Case reed porting advice

Spare_Parts

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#1
Looking for some advice to port a new cylinder for the zeda case reed engine. Looking to make more mid to top end power. Bought a new cylinder from JL Zeda and it's not the nicest I have seen lol. Anyway I plan to map out the stock ports and make a small degree wheel to do this the right way. One thing I'm not sure about is the third transfer, does it help? Also, is Jbweld good to use to seal up the intake port?

Any suggestions on port timing, size and shape is welcome.



 


Street Ryderz

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#2
Looking for some advice to port a new cylinder for the zeda case reed engine. Looking to make more mid to top end power. Bought a new cylinder from JL Zeda and it's not the nicest I have seen lol. Anyway I plan to map out the stock ports and make a small degree wheel to do this the right way. One thing I'm not sure about is the third transfer, does it help? Also, is Jbweld good to use to seal up the intake port?

Any suggestions on port timing, size and shape is welcome.



It's a shame Zeda's cylinders of late are not the quality they used to be!The transfer feed at the base and overall width don't line up with the windows and that makes it very hard to correct the short wall angle.JB weld will work to close up the intake but you want to bring it almost flush with the window and then cut the third transfer at the same height as the other two.Being that's it's case reed exhaust port and blow down is all you need to worry about for timming and their widths,window shape for the exhaust you want 26mm across the upper most portion like the diagram shows.The gray area when looking through from flange area is flat blending into the circular dia of flange.Blow down duration should be around 20 degrees.
Exhaust shape.jpg
 

Spare_Parts

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#3
Almost sent the cylinder back and got a cdh but figured they are the same casting anyway LOL.

The stock transfers are only about 20mn wide so do I just leave that alone and clean them up? Going to back cut them like you have show on here. Also, you probably know off the top of your head, what does 20° equal in mm of piston travel? Thanks for the picture of the port shape.
 

Street Ryderz

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#4
Almost sent the cylinder back and got a cdh but figured they are the same casting anyway LOL.

The stock transfers are only about 20mn wide so do I just leave that alone and clean them up? Going to back cut them like you have show on here. Also, you probably know off the top of your head, what does 20° equal in mm of piston travel? Thanks for the picture of the port shape.
On the Zeda jug's transfer wall angles are different and yes the window has to be wider in order to back cut an angle closely matching the other or the jb weld filet at the correct angle and probably easier on this jug.The 20 degrees is in relation to crank rotation so with your degree wheel find where the transfers open and bring crown up the 20 and that's where your exh port should open.The height of transfers vari a bit and the mm of travel doesn't work out linearly though linear measurements can be taken from the deck and Lambretta's calc used pretty easily.
 

Spare_Parts

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#5
I want the stock transfers to blow towards the intake port correct? If thats the case I can work it without the jb weld filet. This casting is horrible but it may work to my advantage.

Thanks for the help with this. Been trying to read Jennings book but always get interrupted.
 

Street Ryderz

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#6
I want the stock transfers to blow towards the intake port correct? If thats the case I can work it without the jb weld filet. This casting is horrible but it may work to my advantage.

Thanks for the help with this. Been trying to read Jennings book but always get interrupted.
Yes toward the intake.
 

Spare_Parts

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#7
Gave up trying to make a degree wheel lol. I ordered on from Amazon instead. Should be here Tuesday.
Found Lambretta's calculator so I can play around with that some. Also been reading a bunch of threads on here.
 

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