T_Shee Posted June 11, 2010 Report Share Posted June 11, 2010 did a search and couldnt find anything useful in the allotted 8 pages. juggs are dune ported and i have it back apart to replace crank seal. i was wanting to port match the cases while i was at it and would like any input that anyone has. thanks Quote Link to comment Share on other sites More sharing options...
SAVAGE420 Posted June 11, 2010 Report Share Posted June 11, 2010 I will check to see if i saved the pics of mine. Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted June 11, 2010 Report Share Posted June 11, 2010 Take a base gasket and cut it out to match the porting on the bottom of the cylinders. Then flip it over and and trace the cut out onto the cases. Then grind the cases out to your lines and they are port matched. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted June 11, 2010 Report Share Posted June 11, 2010 Take a base gasket and cut it out to match the porting on the bottom of the cylinders. Then flip it over and and trace the cut out onto the cases. Then grind the cases out to your lines and they are port matched. x2 Quote Link to comment Share on other sites More sharing options...
J-Madd Posted June 11, 2010 Report Share Posted June 11, 2010 Take a base gasket and cut it out to match the porting on the bottom of the cylinders. Then flip it over and and trace the cut out onto the cases. Then grind the cases out to your lines and they are port matched. Not perfect, but here's a pic. It's only the second set of cases I've done. On the the first set (not pictured), I took a little too much out of. I matched it to gasket residue that was left on the case rather than the gasket - not realizing that some of the gasket outline was missing Gonna have to match the cylinders to the case now. Quote Link to comment Share on other sites More sharing options...
springer Posted June 11, 2010 Report Share Posted June 11, 2010 what kind of power increase would someone see from port matching the cases? are there other benefits?? Quote Link to comment Share on other sites More sharing options...
J-Madd Posted June 11, 2010 Report Share Posted June 11, 2010 2-4 HP is what I've read. Case porting, along with a fresh top end, picked up my stock chassis 421 Cub about half a tenth in 300 ft. BUT - different track, different conditions - so there is no way to know if it helped or not. I think it helped, because the track itself seemed a little bit slower than before, but I dunno... Quote Link to comment Share on other sites More sharing options...
T_Shee Posted June 11, 2010 Author Report Share Posted June 11, 2010 thanks for the info and pictures guys. i pretty much already had an idea on how to go about it (making template from gasket) just didnt know what to do about the lip down inside there with the hole in it for oil. i figured youd just want to smooth it out and by the pictures it looks like thats about it. how deep would you say you cut into them? i know the top part just depends on how the juggs are ported, but what about down in there an inch or so? Quote Link to comment Share on other sites More sharing options...
J-Madd Posted June 11, 2010 Report Share Posted June 11, 2010 My pics are definitely not perfect - I'm sure someone has a textbook example of how its done. I just tried to make a smooth transition from the bottom all the way up to the top of the case. Remember that the mixture is flowing upward through there. If I had a small step or lip I couldn't get to, I didn't worry about it much as long as it would let the mixture flow upward without hitting the "step" . I found that the more I tried to get the "steps" out, the more I ended up taking out of the case. You don't want to take it out past the gasket or you'll have a big step when the mixture hits the bottom of the cylinders (like my first set - not pictured.) I used a dremel cutting bit. It cut the aluminum like butter. Then I worked from coarse to fine sanding bits. Quote Link to comment Share on other sites More sharing options...
T_Shee Posted June 11, 2010 Author Report Share Posted June 11, 2010 My pics are definitely not perfect - I'm sure someone has a textbook example of how its done. I just tried to make a smooth transition from the bottom all the way up to the top of the case. Remember that the mixture is flowing upward through there. If I had a small step or lip I couldn't get to, I didn't worry about it much as long as it would let the mixture flow upward without hitting the "step" . I found that the more I tried to get the "steps" out, the more I ended up taking out of the case. You don't want to take it out past the gasket or you'll have a big step when the mixture hits the bottom of the cylinders (like my first set - not pictured.) I used a dremel cutting bit. It cut the aluminum like butter. Then I worked from coarse to fine sanding bits. right on. thanks for all your help j madd. i got a die grinder and some carbide bits so we will see what happens. Quote Link to comment Share on other sites More sharing options...
firebanshee Posted June 11, 2010 Report Share Posted June 11, 2010 Don't forget to rough up the bottom of the crank case so it mixes the fuel better. Quote Link to comment Share on other sites More sharing options...
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