June 8th, 2011, 02:42 PM | #41 |
ninjette.org member
Name: John
Location: Los Alamitos
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at 15/41 my rpm to speed is 1000:10mph.
So running 8500rpm at 85mph on the speedometer. Saves me alot on gas for freeway travel.
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2010 Ninja 250r Special Edition Blk/Red, Pazzo controls, Lowering kit, Roaring Boyz Toyz risers, Corbin seat, Shogun frame sliders, Yoshimura Full Exhaust 2008 Suzuki GSXR 600 Silver/White |
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June 8th, 2011, 02:44 PM | #42 |
ninjette.org member
Name: Tony
Location: Surrey UK
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Move to the UK, our gallons are bigger ....
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June 8th, 2011, 04:44 PM | #43 |
ninjette.org dude
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June 8th, 2011, 11:43 PM | #44 |
ratlab
Name: reese
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a tight chain won't wear out suspension but won't allow the rear shock to do it's job-it won't allow full stroke -dangerous
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June 8th, 2011, 11:46 PM | #45 |
ninjette.org member
Name: Tony
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A tight chain will also put extra pressure on the bearings .......
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June 9th, 2011, 02:27 PM | #46 |
ninjette.org member
Name: Tony
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So, taking a look at the sprockets on my rat, and finding that I'm glad I did, the PO hadn't bolted two of the nuts up, they were close to the end of the studs and could have caught on something
The PO had put a new 'O' ring chain and sprocket set on, all looks good quality, but the sprockets were 13/39. I did some maths, and just by dividing the bigger by the smaller I came up with this : 14 / 45 = 3.2 14 / 43 = 3.07 15 / 45 = 3 13 / 39 = 3 15 / 43 = 2.86 |
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June 9th, 2011, 04:00 PM | #47 |
ninjette.org dude
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Yup - looks like you had the same ratio as the much more common 15/45 that many people land on with a ninjette. Glad you caught the loose nuts!
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June 9th, 2011, 05:29 PM | #48 | |
ninjette.org sage
Name: john
Location: Palm Beach County, Fl Sligo County, Eire
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Quote:
Last futzed with by coondog; June 10th, 2011 at 07:09 AM. |
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June 9th, 2011, 06:03 PM | #49 |
ninjette.org sage
Name: Luke
Location: Sevierville, TN
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So is there an agreement out that says 15/43 is the best for MPG and rpm as a cruiser?
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June 9th, 2011, 10:33 PM | #50 |
ninjette.org dude
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There is no best. Choose what you like, and if you don't like it, tweak it until you do.
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June 10th, 2011, 07:24 AM | #51 |
ninjette.org sage
Name: john
Location: Palm Beach County, Fl Sligo County, Eire
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Just looking at the last two posts means there would be divergent opinions, strong ones. Flatlands of Tennessee vs. altitude and hills of S.F. lets just assume. Personally I'm surprised Alex is so open minded but that's because i'm so close minded. Where i am and say Texans (FLAT FLAT FLAT) if you're into gas mileage and commute long distances go 15/41, help yourself. Just be happy with keeping the speed limit, and that should work into your "savings" plan anyway so you're set. I don't give a hoot about cost of gas or mileage, although this ethanol sh*t I'll listen to anyone. I also like 6th gear alot, and mods get you there with the mid range boot as well as 15/45 gearing (15/44). Everyone is doing what they're doing hopefully for the "specialty" they desire. I like to use all my gears to there maximum, don't give a hoot, and love 11k rpm = 90mph. We're as different as the gear we wear but ONE as cyclists regardless of reason. Yes Alex I was called to the Window.
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June 10th, 2011, 07:50 AM | #52 |
ninjette.org certified postwhore
Name: Frugal
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WRT gearing, acceleration is determined by the relationship of engine RPM to rear wheel RPM, or speed. So, if your engine is turning 8,800 RPM at 50 MPH the instantaneous acceleration will be the same regardless of what the various gear and sprocket ratios are between the crank and the rear axle.
Having taller gearing on the sprockets and downshifting more to get the RPMs where they were before means roughly the same acceleration. One thing that does change is the rate of RPM change per speed change. Taller sprockets mean that you spend more time in each gear before upshifting. Short version? Down shift more, accelerate about the same as before, enjoy the lower cruising RPMs. |
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June 15th, 2011, 07:42 AM | #53 | |
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This is my post from the mpg thread. I figured it belongs here too.
Quote:
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June 15th, 2011, 09:20 AM | #54 |
ninjette.org member
Name: ___
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I topped off my '04 yesterday and recorded 61.4mpg with the 15T sprocket. It's a keeper!
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June 15th, 2011, 01:23 PM | #55 |
KThanksBye
Name: Kevin
Location: Orange County
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Alex I remember you saying in another thread that the 15t wont raise gas millage? Can you comment on that?
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June 15th, 2011, 02:24 PM | #56 |
ninjette.org dude
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Yeah, I don't believe the posts. Over time, if people continue to ride the same way they did prior, the difference will be negligible. If someone is trying to maximize mpg on the first tank after the switch, perhaps the initial jump looks more sizable. The bike just isn't that much more efficient making the same required hp at 8500 rpm compared to 9000 rpm. If it's a percent or two it's alot. Reports of 20% improvement simply cannot be attributed to the change; it's either a misrepresentation of true mpg, or the riding style changed drastically before/after the swap.
I could get down into the 30's mpg just as easily with a 15-tooth front as with the 14-tooth front on our pre-gen, it's all about how you choose to use the throttle.
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June 15th, 2011, 03:40 PM | #57 |
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I keep detailed records of fuel mileage, and my 10-tank average went from 59.8 to 62.6 with the change, same commute and similar weather. Though your reasoning is correct, it doesn't take into account motor efficiency, more specifically, pumping losses. Gasoline engines suck air in past a restriction in the form of a throttle plate, and it consumes energy to do so. The general rule of thumb is that you burn less fuel for a given power output at lower RPMs and more open throttle. It's referred to as Brake Specific Fuel Consumption. Now, there are a lot of other variables involved, so lugging a Ninja engine like a low-end torque motor will not yield better efficiency, but the minor change in RPM with the 15T sprocket does help. The secondary benefit, at least for me, was the elimination of oil consumption at extended highway speed traveling.
As a side note, one of the reasons diesels have such better efficiency is that they don't have throttle plates, just a gaping hole with an air filter. |
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June 15th, 2011, 04:05 PM | #58 |
ninjette.org dude
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The key word here is slightly. The fuel consumption is much more closely related to the hp being produced by the motor, than the rpms used to produce that same hp. Yes there are pumping losses to consider, but a 1/15 change in revs just isn't going to be particularly significant. The differences in pumping losses are measurable when you are talking about cutting revs by a 1/3rd or more. Keeping the revs below a certain threshold on the pre-gens can be critically important for the oil consumption reason you point out, and that is reason enough to gear the bike a bit taller if one puts on significant highway miles.
Keep track of the next 10 tanks and see if it remains over 62 or dips below 59. Whether it does or not, attributing it solely to the sprocket change is really hard to do, even if one does their best to ride in exactly the same manner and in the exact same conditions. I do not disagree that over time one could determine it provides a very small uplift, but anything more than a mpg or two has less to do with the gearing change than all of the other factors that need to be taken into account. For some unrelated yet still interesting reading, check out how BMW no longer uses throttle plates on their engines in the conventional sense, and relies solely on controlling valve lift directly. http://en.wikipedia.org/wiki/Valvetronic
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June 16th, 2011, 07:34 AM | #59 | |
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Quote:
I don't question the validity of my data, and my long-term documented observations back up my conclusions on mileage increase with the 15T. Parting observation: My mileage hasn't gone below 60 mpg since I installed the 15T sprocket. |
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June 16th, 2011, 10:48 AM | #60 |
ninjette.org dude
Name: 1 guess :-)
Location: SF Bay Area
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The consensus on the forums is that it increases acceleration, improves fuel mileage, makes the bike 3.6 times more comfortable on the highway, and causes male pattern baldness to reverse. Its benefits are universally overstated. I appreciate that you are getting some great mileage on the bike, and it's gone up a few percentage points since you changed the sprocket, and I'm glad it's working out for you. Others don't see the same (or any) mileage benefit and are surprised at that fact, thinking that the sprocket change itself is a guaranteed significant uplift in economy.
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June 16th, 2011, 02:53 PM | #61 | |
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Quote:
Time to do a survey... |
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June 20th, 2011, 01:54 PM | #62 |
ninjette.org sage
Name: john
Location: Palm Beach County, Fl Sligo County, Eire
Join Date: Dec 2010 Motorcycle(s): 2005 ninja 250 street fighter, 2008 street fighter ninja 500, 2001 nsr 125 Posts: 812
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Been waiting for FrugleBugle to quiet down and put his charts away. I could say you're a bore but I won't, but you ARE wrong. Alex reminded me of driving long distances and no matter if we "averaged" 90mph or 55mph, as CrashDenver sang "by the end of the day another 500 miles is done." I don't want to chat, though in a chatroom (I do know that much) because I don't think anyone can figure it, even with all the obvious reasons to come up with. For ME, 500 miles a day avg. is always bottom line and it's a freak of nature in my life.
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June 27th, 2011, 10:34 PM | #63 |
ninjette.org member
Name: jayvee
Location: marikina, philippines
Join Date: Oct 2009 Motorcycle(s): ninja250r 2009model Posts: 30
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what do u think on this
hello sir just a newbies question, did anyone try to used a 15teeth front and 47teeth rear...what do u think will happen if u have a set of sprocket like this...how will be the performance, fast start or fast top end?...
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June 27th, 2011, 10:46 PM | #64 |
ninjette.org dude
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What would be the point? It's so close to the stock 14/45 ratio that it would change almost nothing.
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June 28th, 2011, 07:07 PM | #65 |
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June 29th, 2011, 08:11 AM | #66 |
Smoker
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Location: SoCal
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The one thing I've found that has a direct and significant impact on MPG is how you ride. If you short shift and keep it under or at the speed limit, you will easily and consistently be in the high 50s / low 60s if not more. But I've still seen a jump in my MPG after the change. Maybe because I don't (have to) spend so much time at the upper limit of the rev range.
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June 29th, 2011, 10:22 AM | #67 |
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