Boygofast 47mm sleeved cylinder info



gary55

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Nov 27, 2012
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3,065
It didn't touch even without a head gasket lol.
Wow. If it didn't touch 1/16" solder without a gasket you got some milling to do. If it would have just touched it with no gasket then .8mm removed would have got you to 1.6mm or 1/16" with a .8 copper gasket. Check my math but I think if you are already using a single base and getting these numbers 1mm could get you to a starting point. If your using 2 base gaskets go to 1 and check again before any milling.
 

Spare_Parts

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Nov 29, 2017
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1,190
Just one gasket. Might pull out an old piston to see if it comes up different. The piston is zeda or cdh, that's all I buy but you never know what you end up with. This cylinder is 1mm taller then the zeda. Also, even with the zeda cylinder and Fred head I only used 1 base gasket. Squish was .7x mm with a .8 copper head gasket torqued to 80 inch pounds.
 

GreasyChris

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Jan 3, 2019
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I've got the same cylinder and the same problem the piston sits extra low in the jug at tdc. I've tried it with along rod crank and short rod crank and they both sit in the same low spot. I thought of milling the top as well but wasnt sure how that would go with the steel sleeve. I'm gonna have to use the glass and sand paper method when I do it.
 

Street Ryderz

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Oct 14, 2016
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I've got the same cylinder and the same problem the piston sits extra low in the jug at tdc. I've tried it with along rod crank and short rod crank and they both sit in the same low spot. I thought of milling the top as well but wasnt sure how that would go with the steel sleeve. I'm gonna have to use the glass and sand paper method when I do it.
Holy sh*t deck it down a mm with sand paper,good luck that's a job!End mill with a fly cutter or even a drill press would do it,I've used a belt sander in a pinch with the deck flat and rotate the cylinder constantly with even pressure as it cuts away.
 

Spare_Parts

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Nov 29, 2017
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1,190
Holy sh*t deck it down a mm with sand paper,good luck that's a job!End mill with a fly cutter or even a drill press would do it,I've used a belt sander in a pinch with the deck flat and rotate the cylinder constantly with even pressure as it cuts away.
Table top belt sander is the plan.
 

gary55

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Nov 27, 2012
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3,065
I do them all the time with a table top. Using the method Ryderz described abv. constantly rotating with light even pressure. It doesn't take much time but maybe a little more with the steel sleeve. Not sure how it will work with different materials could get tricky. I generally check the progress 3 to 4 times while taking them down to within .15 to .2mm of the target with the belt, then finish on the disc holding the jug center on the disc makes a beautiful final finish.
 

Spare_Parts

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Joined
Nov 29, 2017
Messages
1,190
I do them all the time with a table top. Using the method Ryderz described abv. constantly rotating with light even pressure. It doesn't take much time but maybe a little more with the steel sleeve. Not sure how it will work with different materials could get tricky. I generally check the progress 3 to 4 times while taking them down to within .15 to .2mm of the target with the belt, then finish on the disc holding the jug center on the disc makes a beautiful final finish.
Exactly what I was thinking of doing. Have some nice 220 for the disk.
 
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