demon Posted April 26, 2004 Share Posted April 26, 2004 While I was under the tank this weekend messing with the pair valve, I was looking over everything making sure my baby was right. I noticed somethin very strange. The velocity stacks are quite a bit smaller than the throttle bodies. Won't this restrict flow? Anybody "opened em up" to the dia. of the throttles, or know of anyone who makes larger ones that let the throttle bodies flow what they should? I think it would be worth a few HP on top end when added with a full exhaust system and proper PC map. Quote Link to comment Share on other sites More sharing options...
Northman Posted April 26, 2004 Share Posted April 26, 2004 I don't think anyone makes larger ones for the XX. I know they're available for the Busa & the 12, but not the XX. I'm working on enlarging mine right now, but won't know for another couple of weeks if it can be done, or will be. Quote Link to comment Share on other sites More sharing options...
The Krypt Keeper Posted April 26, 2004 Share Posted April 26, 2004 Buddy of mine changed them on his GXSR 1000, he went with the 750's stacks. I don't know why but he said alot of people on gixxer.com did it. Heres some info he posted about it after he got her Dyno Tuned HP: 165.4 @ 12,250rpm TQ: 83.0 @ 8,500 rpm Bike: 2003 GSX-R 1000 7k miles break in method- babied it like crazy Power mods: Arata full exhaust PCIII USB 750 short velocity stacks Denso Iridium spark plugs pair mod Quote Link to comment Share on other sites More sharing options...
Violent J Posted April 26, 2004 Share Posted April 26, 2004 I'm not sure but if the 750 stacks are smaller, it would give his 1000 more midrange because the smaller stacks would create more velocity. It would hurt the peak HP though. But maybe the 750 stacks are bigger. Anybody know? Quote Link to comment Share on other sites More sharing options...
Northman Posted April 27, 2004 Share Posted April 27, 2004 He advertises "GSX-R750 short stacks" To me, that implies they are shorter than the 1K stacks, which would give more top end. You'd have to see back to back dyno charts to see the difference, though. Quote Link to comment Share on other sites More sharing options...
demon Posted April 27, 2004 Author Share Posted April 27, 2004 anybody know the throttle body spacing on a 954? Factory makes some stacks that fit the 954 but none for the xx as of yet Quote Link to comment Share on other sites More sharing options...
DaveK Posted April 27, 2004 Share Posted April 27, 2004 We should check with Harry on this one :wink: Quote Link to comment Share on other sites More sharing options...
Northman Posted April 27, 2004 Share Posted April 27, 2004 Fuck, I never thought of that. Geez, Dave. I'm sorry. Where was my head there? :banghead: Quote Link to comment Share on other sites More sharing options...
EVLXX Posted April 27, 2004 Share Posted April 27, 2004 I'm working on enlarging mine right now, but won't know for another couple of weeks if it can be done, or will be. Very interesting.... will you please post your findings when/if you get it done. Thanks. Quote Link to comment Share on other sites More sharing options...
The Krypt Keeper Posted April 27, 2004 Share Posted April 27, 2004 What about a K&N filter? I have heard stuff from both sides of it.. Some say to stay stock, some say the K&N is better, while others say get the K&N and use is since you can keep it forever from cleaning it over and over. Would this more free flowing air, with some bigger stacks help out the midrange? Quote Link to comment Share on other sites More sharing options...
tomek Posted April 28, 2004 Share Posted April 28, 2004 What do you mean by size?You could change the height of velocity stacks but size ? I.D.`s at the bottom and top and lenght of V.S. are corelated (certain deg. taper ),you can`t just put bigger pieces on given throttle bodies.Bigger bodies would call for increse of I.D. of velocity stocks. XX has 42 mm throttle bodies,so has Gixxer 1000.In AMA racing they have to use stock pieces yet it is not stoping Suzuki from blowing everybody else.Mladin bikes makes about 180 rwhp,therefore increasing size of throttle bodies would be last on my list if I were to build motor. BTW I rode Gixxer 1000 with parts from 750,it may make higher peak number but powerband was nothing to be impressed about.Motor was soft in 8-9k rpm range. Engine tunning is slightly more sophisticated then putting bigger this and that. Quote Link to comment Share on other sites More sharing options...
Northman Posted April 28, 2004 Share Posted April 28, 2004 XX has 42 mm throttle bodies,so has Gixxer 1000.In AMA racing they have to use stock pieces yet it is not stoping Suzuki from blowing everybody else.Mladin bikes makes about 180 rwhp,therefore increasing size of throttle bodies would be last on my list if I were to build motor.) Mine will have more power than that, so will need more air. Like I said, it's something we're looking into. The velocity stacks don't exactly blend well into the throttle bodies, and the throttle bodies don't blend well into themselves, either. It's more about smoothing out the flow, than just enlarging everything. The purpose of the velocity stacks is to straighten & smooth the incoming charge, which results in more airflow. Quote Link to comment Share on other sites More sharing options...
demon Posted April 28, 2004 Author Share Posted April 28, 2004 What I don't get is why the velocity stacks are a smaller ID than the throttle bodies. The velocity stacks look to be 1-1.5mm smaller than the 42mm throttle bodies. On most GSXR's I've seen, the velocity stacks are the same size as the throttle bodies. The smaller diameter stacks are a problem with Honda 929,954, and 1100's from what I have researched. The smaller diameter would work better with a carbed bike, increasing air velocity to pick up fuel better, but a FI bike doesn't need this since the fuel is injected rather than sucked through jets. The height "tunes" the throttle bodies: short=high RPM Horsepower, long=low RPM Torque. In AMA Superbike when they allowed the 1000cc 4's to compete, they REQUIRED them to run stock intake parts to equalize power production between them and the twins. If they wern't forced to, how many stock intake setups do you really think you'd see? They had some pretty exotic shit on the 750's. Since most of us don't compete in superbike with our birds, We can change stuff around. The stock setup is a compromise with HP, Torque, fuel economy, and NOISE. Since most of us put free flowing exhaust on our bikes, why not help the intake system out? Quote Link to comment Share on other sites More sharing options...
pace Posted April 28, 2004 Share Posted April 28, 2004 In the car world, we would see significant/measurable gains from porting and smoothing the TB interfaces. I would guess this is a worthwhile modification after you've realized the easy gains elsewhere, even on a carb'd bird. -Pace Quote Link to comment Share on other sites More sharing options...
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