How Low Can I Gear And Still Do 200 Mph?

Discussion in 'Gen II Busa Information' started by Mythos, Sep 9, 2017.


  1. Mythos

    Mythos Registered

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    I've been happy with it for almost ten years now and it wheelies easy enough in first gear but I wouldn't mind a little more strength at low speed in first gear and especially 6th which I almost feel like I don't need at legal speed limits. BUT I dream about doing 200 mph on this bike. Should I stick with stock gearing or can I go up a few in back? Also plan on turbo someday and possibly still be on the sprockets and chain I'm changing in now. I will be using ECU Editor soon and I can raise my rev limit so that would help with lower gearing if I don't mind running my engine to 12500 rpm (which I'm not real sure about either).
     
  2. Boomer07

    Boomer07 Registered

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    I claim minimal expertise on this other than what I've seen from others and a conversation I had with Frank at Powerhouse. Stock gearing won't get you to 200, you'd need to drop teeth in the rear or add a tooth in the front, possibly both. Stock should top out around 195 in a perfect scenario. I'm +2 in the rear currently with the ECU flash from Frank and while it gave me more grunt, he concurred that 200 wouldn't be possible. Also, turbo bikes tend to need the higher gears as well or they wind up too quickly with all of the extra power. I'm sure someone will chime in who knows more than I do, but I believe I'm fairly accurate. Good luck with your pursuit!
     
  3. Hayabusa Wannabe

    Hayabusa Wannabe Registered

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    Here is a theoretical calculator to use in conjunction with solid advice. Note: Select GSX even though the Busa is designated GSX-R:

    http://www.gearingcommander.com/
     
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  4. Mythos

    Mythos Registered

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    Opinions based on theory and experience are both helpful but most of the time they are not quite the same thing.

    That sounds reasonable. I have gone close to 180 on my 14 with +4 teeth on the rear and a (well worn) 200/55 tire. I was about 500 rpm away from bumping the rev limiter. Realistically, I don't think I could have quite gotten 190 mph with gearing that low. It sure did pull hard all the way though!

    Gearing Commander is claiming the max possible rpm to be 10.5 k rpm. I see my tac go to 11,500 right now. Is the tac off by that much or is Gearing Commander wrong?

    If I raise my rev limit to 12.5k, hopefully I can get at least a true 11,500 rpm. With that extra rev limit, Gearing Commander says I can do 201 mph--theoretically speaking.

    but if that were true in the real world, everyone would be enjoying the quicker revs of shorter gearing and still doing 200 mph.

    SO what do you think the bike would REALLY do with a 47 tooth and 200/60 rear tire (if that will even fit in the swing arm)?
    gErng.cumandr.+4:200:60.png
     
  5. michael parris heuberger

    michael parris heuberger Registered

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    HI. I will be running 20 front & 36 or 38 rear and maybe a 200/55 rear tire for top end, for drag racing I will run 19 front & 42 to 44 rear & a 200/50 tire. The bike is with a built motor & RCC super ultra turbo turned by Powerhouse!
     
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  6. 04LE

    04LE Registered

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    i went -1 front and -1 rear. If I ever get to a land speed event where i want to do 200 i can swap the front out for the stock one and be able (theoretically) to do 200. That was enough of a wake up for me (for now).
     
  7. fallenarch

    fallenarch I made fun of the panties, now I have them :( Registered

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    First of all not many people are going 200 regularly. If you are doing an LSR event its easy enough to change the gearing. Around town with a N/A engine up 2-3 in the back is nice. I did go up 4 once but did not find this to be a good ratio for ridability or gas mileage. The tach should pretty accurate but there is no need to exceed 11,500. That is safe for the engine and hitting 11,500 in 6th is very fast. More likely you'll run out of steam first. All opinion, I don't visit that territory at all.
     
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  8. Mythos

    Mythos Registered

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    I think the tac is pretty accurate. Gearing Commander probably just reports a thousand rpm short of the normal rev limiter by default to be on the safe side. They do the same thing with the ZX-14, I noticed. You can put whatever max rpm you want in the table.

    The LSR gearing sounds like it would be a dog on the street. I could see using the drag racing gearing on the street no problem. Both of your setups are less aggressive than stock. Interesting. I can see less aggressive than stock being effective for drag launches.

    That sounds like a good idea. It would be a lot easier to just change the rear but you might run out of axle slot if you went with such a small rear sprocket.

    Yeah, I guess you're right. It's impossible to make a gearing choice that will be best for every situation. I went +4 on the rear with my Gen1 ZX-14 and to tell you the truth, the change was just about right. It was not dangerous and the bike is more snappy although I must admit, it's roughly the same feeling as downshifting a gear---so you have to ask yourself if it's really worth doing because it does suck gas.

    Seems to me the primary gearing of the busa must be milder than on the 14 because the stock sprocket gearing is much more agressive than what the 14 has. Stock for the ZX-14 is only 17/41. A 45T is not crazy on the 14. Generally speaking, the engine runs about 500 rpm faster at speeds I do most regularly. I don't know why people bother with 17/43 on a ZX-14--that's like nothing! I wonder how much differently the busa will respond to +4 on the rear than the 14 did? Any ideas on that?
     
  9. RansomT

    RansomT Registered

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    Realistically, a piped stock Gen 2 Busa will have a very difficult time reaching 200 mph without help from mother-nature. Tuning the bike with MR12 and lowering it, gearing it 18/41, gives you chance after practice. Raising the rev limiter above 11,400-11,500 will do no good, the bike will just fall on it's face much above 11,200.

    Yes, tachs are off. Gen 2s by 200-300 hundred up high. Speedos are really off. Stock gearing 7% and as you change the gearing, even more. Gearing Commander also can be off due to tire slip, yes folks above 170 mph the rear tire starts to spin due to frontal forces.
     
  10. michael parris heuberger

    michael parris heuberger Registered

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  11. michael parris heuberger

    michael parris heuberger Registered

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    Hi. the bike will be set up for more than 200 mph in the 1/4 mile. hopefully more than 600 hp to the ground!
     
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  12. Dennis

    Dennis Registered

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    Gen 2 tachs are off more like 400-500 rpms. Even at mid rpm ranges. Speedos are off too, the faster you go the greater the % error.
     
  13. Mythos

    Mythos Registered

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    MY GOD! That's the bike I want!

    All this 200 mph stuff is just leading me to go with what I think I'll like for most of my riding. Like someone else said, how often do you go 200 mph or even try for that matter? I probably only try to beat my illegal speed limit record once every two years.

    If I stick with an 18 T front and go to a 47 tooth rear, it looks like I can keep the stock chain length. I doubt if I will need anything more aggressive than that gearing and if I do, I can just go down a tooth in front and maybe even go up another in back all without needing to lengthen the chain. If I find I can't get the bike to go fast enough for my speed runs, I guess I will have to worry about what to do with gearing and chain at that time. Seems like I could gear quite a bit higher or lower than stock with the same stock length chain. Sprockets are nothing but needing to change the chain to accommodate sprocket sizes would be a real PITA.
     
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  14. sixpack577

    sixpack577 Top Gun Registered

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    Buy a +3/46t rear(or a -1/17t front) for a nice bump in low end power.
    Buy a -2/41t rear for a 200-202mph capable top speed.
    Swap sprockets with a tire change.
    All these fit the stock length chain, and have room for adjustment.
    You will need to remove the mirrors to break 200mph too
     
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  15. ROADTOAD1340

    ROADTOAD1340 Registered

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    Going to try sixpak's recommended gearing , the 17 t front . Maybe even plus 1 rear also . Going to test with current 530 set up , then change to 520 DID . Not for 200 mph obviously , but punchier stomp throughout rev range , for my stock motor . I do currently run a Bridgestone RS10 200/55 on 6.25 " rim , and I may in future run a Pirelli SC2 v2 200/60 and SC1 or 2 front . Currently run 18t / 44t because of rear tire .
    We have a salt lake top speed event in OZ , Lake Gairdner Speed Week , and some years ago a Gen 1 busa stock , with gearing ran just over 200 mph . The same fellow ran 203 mph on a stock Gen 2 with gearing . My mate now owns that Gen 2 . The Gen 1 is more aerodynamic than Gen 2 according to those in the know . I have been told also to keep the front sprocket as large as possible for chain , for you pilots wanting taller gearing , but I think the 17 t on front for me on street will be okay .
     
  16. michael parris heuberger

    michael parris heuberger Registered

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    Well It will be for sale. The people I am working with have gone 6.46 sec at 227 mph in the 1/4. The turbo guys at RCC and Powerhouse have gone over 250 mph. So with gear changes and the right built turbo motor and tune you can do it too. GINBRET has a bike for sale on the ORG for $20,000.00 and that is a deal for that bike! Because mine will be between $60,000.00 to $80,000.00 GINBRET has about $50,000.00 in his.
     
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  17. Mythos

    Mythos Registered

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    Good idea but I think I need +4 on the rear. I love the look of a bigger rear sprocket too. 18 front, 41 rear for top speed and we'll see where we need to go from there.

    Mirrors have been gone for years. Good weightloss and looks so much better on any bike IMHO.

    I saw a 525 conversion kit by Vortex. That's a big reduction in rotating mass. I was persuaded NOT to go smaller on pitch than stock 530 with my ZX-14 and the busa makes even more torque (a few foot lb is significant, I can tell by riding/wheelying the two bikes back to back). Aren't you concerned about snapping a chain going down to 520??


    Highly recommend!!!!!! Have ourchased 3 sets of Supercorsas and that is the one tire I have tried that makes a noticeable difference. Not to go tire thread here but I have also used Diablo Superbike Pro slicks on the street and had no issues, loved the sharp handling of the 200/55. 200/60 isn't going to fit the 14's swingarm but good to know it will on the busa. The Pirelli slicks were cheaper than DOT tires!...I believe they discontinued the superbike Pros which is very unfortunate. I am pretty sure it was the same compounds as the Supercorsa, just no sipes. Dunlop makes a similar slick for low temps and fast warm up. I plan to give these a try in the near future.

    That's my dream. If I had 20k, I'd be looking at that bike and putting the orange 08 up for sale...or maybe keep both a while. I really want to build my own but DAMN, $60K? I really can't see that. 250 mph that's GD crazy! 200 in a quarter is good enough for me. Nobody's going to see you in 6 seconds over a quarter mile. LOL I was messing my pants waiting for the GPS calibrated needle to hit 180 and I was on it for a mile and about 18 seconds I think. Too much of a chance you could have unwelcome observers spending all that time in hyperspace.
     
  18. ROADTOAD1340

    ROADTOAD1340 Registered

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    With stock HP and torque , and even some , the 520 DID ERV should be fine . I have read on this forum from a track Guru (Tuff Busa) sorry if wrong fellow , that that chain has the huge strength ( industry standard super race chain ), but also know first hand about some road race bikes here in OZ , pumping out near 150 ftlb of rear wheel torque with similar HP as Gen2 , with no dramas running this chain . The chain may need more inspection / adjustment , but I can cope with that . You monster HP and Torque pilots , well I'm guessing you won't be changing to 520 , and go with what you know . I am going to try it out in a while , once gearing combination sorted .
     
  19. busafan08

    busafan08 Registered

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    I have read here that 19/43 gearing with a few mods is a good combo also to reach 200 mph ? :thumbsup:
     
  20. Mythos

    Mythos Registered

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    That might do it but it will be a little less lively at lower rpm and I could already use some livening up. I'd rather leave front 18 and see what I could do with the rear because the rear is so much easier to change.
     

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