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If you are going everywhere at those revs, 200miles per tank is pretty good!
 

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yes, but accel will suffer quite a bit. First do the 15t up front and see how that feels, and then decide what you want to do with the back... It might not seem like much, but when you're dealing with as little power as the 250 has, any little change makes a huge difference.
 

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Discussion Starter · #7 ·
whats the best set up for speed and mpg?if i put a slip on and shim the needles will that help if i change my gearing?this is my first bike so im new at this stuff,im a diesel mechanic so gas isnt really my thing unless its a fourwheeler.
 

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whats the best set up for speed and mpg?if i put a slip on and shim the needles will that help if i change my gearing?this is my first bike so im new at this stuff,im a diesel mechanic so gas isnt really my thing unless its a fourwheeler.
I'd say they pretty much work opposite of each other. Are you more interested in acceleration or lower RPM cruising and more MPG?

If you gear up you'll reduce your cruise RPMs and usually increase MPG. Generally you'll drop 500 RPMs with a 1 tooth larger countershaft sprocket. It will usually smooth out your hwy cruising and most of the time improve MPG - but not that much. Countershaft sprockets aren't real expensive, so it's a good way to try it out. You may notice a decrease in maximum acceleration though, as the engine will have to pull harder than before.

What was the affect when you shimmed the needles? If it wasn't a significant improvement you'd be best to drop them back down if you are looking for mileage.
 

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yea, Christian, you're trying to do what can't be done.... You can either have acceleration, or top speed and better fuel efficiency... Unless I misunderstood your reply, at which point I apologize.... Also, at a certain point the bike won't enough power to pull a higher gear ratio to that top speed... You DO need a specific amount of power to pull to a specific top speed... Aerodynamics considered, if you speak with the land speed racers you'll see they all agree. Why? Because F=MA M = mass, and that is a constant, your weight + motorcycle weight. F = force which is also a constant, the amount of power the bike has, which means A = acceleration, and a factor in top speed is also set being that the other 2 factors are set... So, all you're doing is changing the gearing which means that you get to your maximum "A" faster or slower, but it's not changing the value of "A". I hope that makes sense...

Racer X has a TON of stuff on this dispersed all over the boards, I would recommend searching for his posts and threads. I wouldn't tell you to do all this research if it wasn't for the sheer magnitude of posted knowledge on this subject, and if it was a quick and easy answer, I'd just post that, but you're getting into optomizing the bike from a physics standpoint.

In essence, what the argument comes down to is this:

1.) Figure out how much you want to spend.
2.) Within that budget, figure out the best way to get the most power out of the 250
3.) With that power, figure out if you want to use it for fuel efficiency (higher gearing), or faster acceleration (shorter gearing). Since you've stated that mpg's is your goal, obviously that would be higher gearing....

There is another factor I just thought of which you should consider. The power band... The 250 is happiest between 7,000 and 11,000 rpm's in most cases where it produces the most efficient combustion, so don't necessarily gear towards lower RPM's, gear towards getting your engine spinning within that zone on the majority of the time spent riding the bike....

Try the 15T front and see what you think. If you think you can handle less acceleration, then go to a 43T rear sprocket. If you find that you can baby the throttle even more and want to sacrifice even more acceleration, go to a 41T rear sprocket, but I would recommend not going taller than that...

Here is something else: inherent loss in the subsystems of a motorcycle. Oil type and kind, and chain maintenance are the 2 biggest factors here... The easier you can make the rear wheel spin by decreasing internal friction the more power which the engine is generating is getting put on the road. So, if you were to go to a synthetic 0-40 oil, you might see some slight (fractions of an HP) increases... Keep on top of your chain is also a BIG one! Proper alignment and tension can "free up" quite a bit of power, as much as 2hp from a chain which is not maintained to a chain which is perfectly maintained....

On chains: a standard non-o/x ring chain has less inherent resistance, being that it has no rubber pieces scrubbing off power, but they stretch A LOT. I'm talking a chain adjust/clean/lube EVERY 50miles... So they are good or racing, but NOT for road use. However, if you want to play with that, feel free... I hope this gives you a broader frame of reference to understand this stuff with...
 

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Discussion Starter · #10 ·
i think im going to try a 16t front and just stick with that,ive had a few buddies tell me they make a 17t and that would be best but idk.i want to go faster,not take off but top end,im scared im gonna end up blowing my motor do to high rpms so i always ride at about 6-8 grand.i always maintain my bike after every ride,i give it a bath and lube up every moving part but im do for a oil change and im wanting to do syn oil but i dont know what kind to use.thanks so much for all the help
 

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i think im going to try a 16t front and just stick with that,ive had a few buddies tell me they make a 17t and that would be best but idk.i want to go faster,not take off but top end,im scared im gonna end up blowing my motor do to high rpms so i always ride at about 6-8 grand.i always maintain my bike after every ride,i give it a bath and lube up every moving part but im do for a oil change and im wanting to do syn oil but i dont know what kind to use.thanks so much for all the help
What is the current top speed and at what RPM? If you are running out of revs (at redline) gearing up might give you more speed. If not, you aren't going to get any more. But gearing up significantly will make day to day city riding a pain and make acceleration painfully slow.

A good inexpensive synthetic oil is Shell Rotella T6 5W-40. Better would be Mobil 1 4T Racing 10W-40 or Castrol 4T 10W-40. Best would be an Ester-based full-synthetic like Motul or Repsol.


Jay
 

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Christian, FYI - the 16T requires modification of the front sprocket cover to fit, so a 17T would require so much material to be removed from the cover that there would be no point in keeping it... If you just want a bolt on, go with a 15T. If you don't mind cutting a bit out of the cover, go with a 16T. Quite a few have done the 16T with great success!
 

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jkv the top speed is 100mph at 10500 to 11 grand and i just want it to go about 120 so when im at 80 its only at about 8 grand and ill try the 16t ill get my ninja buddies to help me with the cutting.
If you are looking to go 120 mph, you may want to look at what Racer X
had to do to get 121 mph. http://www.newninja.com/forums/f98/modifications-list-3620-41.html[url]http://www.newninja.com/forums/f98/modifications-list-3620-41.html[/URL]

If you are looking to cruise at 80 mph(actual) @ 8k rpm here is the sprocket set up you would need
14/38 @ 8k= 76.9 mph (actual speed)
15/38 @ 8k= 82.4 mph (actual speed)
16/41 @ 8k= 81.5 mph (actual speed)

The down side to the 15/38 or 14/38 setups is you need to shorten the chain to 104 links. The stock chain is too long. Also the bike needs to be tuned to ensure you have enough umph! to maintain that rpm speed. Hills could present a slight problem and downshifting would be necessary for the 15/38. Hwy cruising is smoothed out a lot.

A 16/41 setup will present you with a slightly slower take off, but again the bike needs to be tuned to ensure you have enough umph! to maintain that rpm speed and enough power on the top end for a little more acceleration. Hills could present a slight problem and downshifting would be necessary. Changing the chain is not necessary.

An ideal setup would be a 15/42 or 41. 15/41 will get you 76.4 mph (actual) @ 8k rpm. With minor tuning such as shimming and removing the snorkel you should have no problem with acceleration or pulling past 9k in 6th gear. no shortening of the chain is necessary. For most this setup presents the right balance between acceleration and top end speed.
Providing you can reach 11500 rpms in 6th gear, your top speed would be approx 109.8 mph (actual) & 110 mph with a 14/38
 

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Discussion Starter · #15 ·
well the hills would be no problem cause i live in florida in the glades so we dont have big hills or windy roads so its all flat ground =) but im deff gonna try a 16t in the front first before i change the rear to see how i like it.
 

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Looks like Blue Ghost has your gearing options covered for you!

Try the 16T countershaft and see what you think.

As Racer X noted, no gearing combo will get you to 120 without some additional power. It's not easy to get to that speed with a 250 Ninja, but it can be done with enough work.

Get it geared so it gives you a smooth cruise but is still reasonable in town, unless you plan to use it as a race bike it needs to be a balance of both IMO.


Jay
 

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Discussion Starter · #20 ·
today i tolk the snorkel tube off and modded my stock muffler and i got a little more power,next im going to put new e3 plugs and run some marvel mystery oil in it.i love this bike.but im going to buy a new 1 in jan a zx-14 and give this bike to my girl.
 
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