Almost a 47% increase, to be a little more precise. It does sound a bit far fetched. Not even with an extractor exhaust system. Plus, they are, as you say, double pumpers. Sounds to me, like they'd use a lot more fuel. I would sooner put a couple of Webers on instead. On a Beetle with only a 1776 dual port engine that was statically balanced and CC'd and a c/r of around 8.1:1, my increase in HP with two single throat Webers and an extractor exhaust and a very mild cam for torque not revs made it possible to whip this guy in a Mitsubishi Galant with a 2.0L pushing 142HP. That was without attempting to do so, as I told him about a year later when he saw my Beetle and recognized it from the time my humble Beetle mopped up his Galant. I don't drag from stop signs, but I was in a hurry to get on my way to Fla. that day and I did remember some Mitsubishi next to me breathing hard and really taking off as I turned down a side street. Made me wonder if I had done something to piss him off, or he had a spat with his woman or something. Now, that really exasperated him. That thing (my Beetle) would go over 100mph and get 32mpg doing it. Had to put extra weight in the front for safety. Of course, it wasn't cca/c (closed circuit air conditioning). I had the vents open for air. Sort of like riding a bike without the bugs and road grit from the semi in front of you hitting your arms and getting in your eyes and hair, even with a helmet. But yeah, it was a cage, albeit a happy one... Stanley
________________________________ From: Allen Thomas <[email protected]> To: [email protected] Sent: Sat, August 14, 2010 9:56:24 AM Subject: Re: [Nighthawk Lovers] Anybody want to ditch the CV carbs on their 750 for some racing mikuni flatslides? I also have some other parts that must go! Aldo, I'm a bit skeptical on the 100HP claim. Please educate me. I can't see how changing carburation could net +40% increase. Here is why: both carburator sets are the same diameter so they will flow the same CFM. Even if the slide carbs flowed more CFM, flowing higher CFM only benefits at WOT, so unless the lower CFM carb were seriously undersized would you get any benefit. In fact if the carburator flows a higher CFM than the engine can draw, then you will actually make less power! So taking flow off the table the only benefits of slide carbs over CV are that you can open the venturi faster as it is not depending on vacume to move the slide. This has importance to drag racing; first it allows you do run pods with no ill effect, it also allows you to drop the weight of the airbox, and lastly you can feel if you are opening them at the proper rate (like I said if you're carb flow is higher than engine draw you loose power). You would gain HP by the reduced intake flow of the pods but not over 40%. To get those kind of numbers you would need to cam, change valve springs, and most likely port the head, which would maximize the power output at a higher RPM. Also an ignition advance would be needed which requires a part I have not been able to find. This of course would take away from the drivability of the engine. I can't tell you how many hot rods I have spanked over the years that had a tunnel ram intake with a 750CFM or larger carb on a basically stock small block. Had they known that a dual plane intake with a 600CFM would make them faster they might have had a chance. In car terms what you are doing with slide carbs vs. CV is going from a vacuum secondary to a double pumper. It isn't necessarily an upgrade, it all depends on the setup. On Fri, Aug 13, 2010 at 1:10 AM, Aldo <[email protected]> wrote: I don't know if any of you are interested but I have some racing carbs >that will fit a 1991-2003 NH750 I don't know if the other Nighthawks >have 34mm carbs but maybe they'll fit them too. These are the key to >unlocking some major power in the CB750 motor. It is not for >everyone... 100HP is a big difference from 67.7HP > >They are 34mm Mikuni Flatslide racing carbs just like below: > >http://www.orientexpress.com/Universal+Parts+%252526+Accessories/Intake/Mikuni+-+RS+Flatslide+Carburetors+34mm+-+Fits+Kawasaki+KZ+Models%25252FSuzuki+GS+%252526+Early+GSXR+Models%25252FSet+Of+4%25252FClick+For+Applications.html?osCsid=da7bbeaca788817049b0f4c80f2dfccf > > >If you are interested maybe we can strike a deal... I don't want to >lose too much cash on this but I am not using them so I better sell >'em. > > > >I also have: > >Stock NH750 seat in nice shape. $90 Shipped > >Stock 4 into 2 pipes in nice shape. $100 + shipping > >Stock chain guard in nice shape. $25 Shipped > >Stock mirrors also in nice shape. $25 Shipped > >-- >You received this message because you are subscribed to the Google Groups >"Nighthawk Motorcycle Lovers!" group. >To post to this group, send email to [email protected]. >To unsubscribe from this group, send email to >[email protected]. >For more options, visit this group at >http://groups.google.com/group/nighthawk_lovers?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en. -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
