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Discussion Starter #1
The new pistons are in for those that requested them.

56 and 57mm varieties...get'em while they are hot.

Well actually...if you haven't requested them already...it's too late. But I can order more if there is sufficient interest from the slow bikes ...errr.. people that don't have them. To tell the truth..I'd prefer it if only rich people ordered them cause so far I lose money on every set I sell. But not much, so don't go making charity offers.

Here's a pic before polishing.



Changes to the 56mm type are .015" deeper valve pockets so users should be able to use a thinner head gasket and still have .005" more valve/piston clearance. Claying is of course highly recommended before choosing your gasket thickness.

Changes to the 57mm type include .015" deeper valve pockets and setup for a thinner wiseco ring set. And of course 1mm larger for 209cc.
JohnnyB
 

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Discussion Starter #3
John,
With these little 200cc twins the bore and stroke is so small that it's difficult to make compression...you have to stuff the piston way up in the head. The notches are to clear the spark plug electrode. Pete T. is I'm sure doing similar things to his Duc pistons making big compression.
The reason for the size and shape of the notch is of course one of my trade secrets.
JohnnyB
 

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HUMMMMM,

I use the same piston in the Ducati as Pete does and I can tell you that it does not have a notch in it. The only thing Bruce-bcm-does is hog out the areas where the valves are. They are J&E pistons, very light and very dome like. Just like you are's......

Champ
 

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Discussion Starter #5
Pete T. probably only does it to his REALLY fast Ducatis. I even discussed the issue with him before I decided what to do.
JohnnyB
 

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Like JohnnyB said its a lot harder to get compression on a smaller displacement. You have one piston thats about 20mm bigger on even a small (250 with 74.0 x 57.8 mm) ducati then a piston that represents only half the displacement (becuase its a small twin). It doesn't matter who says it, if you bike was a single cylnder 50cc your piston would be even taller to get the same compression as a larger piston.

In regular person terms, You have to fill more of the whole and then you make room for spark plug. Or you could just ask Bruce to make your bike faster, enjoy your winter, and play around on forums.

Aaron
 

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>Or you could just ask Bruce to make your bike faster, enjoy your winter, and play around on forums<

Yea..... That's it !!!


Champ
 

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JB, send me the pistons and a bill.

I'm crazy lately moving my office, shop, and wife and life.

Scott
 

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Mr. Branson,
Send my pistons and send my bill to Scott. No really, I need them quick, I need to send them to someone who can take the notches out.

Aaron
 

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Discussion Starter #10
Aaron,
I've got an angle grider with some 36 grit disks...I can take that notch right out the piston.

Scott,
Figured you were busy. I'll send them along after polishing.

JohnnyB
 

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Discussion Starter #13
Hey... I ain't no beginner at this.
They have some CNC milling done underneath the dome to reduce weight. Even at 4mm larger than OEM pistons, and with a higher dome they are 19% lighter than stock pistons. Forged pistons evidently can be made lighter than stock cast pistons.
Damn straight walled wiseco piston pin is 6 grams heavier than the OEM tapered wall pin though. Can't get the size I need in tapered wall...and mine are a bit longer than stock.
The larger 57mm pistons at 118 grams are just a tad lighter than the 52mm stock pistons.
Of course the phase 5 piston design is floating around in my head already, more compression but probably a few grams heavier, depends on how much I can get taken off the bottom side. Might have to look into custom piston pins to get the weight down there.
JohnnyB
 

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JohnnyB,
I think I'm ready for Dyno time. I'm curious how my 3inch discs breath compared to the 4inch. I will say the power starts light years before it did. I would still like to investigate some over size valves but am limited to Honda stuff. I will sift through some different Honda heads while picking up the 200 barrels. Can't wait to get back from Daytona to get the big boy pistons in.

Aaron
 

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Discussion Starter #18
Scott,
No I haven't. I'm dicking around, still have to polish them.

I've been working on this:

http://www.jrbranson.com/pvl-test-1.wmv

That's a windows movie format...not sure if you can view it or not.

Here's a picture of it:



Works like a Mofo. If you can view the movie note how stable the timing is...by watching the bolt holes in the rotor while the timing light is on it. Yes that rotor is turning way fast.

I hope to obtain the parts to sell these kits in the not too distant future. This was a very preliminary test, have no idea where the timing actually was..gotta figure out a good way to do that...and the plug wires had no caps...just some of the bare wire wrapped around the end of the plug.
JohnnyB



Edited by - jbranson on Dec 21 2004 2:51:28 PM
 
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