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What type of work is done on the upper case to increase the flow from the transfer ports, if any? For some reason I just thought about this over the weekend. Mine is tore down due a crank failure and while looking at the case it dawned on me that it is identical to my stocker. The transfers on the cylinders are opened quite a bit but the matching area in the case only has one 4 or 5mm hole in it . There is another indented hole that isn't a through hole for each cylinder also.
What type of work is typically done in this area for improvements? I know you need to match your gasket to the case and then the cylinder to avoid any type of flap or obstruction. Would opening up the holes help or would it simply reduce the air velocity?
 

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I flipped the cylinders over (cub) and matched the gasket to the cylinders. Then placed the gasket on top of the cases and carefully scribed a line in the case to match the gasket. Then cut the cases to the scribe line. Once the first cut was made, i put a little lithium grease on the cylinders, pressed them down by hand to see what was needed. After 3-4 times it was pretty smooth. Just be careful how deep (toward the crank) you go with the cutting. The deeper you go into the case, the thinner the material is, especially on the flywheel side.
I hope this helps...Rick
 

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QUOTE (banshee217 @ Sep 22 2008, 08:17 AM) index.php?act=findpost&pid=11270What type of work is done on the upper case to increase the flow from the transfer ports, if any? For some reason I just thought about this over the weekend. Mine is tore down due a crank failure and while looking at the case it dawned on me that it is identical to my stocker. The transfers on the cylinders are opened quite a bit but the matching area in the case only has one 4 or 5mm hole in it . There is another indented hole that isn't a through hole for each cylinder also.
What type of work is typically done in this area for improvements? I know you need to match your gasket to the case and then the cylinder to avoid any type of flap or obstruction. Would opening up the holes help or would it simply reduce the air velocity?
T indented hole you are talking about can be drilled out for the oil to reach the bearing ,same as the other one,I always drill both out a little bigger for extr lube,and you can cuo back the lip on the oil trough,just make sure you mill the through a little deeper for oil to stay in and oil the bearing,i use a small ball burr and cut the trough a little deeper and angle it toward the wholes, Hope this helps.
 

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QUOTE (tedd1 @ Sep 26 2008, 08:43 AM) index.php?act=findpost&pid=11805I flipped the cylinders over (cub) and matched the gasket to the cylinders. Then placed the gasket on top of the cases and carefully scribed a line in the case to match the gasket. Then cut the cases to the scribe line. Once the first cut was made, i put a little lithium grease on the cylinders, pressed them down by hand to see what was needed. After 3-4 times it was pretty smooth. Just be careful how deep (toward the crank) you go with the cutting. The deeper you go into the case, the thinner the material is, especially on the flywheel side.
I hope this helps...Rick
when you port the cases to the cub there is a pretty big difference to match then the stockcylinders.better flow once you do the case porting
 

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This is where it becomes a little tricky.... some setups like a little more case volume, and others hate it. It all depends on your pipe and carb selection? We have to match those variables; unless you give us a blank slate.
 

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isnt there a case volume ratio where motor like to be at like a lower end compression ratio? we'd talked about it on ps a long time ago but never really got anywhere.

i like a high lower end cranking pressure. just matcht he ports on the case half and leave them as thick as possible but still seem to have a nice flow upwards. stock cylinders with small transfer port tunnel openings cubs with minimal work on there triple's just cleaned up. intake's windows on stocker with thicker center sections for reliability,, but who knows what going on under the piston and how the crank's rotation and webbings effect the up push of fuel air? lots of turbulence from rods flingin around na crank webs with big huge cut outs in them..???
 
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