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Anyone know where to get oversized valves? Not interested in paying $ 430 + for 24 valves if I dont have to. Thanks
looking for cheaper valves
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RCM is $280 for 36mm Intake 31mm Exhuast
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On rcm there is no option to buy
You might consider just enlarging one intake and one exhaust valve per cylinder, particulary if the stock valves are in good shape. If nothing else it will cut down on valve to valve shrouding.
I can't seem to decide whether to do this via enlarging the short runner valve or the long runner valve although am leaning towards the short runner even though Vizard's Polyquad article sort of contradicts this:
http://www.motortecmagazine.net/article.asp?AID=1&AP=1
If the page changer can't be found just change the number on the end of the URL.
Here is more info:
http://books.google.com/books?id=KA...Q6AEwCTgK#v=onepage&q=vizard polyquad&f=false
This polyquad approach is controversial particularly in regards to enlarging just one exhaust valve:
http://speedtalk.com/forum/viewtopic.php?f=1&t=28614&start=30
http://www.allpar.com/fix/holler/polyquad.html
I can't seem to decide whether to do this via enlarging the short runner valve or the long runner valve although am leaning towards the short runner even though Vizard's Polyquad article sort of contradicts this:
http://www.motortecmagazine.net/article.asp?AID=1&AP=1
If the page changer can't be found just change the number on the end of the URL.
Here is more info:
http://books.google.com/books?id=KA...Q6AEwCTgK#v=onepage&q=vizard polyquad&f=false
This polyquad approach is controversial particularly in regards to enlarging just one exhaust valve:
http://speedtalk.com/forum/viewtopic.php?f=1&t=28614&start=30
http://www.allpar.com/fix/holler/polyquad.html
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very interesting on the polyquad head... only probley I see is with the secondaries and butterflies causing a issue..
I would imagine the larger valve to be on the secondaries side to take advantage of more flow and more top end power when seeing boost. but since it closes below whatever its set to usually around 4k most people would set it to take advantage of the low end it wouldn't really let air into that valve to make the swirl for added low end.
then if you put it on the long runner which is always open the air will flow more to the short valve when its opened above 4k so this will take away the effects the larger valve and possibly stop any added top end power.
making the SHO a polyquad would probley only work on the bottom end and not add to top end because the only reasonable way to make it would would be to use it on the long runner which I would think would only add some bottom end and not help any top.
however im not real sure since the exhaust still would try and swirl. and if you don't some bowl shaping and the such you might be able to help influence it still.
I would like to try it out and see what happens but I think I would be much to inclinded to put it on the short runner only.
in this case seems like the intake is the problem here and it might be best to only go bigger valves on all of them and not just one side.
im sure if this would have made a difference given the SHOs intake setup Yamaha would have done it or maybe even tested it somewhere
I would imagine the larger valve to be on the secondaries side to take advantage of more flow and more top end power when seeing boost. but since it closes below whatever its set to usually around 4k most people would set it to take advantage of the low end it wouldn't really let air into that valve to make the swirl for added low end.
then if you put it on the long runner which is always open the air will flow more to the short valve when its opened above 4k so this will take away the effects the larger valve and possibly stop any added top end power.
making the SHO a polyquad would probley only work on the bottom end and not add to top end because the only reasonable way to make it would would be to use it on the long runner which I would think would only add some bottom end and not help any top.
however im not real sure since the exhaust still would try and swirl. and if you don't some bowl shaping and the such you might be able to help influence it still.
I would like to try it out and see what happens but I think I would be much to inclinded to put it on the short runner only.
in this case seems like the intake is the problem here and it might be best to only go bigger valves on all of them and not just one side.
im sure if this would have made a difference given the SHOs intake setup Yamaha would have done it or maybe even tested it somewhere
Then to all those thoughts add having different short and long runner cam profiles a la SHOnut's TriFlo's that everyone is running now. There are a few indications that lifting the intakes at different rates tend to unshroud each other, but what would that do to the remainder of the polyquad concept given we close one runner off below 3800 rpm?
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Rcm emailed back about taking 4-6 months for the oversized valves to be in. At about half the price of other places im willing to wait. Guess ill be throwing stock heads on until they valves become available 
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Thinking about it I think the way the intake works is much like a polyquad head since the air is directed to the long runners under 4k and then short and long runners can pull above 4k even tho mist air will flow to short runners at that point. I may get only half the oversized valves and give it a shot after all. Maybe get sone triflow cams down the road to help it swirl more.
You can get a bit of the triflow cam effect by adjusting the lash on the valves on the primary runners to the maximum gap and the short runner valves to the minimum gap.
