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 Post subject: Pilot Heads?
PostPosted: Wed Aug 15, 2007 7:49 am 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
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This post is to see if their is any interest in heads for the Pilot with interchangeable domes like the cool head?

I am told Honda discontinued the stock head I don't know if its ever coming back, looking for a head count so if we get a batch made we know what the interest is, no idea on the price just yet but I have to assume it will be about what the cool heads cost.

Their would be dome options, pump gas and race gas.

The heads would look similar to this one http://pilotodyssey.com/duncanheadhtm.htm

The heads will out perform the stock heads with increased cooling capacity and surface area, an improved combustion chamber design and tighter controls on the squish clearance, more on the technical details and advantages in the future.

Their also might be a option to salvage your damaged stock head, this is still in development and has yet to be tested my biggest question is if the stock casting is ridged enough to clamp and properly hold the dome, if this works out it will use the same domes as the other new head does.

http://pilotodyssey.com/PO/viewtopic.php?t=3380




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 Post subject:
PostPosted: Wed Aug 15, 2007 8:49 am 
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Joined: Mon Jun 11, 2007 9:35 am
Posts: 31
Location: Fort Worth,Texas
You know I'm in
3 maybe 4
TD


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 Post subject:
PostPosted: Wed Aug 15, 2007 10:10 am 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Ok here is some info on heads and design, read below everybody can benefit from a improved design of the new heads.


Quote:
Researchers have found that it is the gases at the very outer limits of the combustion chamber, called the 'end gases', that self-ignite to cause detonation. These end gases are heated by the surrounding metal of the piston crown and combustion chamber, and also by the heat radiating from the advancing spark-ignited flame. If the spark flame reaches the outer edges of the combustion chamber quickly enough, these end gases will not have time to heat up sufficiently to self-ignite and precipitate detonation. Herein lies the key to prevent detonation - keep the end gases cool and reduce the time required for the combustion flame to reach the end gases.

The most obvious step that would satisfy the second requirement is to make the combustion chamber as small as possible, and then place the spark plug in the center of the chamber. Naturally the combustion flame will reach the end gases in a small combustion space more quickly than if the chamber were twice as wide. Additionally, a central spark plug reduces flame travel to a minimum.

In meeting the second requirement, the need to keep the end gases cool can also be accommodated. If we move the combustion chamber down as close to the piston crown as possible, no combustion will occur around the edges of the chamber until the piston has traveled well past TDC (Top Dead Center). This large surface area acts as a heat sink and conducts heat away from the end gases, preventing self-ignition.

The chamber just described is called a squish-type combustion chamber because of the squish band around its edge. Originally, the squish band was designed to squish the fuel/air charge from the edges of the cylinder toward the spark plug which, of course, it still does. The fast moving gases meet the spark plug and quickly carry the combustion flame to the extremity of the combustion chamber, thus preventing detonation.

Since that time, more benefits of the squish chamber have come to light. The mixture being purged across the combustion chamber from the squish band homogenizes the fuel/air mixture more thoroughly and also mixes any residual exhaust gas still present with the fuel charge. This serves to speed up combustion by preventing stale gas pockets from forming. Such pockets slow down, and in some instances can prevent, flame propagation.

Turbulence caused by the squish band also serves to enhance heat transfer at the spark-initiated ,flame front. Without proper heat transfer, jets of flame would tend to shoot out toward the edges of the combustion chamber, prematurely heating the surrounding gases to start off the cycle leading to detonation.

Rapid combustion has other advantages besides controlling detonation. With an increase in combustion speed there is, of necessity, a corresponding decrease in spark advance. The closer to TDC (Top Dead Center) we can ignite the charge, the less negative work we have to do compressing a burning charge that is endeavouring to expand. Also there is less energy loss in the form of heat being transferred to the cylinder head and piston crown.

When less heat is conducted to the head and piston, the Engine runs cooler and makes more power. A side benefit resulting from the cooler piston also enhances the power output. A cool piston does not heat the charge trapped in the crankcase as much, therefore a cooler, denser fuel/air charge enters the cylinder each cycle, to make more power.
If you think about it, you will see that the compact squish type combustion chamber also contributes to a cool piston by confining the very intense combustion flame to about 50% of the piston crown just before and after TDC (Top Dead Center).

Engine designers have known about these things for a considerable time. This is why you will find the best racing engines follow the squish design. Also you will notice that these engines have a very small bore in relation to their stroke, as this too cuts down the size of the combustion chamber and reduces the area of piston crown exposed to the combustion flame.

In an effort to minimize cylinder and piston distortion, some manufacturers have chosen to use an offset squish type combustion chamber (see pic below). The exhaust side of a two-stroke cylinder and piston is always the hottest, even though cooling air flow is much better here than on the back (inlet side) of the Engine. There are several reasons for this, all associated with the passage of very hot (630°C) exhaust gas through the exhaust port. The escaping gas heats the exhaust port and cylinder wall as well as the side of the piston. This can cause the piston to expand abnormally and in some circumstances to seize. To take care of this possibility, the manufacturer may choose to increase piston to cylinder clearance, but this may not be desirable as extra clearance can increase leakage past the rings and usually results in high piston wear. A safer step is to move the combustion chamber to the rear of the head. If this is done, the front of the piston crown is shielded from the combustion flame by the squish surface. Then, when the front of the piston is heated during the exhaust stroke, it will not expand so far due to its being initially much cooler.

Several two-stroke engines are produced with squish and offset squish chambers, but unfortunately mass production usually reduces their effectiveness. It is a very difficult task to keep tolerances of closer than about 0.2mm in production. Therefore you find many engines with a squish clearance of 1.3-1.8mm instead of the 0.6-0.8mm clearance that is required.


Image

Quote taken from Two Stroke Performance Tuning


With the stock heads I usually find the squish in excess of .070


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 Post subject:
PostPosted: Wed Aug 15, 2007 10:19 am 
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Joined: Mon Jul 02, 2007 10:40 am
Posts: 22
Location: New Orleans, LA and Pensacola, FL
I'd suggest you contact Kelsey at http://www.2strokeheads.com. Heads are his major line of products, and if the quantities are right, he might make them a regular in his line. He also might be able to adapt an existing design of his to a Pilot/Odyssey, and he may do one-offs as well. He would be my first contact.


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 Post subject:
PostPosted: Wed Aug 15, 2007 2:29 pm 
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Joined: Tue Dec 16, 2003 2:45 pm
Posts: 885
I would take one head/domes


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 Post subject:
PostPosted: Wed Aug 15, 2007 3:31 pm 
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Joined: Thu Jun 16, 2005 7:19 pm
Posts: 2245
Location: Chandler, AZ
I would be interested in one


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 Post subject:
PostPosted: Wed Aug 15, 2007 5:50 pm 
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Joined: Tue Dec 16, 2003 4:54 pm
Posts: 1360
Location: Baltimore, Maryland
i would do at least one.


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 Post subject:
PostPosted: Wed Aug 15, 2007 9:20 pm 
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Joined: Tue Dec 23, 2003 10:31 pm
Posts: 5559
Location: New Jersey
Include me as well for 2 at least-is there a need for financing this I am open to help in this way as well Hoser.
Mabye a head for 350's in the future can be an option?


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 Post subject:
PostPosted: Mon Aug 20, 2007 2:20 pm 
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Joined: Mon Jun 11, 2007 9:35 am
Posts: 31
Location: Fort Worth,Texas
Hoser,

Have You heard anything from the machine shop on the Heads.

TD


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 Post subject:
PostPosted: Mon Aug 20, 2007 2:41 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
TD wrote:
Hoser,

Have You heard anything from the machine shop on the Heads.

TD


No I havent, I will send him a email tonight to see if he got my package today, I sent him my cool head a dome, stock head gasket and the 2nd stock head I started to modify.


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 Post subject: Pilot Head
PostPosted: Mon Aug 20, 2007 4:27 pm 
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Joined: Sat Dec 20, 2003 2:11 pm
Posts: 62
Location: Lewiston New York
Hoser I would be in for 2, and like Mudbogger, I might be able help with up front costs if needed.

Moregoodlier
Dan


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 Post subject:
PostPosted: Tue Aug 21, 2007 10:49 am 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Update:
He has the heads I sent just has not had a chance to look at them yet.


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 Post subject:
PostPosted: Tue Aug 28, 2007 5:02 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Update, Just got the one head back from my buddy Pete he took it to work and welded it up, I will try to machine it up tomorrow.


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 Post subject:
PostPosted: Fri Aug 31, 2007 9:29 am 
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Joined: Mon Dec 15, 2003 2:40 pm
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Location: Chicago
I finished the machining and its ready to install.


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 Post subject:
PostPosted: Fri Aug 31, 2007 9:31 am 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Next to stock head.


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 Post subject:
PostPosted: Fri Aug 31, 2007 9:32 am 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Using a modified 47cc dome and a stock head gasket it yields 170 psi static compression on the wifes Pilot.


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 Post subject:
PostPosted: Fri Aug 31, 2007 6:01 pm 
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Joined: Mon Jun 11, 2007 9:35 am
Posts: 31
Location: Fort Worth,Texas
Hoser,

That looks Good,

Is that the dome from your coolhead,

TD


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 Post subject:
PostPosted: Fri Aug 31, 2007 6:36 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
TD wrote:
Hoser,

That looks Good,

Is that the dome from your coolhead,

TD


Yes it is one of my old experimental domes, I had to modify it to work with this head, I reduced its thickness so it cant be reused in a cool head.. I think I have a way to avoid this for most stock heads, this one was cut way down on its gasket surface when I received it, much further than I think you will see most stock heads that have been modified.

I still need to install it on my wifes Pilot with a fresh head gasket then I will pressure test the coolant loop for the head and cylinder to make sure no leaks then fill with coolant and test run, heat cycle a bunch of times etc.


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 Post subject:
PostPosted: Thu Apr 24, 2008 5:24 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
It looks like the heads are starting to come together who wants one, or more?

See the thread here http://pilotodyssey.com/PO/viewtopic.php?t=3891

Some teaser pics :-) We need a head count for the first batch...

Image

Image


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 Post subject:
PostPosted: Thu Apr 24, 2008 7:40 pm 
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Joined: Fri Feb 29, 2008 1:51 am
Posts: 2703
Location: Upland, Ca
I'm in I want one


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 Post subject:
PostPosted: Thu Apr 24, 2008 11:10 pm 
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Joined: Sat Aug 12, 2006 9:02 pm
Posts: 533
Location: Bellevue WA I OWE Hoser $300.00
Im in


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 Post subject: Heads
PostPosted: Fri Apr 25, 2008 8:10 am 
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Joined: Tue Dec 16, 2003 7:22 pm
Posts: 400
Count me in for 2 or 3 if the price is right.. Nice work!

Pilotman


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 Post subject:
PostPosted: Tue May 06, 2008 6:03 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Heads are HERE :-)

http://pilotodyssey.com/PO/viewtopic.php?p=32787



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 Post subject:
PostPosted: Tue Nov 18, 2008 6:13 pm 
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Joined: Mon Dec 15, 2003 2:40 pm
Posts: 22512
Location: Chicago
Any feed back on these heads from their owners?


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 Post subject:
PostPosted: Thu Nov 27, 2008 12:43 pm 
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Joined: Fri Jan 04, 2008 1:01 am
Posts: 87
Location: California, Central Coast
hoser wrote:
Any feed back on these heads from their owners?


I have about 12 hours on my speedchaser head. It is on top a new Hoserized Honda cylinder and is running very strong. I have had no problems and highly recommend it! :-)


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