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Post by trenchy on Jul 31, 2013 12:07:52 GMT
so with an over bore these fit straight in a b12, but does anything alse need to be done for them to be used? obviously its better to use proper low comp pistons, but i just won some of these cheap on ebay so figure if theyre not as good as im after then I will get rid and do it proper.
can anyone help?
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greybush
Velociraptor
Posts: 27 
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Post by greybush on Aug 3, 2013 0:23:39 GMT
I am using them in my turbocharged bandit, 2mm over bore with .0025" piston to cylinder clearance. I just rounded over the sharp edges around the valve pockets to prevent hot spots. when I do my spare motor I am going to deck the block .040" to get the compression back up to about 9:1 Staight drop in at roughly 8:1 comprssion made the motor a little lazy off boost.
Hope this helps
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Post by Devilman on Aug 6, 2013 23:29:43 GMT
Only other thing that is worth doing, is either Decking the block as greybush says, as typically the Busa slugs are much shorter than gixxer slugs, resulting in a real low comp ratio. 1 possibility if you don't want to deck the block is to fit a short-stroke 750 "dot head", which have smaller combustion chambers and should bring up compression a bit to help off-boost performance.
The other downside of using busa slugs is that they are always down the bore slightly when at TDC, so the squish "band" is prettymuch ruined, which can also affect off-boost performance quite badly.
Greybush... are you planning on decking the top, or bottom of the block and by how much?
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greybush
Velociraptor
Posts: 27
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Post by greybush on Aug 7, 2013 5:04:26 GMT
I will be milling the top, most likely .040" |
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Post by trenchy on Aug 7, 2013 12:26:39 GMT
ta guys, so im having the block becked already, but i was wondering if there was anything else? Do the wrist pins fit straqight onto the bandits conrods? etc?
The other downside of using busa slugs is that they are always down the bore slightly when at TDC, so the squish "band" is prettymuch ruined, which can also affect off-boost performance quite badly -Does the block decking help with this?
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Post by katana on Aug 7, 2013 18:05:11 GMT
ta guys, so im having the block becked already, but i was wondering if there was anything else? Do the wrist pins fit straqight onto the bandits conrods? etc? The other downside of using busa slugs is that they are always down the bore slightly when at TDC, so the squish "band" is prettymuch ruined, which can also affect off-boost performance quite badly -Does the block decking help with this? Wrist Pins - as long as you use the earlier pistons - both Bandit / GSXR / Busa use 20mm pins Decking - Reducing the block height will effectively 'raise' the piston height - just have to ensure the valve pockets are a) in the right place and b) deep enough for the cam / piston combination. |
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Post by trenchy on Aug 17, 2013 20:38:04 GMT
ok guys. so does anyone have any pics of exactly where to round off and by how much?
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Post by trenchy on Aug 17, 2013 22:43:06 GMT
Ok. now done the sharp edges. I take it the front of the piston is the side with the dot?
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