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880cc 12 Valve? #738001
06/07/18 10:47 pm
06/07/18 10:47 pm
Joined: Jan 2004
Posts: 3,700
ca, us
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DMadigan Offline OP
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A long time ago I had drawn a head and cylinder for an 880cc 12 valve. I never found a way to get it cast but today there are 3D wax printers that can do it without having to make a mold. More expensive for casting each part but saving the mold cost over the limited number of parts wanted would justify it.
[Linked Image]
[Linked Image]
[Linked Image]
The pushrod tubes are integral with the cylinder and the rockerboxes are integral with the head. Uses H*nda valves and pistons, stock rods can be bushed for the smaller wrist pins. 72 x 72mm bore and stroke. Valves operated Rickman style with the pushrods outboard of the rocker shafts. Coarse adjustment by screw on the pushrod and shim under lash caps to trim between valves. Outer four studs go down into the case.

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Re: 880cc 12 Valve? [Re: DMadigan] #738006
06/07/18 11:08 pm
06/07/18 11:08 pm
Joined: Oct 2012
Posts: 3,642
Running from demons in WNY
Hillbilly bike Offline
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The small combustion chamber looks good... How does the wax process work when pouring molten metal?


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 880cc 12 Valve? [Re: DMadigan] #738009
06/07/18 11:20 pm
06/07/18 11:20 pm
Joined: Sep 2001
Posts: 431
Great Southern Land
tridentt150v Offline
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Great Southern Land
I thought you make the wax model, then make the actual casting mold over it, then heat and melt the wax to remove it leaving the hollow casting, then pour in the molten metal, but I was researching belt buckles when I was looking at how it worked smile

Re: 880cc 12 Valve? [Re: DMadigan] #738011
06/07/18 11:52 pm
06/07/18 11:52 pm
Joined: Feb 2015
Posts: 275
Melbourne Oz
S
Steven A Offline
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Steven A  Offline
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Melbourne Oz
Superb! Lots of work in that.

My employer used prototyping services that might move this along. Can you import the CAD files in to OnShape .com. Then the design can be reviewed and the project could get a shove along.

Re: 880cc 12 Valve? [Re: DMadigan] #738065
06/08/18 4:41 pm
06/08/18 4:41 pm
Joined: Nov 2009
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bon Offline
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If you have gone that far, why not go a bit further, and make it overhead cams ? Must be a way to drive them from the timing chest ? Give Allan Millyard a shout, i am sure he would have ideas about it !

Re: 880cc 12 Valve? [Re: DMadigan] #738167
06/09/18 5:13 pm
06/09/18 5:13 pm
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DMadigan Offline OP
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There is not a lot to gain with a DOHC. NASHCAR pushrod engines already turn 10,000 RPM.
http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm
I already looked at a couple of ways to drive a DOHC. Use a belt from one of the cams or a timing chain directly from the crank. Both require surgery, the chain more so because the engine case and cover have to be opened and modified to bolt on the chain box besides shaving off the cylinder and head fins. The belt would need a cover and would stick out quit a bit. A middle pulley would be needed to stabilize the long runs up to the cam box which means a stiffer cover than just sheet metal.
The roller chain primary would be another limiting factor. Rollers produce a chordal motion as each roller contacts the sprocket and is lifted over the top.

Re: 880cc 12 Valve? [Re: DMadigan] #738239
06/10/18 11:50 am
06/10/18 11:50 am
Joined: Oct 2012
Posts: 3,642
Running from demons in WNY
Hillbilly bike Offline
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Since the Trident is a pushrod engine, keeping the pushrods would not be negative feature and certainly make the head more of a bolt on than a major modification.. I believe the only reason to have a 4 valve head is for a shallow fast burn combustion chamber with high velocity intake ports so a higher compression ratio can be used with modern pump fuel..Combined with cams designed for the head, you could expect a noticeable increase in power overall...Head, cams, intake, and maybe carbs would be a price not for the feign of heart...


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 880cc 12 Valve? [Re: DMadigan] #738345
06/11/18 9:24 am
06/11/18 9:24 am
Joined: Feb 2015
Posts: 275
Melbourne Oz
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Steven A Offline
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Originally Posted by DMadigan
There is not a lot to gain with a DOHC. NASHCAR pushrod engines already turn 10,000 RPM.
http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm


This is highly pertinent. However the comparison to NASCAR might lead us to prefer a modern six valve head???

Re: 880cc 12 Valve? [Re: DMadigan] #738356
06/11/18 11:34 am
06/11/18 11:34 am
Joined: Jan 2005
Posts: 1,662
East Bethany New York
Dick Harris Offline
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Thanks DM, lots of interesting info to try to understand. Dick

Re: 880cc 12 Valve? [Re: Steven A] #738358
06/11/18 11:47 am
06/11/18 11:47 am
Joined: Sep 2001
Posts: 431
Great Southern Land
tridentt150v Offline
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Great Southern Land
Originally Posted by Steven A
Originally Posted by DMadigan
There is not a lot to gain with a DOHC. NASHCAR pushrod engines already turn 10,000 RPM.
http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm


This is highly pertinent. However the comparison to NASCAR might lead us to prefer a modern six valve head???

Or maybe we should be trying a polyquad head design?
http://www.motortecmagazine.net/the-future-of-4-valve-engines/

Re: 880cc 12 Valve? [Re: DMadigan] #738373
06/11/18 3:02 pm
06/11/18 3:02 pm
Joined: Jan 2004
Posts: 3,700
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DMadigan Offline OP
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The Polyquad is modifying an existing design to increase swirl in a four valve. There is another way that produces far greater swirl and less cross flow out the exhaust but it takes a completely different approach. They are trying to put patches on dinosaur engines.
The two valve Triumph has very little swirl because the ports and valves are directly opposite each other so any change, even rotating the valves slightly around the cylinder would help.
Another way to eliminate most of the cross flow is to move the intake port above the valve so the flow is down into the cylinder instead of across. A small problem with the fuel tank location and AMAL carburettors do not work well in a downflow position.
Their port runners are longer resulting in oval adapters. A little hard to do on a triple and keep the airbox and oil tank. Fuel injection would go a long way to making more power and better BSFC.
All this is chasing fairies though. An old air cooled triple will never compete with a modern design. We could go with a three valve design with better ports and be a long way ahead. A triple valve triple.
Yamaha built a seven valve head for Toyota but there was little gain over the four valve for the expense. Notice that Yamaha even dropped their five valve design and uses a four.

Re: 880cc 12 Valve? [Re: DMadigan] #738436
06/11/18 11:15 pm
06/11/18 11:15 pm
Joined: Sep 2001
Posts: 431
Great Southern Land
tridentt150v Offline
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Great Southern Land
yeah, the polyquad is just the cheapest and easiest solution to adapt to existing heads. Its much simpler to have a mix of valve and throat sizes, takes minimal engineering.
And the research for polyquad head design wasn't done on dinosaur engines, it was done to address incomplete burn.....power, efficiency and emissions being direct benefits.

Last edited by tridentt150v; 06/11/18 11:18 pm.
Re: 880cc 12 Valve? [Re: DMadigan] #738619
06/13/18 5:12 pm
06/13/18 5:12 pm
Joined: May 2013
Posts: 202
Fl., U.S.A.
Thunderbutt Offline
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Fascinating stuff. Regarding the discussion of cam chain or push rod for valve actuation, I believe it was the Honda CX 500 which used an OHV, four valves per cylinder. Two push rods per cylinder. Each push rod would activate the "Y" shaped rocker arm that opened and closed two valves simultaneously. Two intake or two exhaust. The push rod pressing the lower portion on the "Y" and the upper portion of the "Y" pressing directly on the valve stems. If I recall they also had a 10,000 rpm red line. Not that I would expect a T150 or T160 to turn that high.
Would the be enough room inside the rocker boxes for this type of configuration?

Re: 880cc 12 Valve? [Re: DMadigan] #738637
06/13/18 9:07 pm
06/13/18 9:07 pm
Joined: Oct 2012
Posts: 3,642
Running from demons in WNY
Hillbilly bike Offline
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Running from demons in WNY
Honda and others use a similar rocker arm on SOHC 4 valve engines... The late model Moto Guzzi 4 valve head has two valves opened by very short push rods. The cam being located in the head, to the side and slightly .... Push rods are ok so long as they don't interfere with proper port design..

Guzzi 4 valve initial design. Latest 4 valve is similar but with gear cam drive..

[Linked Image]


650 Triumph modified production LSR record holder 133.1 MPH... Twin 650 engine Triumph LSR that goes sorta fast...
Re: 880cc 12 Valve? [Re: Hillbilly bike] #739009
06/17/18 8:32 pm
06/17/18 8:32 pm
Joined: Feb 2014
Posts: 441
Cork Ireland
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chaterlea25 Offline
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Cork Ireland
Hi All,
[quote][/quote] I believe it was the Honda CX 500 which used an OHV, four valves per cylinder. Two push rods per cylinder. Each push rod would activate the "Y" shaped rocker arm that opened and closed two valves simultaneously.

In motorcycle terms the 4 valve pentroof combustion chamber was used on Rudge engines from 1925
(and Triumph Ricardo models for a couple of years)
Rudge also pioneered full radial valve engines, and also used a combination of parallel and radial valve operation

Back then the smaller lighter valves were partially in a bid for reliability but had the bonus effect of better breathing
Rudge racing results speak for themselves, the road bike models (as I have ) do not hang about either smirk
Believe me there was a need for those 8inch brake drums ohno

John

Re: 880cc 12 Valve? [Re: DMadigan] #739046
06/18/18 2:25 am
06/18/18 2:25 am
Joined: May 2013
Posts: 743
Overland Missouri
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old mule Offline
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Overland Missouri
I really like your design and appreciate the work that must have gone into it.

Re: 880cc 12 Valve? [Re: DMadigan] #739089
06/18/18 2:59 pm
06/18/18 2:59 pm
Joined: Jan 2004
Posts: 3,700
ca, us
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DMadigan Offline OP
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DMadigan  Offline OP
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ca, us
The "Y" rocker would not be applicable in this case as the tubes are currently between the cylinders. Putting the pushrods on the centre of the cylinder axis would require new cams, case surgery and splitting the intake runners around the tubes. So the rockers are like the Guzzi but with the rockers and pushrods outboard of the valves.
The ports are the major limiting power factor. The head could be fixed with a narrower two valve design and better ports but narrowing the valve angle would make the head taller and becomes a fit problem under the tank. The four valve allows the narrower valve angle without raising the height.
I bought a 3D wax printer for another project so this project may become real.



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