piston mods to lighten weight see pic

Spare_Parts

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Again this is just Rob's fuckery this is the piston shown and it's description states not for reed use.https://zedamotorsports.com/collections/cylinders/products/zeda80-super-stock-r-ported-cylinder-no-reed-needed This one is his windowed version and he call's the extra holes oilers.https://zedamotorsports.com/collections/cylinders/products/fully-finshed-ported-reed-z80-cylinder-round-port If there were finger ports in the jug then maybe but as I pointed out they are under the pins so snaging would be very likely.
I'm not arguing about Rob doing dumb sh*t to sell parts lol.
 


darwin

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It would be interesting to have 1 motor stock and another w/that modification. See how they run and how long they each last. Just an interesting experiment. Weird that smokers for a hundred years or so haven't done it so far. The Japs have had their best and brightest designing some serious 2 stroke m/c's and scooters all along.
 

JerboaJohn

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'Rob's fuckery' lol I like that term.
holes in the skirt can't help any oiling. like Furry's at the wristpin, yes! I've seen that b4
20 holes @ 4mm depth. if they are 5mm (at most) abt 1.6grams but I think those are 1/8" so weight savings only about 0.65grams,, worthless really
Aluminum weighs 2.699 gram per cubic centimeter. that's a lot of material to remove

I asked him how much it actually weighs lol. who knows if I'll get a reply tho
 
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Street Ryderz

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I'm not arguing about Rob doing dumb sh*t to sell parts lol.
I'm not trying to argue with you bro,just pointing out for every one that he does some weird sh*t!Makes claims with no validity and preys on those whom don't know.Theon Oak hill does 3 holes in the piston on the intake side that line up with finger type boost tracks above the intake window with their main purpose to extend the duration.
 

Steve Best

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No point in arguing "how many fairies can dance on the head of a pin?" Jus' DO IT!

These pistons cost what? $10? DO IT! Drill the puppy. Drill an old one if you have to.
This is a Blaster piston I wanted to know if enlarging the back transfer would have an effect:
87014

Well used $100 piston, going under the knife, er, drill.
87015

Pilot drilled
87016

It's like 15 minuttes to pull a jug on a Blaster, less than 10 minutes to do it on a China Girl.
87017

I tested it between all operations. It actually worked better every time so far.
87018

Here you can see the port match up just below TDC.
87019

TDC, cannot match up the piston window to the cylinder window or there would be no piston skirt support. These pistons are weak so we don't touch the lower skirt. Engine was rippin' pretty good here. So if a little was good, let's keep going:
87020

Starting to act a bit odd. Lots of rev but torque disappearing. Why?
87021

Strange stuff happening now. Rev happy but kinda flat. How many times has this old piston been in and out of this motor?
87022

Little by little I filed the top port larger to see what it would do. Into the motor, test it, back out and file.
87023

Mister Happy Face! Well, not really. It was kinda sucky by here. This took up a sunny Saturday afternoon and I learned something. This piston was in and out of the motor about 6 times. Piston and bore were do for a replacement but still worked OK, so let's learn something from the last day of its life. Now, the things you can do with epoxy:
87024
 

Street Ryderz

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Oct 14, 2016
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3,032
No point in arguing "how many fairies can dance on the head of a pin?" Jus' DO IT!

These pistons cost what? $10? DO IT! Drill the puppy. Drill an old one if you have to.
This is a Blaster piston I wanted to know if enlarging the back transfer would have an effect:
View attachment 87014
Well used $100 piston, going under the knife, er, drill.
View attachment 87015
Pilot drilled
View attachment 87016
It's like 15 minuttes to pull a jug on a Blaster, less than 10 minutes to do it on a China Girl.
View attachment 87017
I tested it between all operations. It actually worked better every time so far.
View attachment 87018
Here you can see the port match up just below TDC.
View attachment 87019
TDC, cannot match up the piston window to the cylinder window or there would be no piston skirt support. These pistons are weak so we don't touch the lower skirt. Engine was rippin' pretty good here. So if a little was good, let's keep going:
View attachment 87020
Starting to act a bit odd. Lots of rev but torque disappearing. Why?
View attachment 87021
Strange stuff happening now. Rev happy but kinda flat. How many times has this old piston been in and out of this motor?
View attachment 87022
Little by little I filed the top port larger to see what it would do. Into the motor, test it, back out and file.
View attachment 87023
Mister Happy Face! Well, not really. It was kinda sucky by here. This took up a sunny Saturday afternoon and I learned something. This piston was in and out of the motor about 6 times. Piston and bore were do for a replacement but still worked OK, so let's learn something from the last day of its life. Now, the things you can do with epoxy:
View attachment 87024
Looks like by the time you got to the happy face it lost vacume velocity/pressure from opening closer to when the ports were covered above the piston.
 
Joined
Sep 26, 2018
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156
About unbalanced pistons, should we attempt to balance a windowed piston by drilling out the piston between the transfers and exhaust? Just curious. I've been hitting a power drop after 7000 rpm for some reason so I'm opening her up for some modifications.
 

FurryOnTheInside

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Sep 23, 2013
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About unbalanced pistons, should we attempt to balance a windowed piston by drilling out the piston between the transfers and exhaust? Just curious. I've been hitting a power drop after 7000 rpm for some reason so I'm opening her up for some modifications.
I can't imagine that piston imbalance is why it peaks low..
I would first think of the flow restrictions: stock air filter box has only a small inlet, the stock port durations might not be open long enough to get the a/f transferred or exhaust gases out, small rse reed, crankcase not properly matched to the transfers, etc... then tuned pipe length.. But idk the specs of your engine.
 
Joined
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Messages
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I can't imagine that piston imbalance is why it peaks low..
I would first think of the flow restrictions: stock air filter box has only a small inlet, the stock port durations might not be open long enough to get the a/f transferred or exhaust gases out, small rse reed, crankcase not properly matched to the transfers, etc... then tuned pipe length.. But idk the specs of your engine.
Yes, I think my blowdown is too small tbh. I'm just wondering if I should do that while I'm in there
 

FurryOnTheInside

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Sep 23, 2013
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3,485
Yes, I think my blowdown is too small tbh. I'm just wondering if I should do that while I'm in there
If you've widened the exhaust port like most modders here then it's already very close to the edge of the skirt, I wouldn't think there's any room for holes.. and as noted earlier in the thread, tiny holes don't remove much weight at all anyway.
The window on the intake side is at the furthest point from the pivot, but holes in the ex side skirt would be closer to the pivot and therefore less effective for balancing the piston.

But I wouldn't think the imbalance would be restricting power above 7000rpm anyway, and more likely to just increase cylinder wear, if anything.
You might make the ex side of the skirt thinner if you really want to try something. My thin skirted piston hasn't cracked yet.
 
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