case...

And no easy solenoid shut off system cause there's no battery on the bike!!!

Patrick

Ahhh! Got ya' now, Patrick !

Sorry for my inappropriate smarty pants display ,
and again: let me express my admiration for you clever fuel tap-design !!!
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« Reply #19 on: October 13, 2010, 12:33:48 PM »

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Lars: let me express my admiration for you clever fuel tap-design

Well, thanks, but that end thingy was the 4th and last design... I started with another valve and tryed to morph into it some levers from H-D Keihin carbs, awful!!!

These are close shots of the rear struts, H section and full of holes, in hardened aluminum, don't know what they call it in the States, Duraluminium over here...



Patrick
« Last Edit: October 13, 2010, 12:38:56 PM by thefrenchowl » Logged

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« Reply #20 on: October 13, 2010, 02:19:21 PM »

it's not so good on a Vee twin due to not enough pulses per engine rev... I'm planning to run mine way faster than the engine, so more pulses per rev and smaller "plenum" volume

There are 2 cycles that should not overlap:
1. is the release of trapped volume between the lobes and the case wall, which is never really constant even with high helix (partially because most discharge is from 1 end, not symmetrically); speeding it up has to help.
2. is the V firing order, with a very long period of both intake valves closed, which backs up pressure between the blower exhaust and the engine. It overloads the blower, and may pop off a valve. AFAIK, nothing but a plenum will cure this, but this volume includes every part of the intervening space including the ports, manifold, etc. A L4 or L6 still needs buffer volume since the interval between intake cycles is still large, but it's generally contained in the existing plumbing and doesn't need an add-on.
It's been suggested that a V engine needs at least 2 displacement for a buffer; I'm not sure this much is really needed.
There's also a big diff between blow-through and draw-through as to plenum design.
A draw-through is wet, which means that any violent cross-sectional expansion will cause fuel drop-out. The entire tract should be slightly downhill the whole way, and the largest X-section as small as possible: 3" OD 12" long is preferred to 4" 7" (length will compromise response, but keep the fuel suspended).
A blow-through doesn't have these problems, and can use a short (3"?) but big disc- or torus-shaped OD (6"?) plenum as storage as long as the entry-exits are smooth, large radius transitions.
I suspect (but no proof) that the entry and exit tubes can approach each other inside the plenum to a distance as close as 625% of their area (2" entry is 3.125" away from the 2" exit, etc.) without penalty if the exit's radius is well shaped.
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« Reply #21 on: October 13, 2010, 02:22:18 PM »

Hiya Patrick, good to see you on here.
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« Reply #22 on: October 13, 2010, 02:33:34 PM »

Just rambling: assuming the AMR500, I'm not sure how the rotor coating or the seals like methanol.
Some excellent pioneer work has been done on using the Keihin CV carbs as blow-through.
Where is the drive from? I'm running a #40 sprocket around the OD of my big twin clutch drum, somewhere in the low 50s, to drive the Eaton M45 at about 3 clutch speed. This is only 2 engine speed due to the primary ratio.
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« Reply #23 on: October 13, 2010, 04:22:03 PM »


Spring return, cable operated from a twin cable throttle mounted on the left hand side clip-on. The cable will pass through it and the lanyard underneath to hold it open. I also plan to put a micro switch on the back of the tap to kill the ignition when the valve closes.


I would have thought having an extra control that you have your hand on might make things a bit busy, especially if it gets bumpy
There's a guy who runs a Velo in Aus who uses a handlebar mounted choke lever to turn his off. Worked well in Tech, and looked simple.
Very nice tap by the way
G
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« Reply #24 on: October 13, 2010, 06:33:23 PM »

Thanks, Jeff,

It'll be a draw through, methanol in the supercharger should cool it enough!!! Carb is a 1"7/8 S&S MGAL that I moded years ago for methanol, so already set up jet wise, albeit for sea level. It's got 2 main jets, one fixed and a needle one for fast ajustments. I haven't used it for a while, seem to remember it's OK at WOT but seemed to bog a bit in the mid range, I might have been too enthusiastic with enlarging the transitions holes, but easily remedied if needed.

I was looking at a 2" pipe off the blower, that would give me about 700cc as plenum volume. Could increase that a bit to get around 1000cc...

Drive will be off the mainshaft, around 2 to 1 to give 10psi boost. 2.5 to 1 to get 16psi but the supercharger starts to spin a lot!!! The blurb says these AMR 500 can spin for a short while at 16000rpm but no mention as what is actually a short while  grin  grin  grin. That's calcs without pumping losses, don't know how much losses I should account for... 5%? 10%?

One can also infer from the blurb that they are really designed for injected EPAed motors, they don't get the vaporisation coolling effect, so they would get very hot then. With dead cool methanol in it, 16000 rpm might be quite safe??

Back to the throttle: I won't have to hold it open, the lanyard thingy goes underneath it:




Patrick
« Last Edit: October 13, 2010, 06:38:45 PM by thefrenchowl » Logged

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« Reply #25 on: October 13, 2010, 08:40:22 PM »

I think you're right - the time is limited to temperature, and alcohol should help a lot.
Goes into an extension of the original manifold, or?
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« Reply #26 on: October 14, 2010, 12:49:27 AM »

Patrick, the system Lars is showing is relatively safe. There is a single fuel line running through a sealed system and the electrical currents in the system are low amperage.  Power for a small item like this can easily be provided by a little sealed battery hidden somewhere on the bike.

Several times in my life I have stopped runaway engines with a kill button or switch.  This is not uncommon on Amal equipped bikes.  The throttle slides will occasionally stick in the wide open position.  It was not unusual for the insulation on the wire to the kill switch to blister from the heat.  This happened on a Yamaha SC500, too.  It is the large amount of current that is going to the kill switch that is causing the heat.

Harley magnetos are something I am not familiar with and I cannot give good advice.  It is worth checking, though, to verify that the kill switch part of this fuel shutoff arrangement will handle the current without overheating.  A sensitive part of our anatomy is in close proximity to these shutoff valves.  A person cannot be too careful.

This looks like a fun build.     

 
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« Reply #27 on: October 17, 2010, 06:10:36 AM »

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wobblywalrus: It is worth checking, though, to verify that the kill switch part of this fuel shutoff arrangement will handle the current without overheating

Hi, there no current or heat generated in the kill switch when it's open on a mag. When closed, it prevents the mag generating the small voltage on the primary coil by shortening the points to earth, so no current/heat either. I basically don't want a battery on the bike  grin

Quote
Panic: Goes into an extension of the original manifold, or?

Will probably have to mod the std manifold, shock horror  grin... A friend has plenty of S/S tubing from his factory, big diameter and thin wall for food stuff hygienic filling lines, should have the bits I need, including tapers/cones reducers to join the big tubes to the manifold...

More bits for the puzzle...Collected the iddler gear that will drive the front mounted magneto. It's actually the 1/2 speed gear on an old XL grind cam 2 I'll never use, rear inlet, its inners bored out and a alloy suitable insert machined for two of 9mm x 24mm x 7mm ball bearings that will roll on the iddler shaft that still needs making... These are the same ball bearings that the KR cams run on...



Patrick
« Last Edit: October 17, 2010, 06:23:48 AM by thefrenchowl » Logged

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« Reply #28 on: October 17, 2010, 10:42:42 AM »

probably have to mod the std manifold

I suspect (haven't cut one up yet) that an Evo manifold might be a good donor. The V separation angle is wrong, but it appears easier to fix than trying to add volume and improve internal shape in a K (which is after all a 1940 part number).
The slight downdraft is actually helpful - invert it, and it assists the rise from the port CL to the valve seat.
As a first step, which Evo engine has an intake port size closest to the K (1.56?). The S&S for that will have a relatively huge throat for the 1-7/8 E etc.
This will also make the transition from your transfer tube easier.
If you don't have the room for a really big radius from the tube to the manifold inlet (like 2") so as not to centrifuge fuel to the outside, the next best shape is supposed to be a torus, but I'm afraid that the entry point and geometry may be fairly picky as to droplet fall-out.
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« Reply #29 on: October 17, 2010, 12:22:26 PM »

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Jeff: I suspect that an Evo manifold might be a good donor

Hum, anything alloy is bad for me cause our works tig welders only do steel (as they are only DC?)

If it was to work and invert it, then it falls deeper into the Vee, restricting the max diameter of the plenum...

I roughly drawn this, not quite to scale, the 3" diameter plenum ending as near as possible to the manifold, that is  if there's enough space between the cyls!!! Plenum and manifold in the same axis:





I suppose I could lift up the plenum a bit by having its floor in line with the manifold floor, that should limit the fuel puddles...

Patrick
« Last Edit: October 17, 2010, 12:28:10 PM by thefrenchowl » Logged

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