Windowed piston

DieselTech

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What do I need to know to make a windowed piston for a reed valve engine build? Like window location, window size, shape of window? I'm planning on using a 49mm steel sleeve cylinder & either g2 reeds or the cdh oz reed set up. Any help or ideas would be appreciated.
 

Cannonball3

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I have made 2. I used the opening limits found on the common twin hole piston. I however made a single hole a bit larger than a single hole on the twin hole piston. Idea was not to weaken the piston, and in theory I think,
lowering the primary crankcase compression. All that said the single home made piston runs as well or slightly better
it seems. I have run both in the same type engine. The pistons with the huge single hole, dont look like a good idea to me.
 

Karl Snarl

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What do I need to know to make a windowed piston for a reed valve engine build? Like window location, window size, shape of window? I'm planning on using a 49mm steel sleeve cylinder & either g2 reeds or the cdh oz reed set up. Any help or ideas would be appreciated.
I use the double window method( paint marker used to mark where while engine is together. I just smear it through the intake). The middle pillar keep the piston stronger. Make sure you round all edges to prevent cracking. Then I drop the floor of the intake and port match to the reed housing. I open the exhaust to try to make it 40% or close to the new intake size, larger ( than the intake). Its supposed to be the best ratio from what I have read.
 

DieselTech

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Ok thanks everyone for the info, I'm trying to figure this out for my next 79.5cc build. I got all these engine parts from friends breaking them & leaving me there broke stuff. With all the good parts I'm going to build me another engine.
 

Karl Snarl

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Ok thanks everyone for the info, I'm trying to figure this out for my next 79.5cc build. I got all these engine parts from friends breaking them & leaving me there broke stuff. With all the good parts I'm going to build me another engine.
Im waiting on a shop press. I'll be pressing bearings in the case soon as it arrives. If you have enough parts, start trying to balance the crank better. I'm going to be working on that too.
 

DieselTech

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Yea thanks to @Street Ryderz he posted that crank balance video, I'm going to attempt to balance a crank. I know I can handle it, lol just dont know if drill press will handle it. So the bearings for crank are pressed in case? Could i use my bearing press to pull the bearings in the case?
 

Karl Snarl

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Yea thanks to @Street Ryderz he posted that crank balance video, I'm going to attempt to balance a crank. I know I can handle it, lol just dont know if drill press will handle it. So the bearings for crank are pressed in case? Could i use my bearing press to pull the bearings in the case?
Yeah, pressed in and out. I pracitced pulling from an old case with my puller. Just in case I screwed up and needed to pull 'em back out. Its the hammer slide style, just cranked the case half in the vice and went to town. Use a colbolt drill bit when drilling the crank. They are hard af and will drill through it with ease ( keep lubed and cool for best results)
 

noah9988

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Do they sell 49mm pistons for these engines? I'm looking into reed valves.
 

DieselTech

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Windowed pistons for the 49mm, no not that I know of yet, cdh has mentioned about offering one, but as of this time no. You will have to cut your own window in piston I believe.
 
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