262XP Day

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Well does sinusoidal really describe it? I've often wondered.
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Yes it does. It represents position of the piston vs time. When you increase the rod length the wave changes, the piston spends more time near TDC and BDC for a given change in crank angle.

A longer rod ratio produces a more uniform piston velocity throughout its stroke. Thus a long rod produces lower peak piston velocities/accelerations/jerk etc. Generally, intake flow stagnates at sonic velocity. And since intake velocity through the ports is relatively proportional to piston speed, intake flow benefits from reduced peak piston velocity.
Engine design variables like stroke/bore ratios and rod ratios is an excercise in compromise. For low speed engines, a long rod is especially beneficial. It reduces peak piston velocities/accelerations and inertia loads on the rod and crank bearings. A long rod also minimises rod angulation and thrust load/friction losses at the piston skirt.
 
Randy,
Without doing the base&squish, just by doing finger and bridge, how much gain do you think that modd would bring?

And second, how close to perfect do you think the timings are on standard 262?

I also have a third question, do your guys now and then shave off the lower transfer a bit, or would it not mather at all?

I'm sure there would be gains.......I have no idea how much though.

For that saw........they are very good. And by studying the port layout of the 262, and considering the timing numbers, I'm sure ideas begin to form.....

Yes?

On this saw I barely touch the lowers.

But I do knock off the lip on many others.
 
I cannot believe you guys are even arguing about piston speeds, rod lengths, the shape of the speed of the piston....seriously? Have you nothing better to do? Why don't you go play with your kids or something?
Who's arguing? Just a conversation...
 
No it doesn't.

A sinusoid is perfectly smooth to my knowledge.
Im not here to agrue semantics. If you consider displacement vs angle it is. When I wrote my first response to you I could not see your pictures and didnt realize your graphs were velocity vs angle. It all depends on your perspective.
 
Not just fingers.......fingers and bridges.

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This is the swarf from the transfer work so far. For visual reference that tool is 7" long with the burr.

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I'm taking my lovely wife out for Sushi. She's been fasting and this is a great way to break her fast.

Later. :)
Nice work, Randy. What 5 axis cnc mill do you use for those bridge/finger ports?
 
Nice work, Randy. What 5 axis cnc mill do you use for those bridge/finger ports?
I know. They're fricken perfect looking.

The pics of those make me want to return my grinder and just sent all my saws to Randy.

Hence why he openly shares numbers. You can't really recreate.

Like Mozart giving you his music and you buying the same piano as him. You just ain't playing that concerto the same way.
 
I only check the serial number, 1 is the year, the two next is the week.

That is true, up to and including 1996.

From 1997 to about (haven't found the exact cutoff week yet) week 18 1999 the full year will be on the tag in addition. After that the year code is two digit, and there is one additional extra digit (to make room for more than 9999 saws in a given week - I have never seen that actually happen though).

The 262xp was made at least up to 2005/2006, for some markets (Israel and Russia identified). The last one to be discontinued likely was the 262xph, that was a special for the Russian Siberia market.
 
I know. They're fricken perfect looking.

The pics of those make me want to return my grinder and just sent all my saws to Randy.

Hence why he openly shares numbers. You can't really recreate.

Like Mozart giving you his music and you buying the same piano as him. You just ain't playing that concerto the same way.
This is exactly what I was thinking when I said you guys are over thinking. Randy does what he does because he WORKS so hard at perfection. TRIAL and ERROR!
 

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