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Old June 15th, 2020, 11:51 PM   #1
nunia720
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Advice on cheap, like free Mods-for quicker acceleration~~Yes I searched !!!!

Hello All!!! New 2 forum but I would lurk when looking for answers on general maintenance kind of stuff. Appreciate the wealth of info on this site, seriously. Thank you everyone for the sharing.

Anyways, I have a 2002 and the first performance mod I've done was today, Zip tie on throttle cable. Love it so far. While doing that I pulled out the snorkel and air cleaner to see if sound and performance improved. I do like the sound but am unsure if it is advisable long term or if it does effect performance as I only drove for a few blocks. So suggestions on that would be awesome.

I am also considering the shimming of needles w/ washers. Pretty straight forward from what I can tell but I am looking for real world opinions from riders that have the same model as me. The DIY is in the 08-section, and while I do know it's the same principle I really am looking for opinions. It would be more than appreciated.

And while I do have your ear, (or eye rather hopefully) one last thing I'm wondering about is the infamous sprocket change. Again, I am looking for quicker take off w/out losing too much top speed as I do drive the interstate. I just want to get to the 100 or so miles and hour as fast as mechanically possible. I really do not care about mileage at all. Cost is the biggest concern.

Just a FYI, I usually ride with the Harley crowd, my roommate has a Sporster and we do all of our own maintenance and repairs when doable. As a matter of fact I just replaced the clutch on a friends 2004 Sportster 1200 after the "grenade plate" did indeed detonate. So I like to think I am a little bit mechanically inclined. And before those of you that are familiar ask, YES....we went with the extra plate kit from Barnette to eliminate that stupid design.

Any and all help~suggestions would be more than appreciated. If you would like me to document/record anything recommended that I decide to do I have absolutely no problem doing so. I would of done that w/the Zip tie but the OP covered all bases!!!! Again thanks!!!!

I do apologize for the long post so I will add this to hopefully get you all 2 smile a little.......I did mention I ride with the Harley crowd right? So picture this if you can......me on my little bright ass yellow stock 2002 Ninja250 Beast somewhere in the line of anywhere between 3-10 hardcore Harley riders. Sometimes leading even......but more often than not bringing up the rear so I can cover for the Outlaws that have no tag or license~~~Lol!! Moral of the story is.....2 wheels are 2 wheels, we are all brothers and sisters!!!
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Old June 16th, 2020, 06:03 AM   #2
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You want an air cleaner of some kind. I think we went with a UNI filter in the airbox. Removing the snorkel makes it louder, but also messes with the low-end fuelling and acceleration.

Altering and fine-tuning your jetting will give you snappier throttle response and maximum power.

Adding a quality exhaust system can add power, but some will shift the power peak upward and reduce low and mid-range torque.

You can't have both better acceleration and calmer cruising on the hwy. Gearing down (smaller front sprocket or larger rear) will increase acceleration but add RPMs.

Gearing up (larger countershaft sprocket or smaller rear) will calm the cruising but reduce acceleration.

Stock gearing is a compromise.

Danno will probably chime-in with some specific info on power-mods. He has done dyno testing with jetting and aftermarket pipes for max power.
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Old June 16th, 2020, 09:15 AM   #3
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Old June 16th, 2020, 09:23 AM   #4
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Yeah, it's all balanced and you can't have one without other type of thing. If you do sprocket change for more low-end take-off speed, you'll be revving more on highway and have lower top-speed. Current top-speed is ~100mph at close to redline. If you go with lower gearing, you'll have lower top-speed.

These pre-gen bikes are already tuned pretty darn good for peak-power, tuning for more power won't get you much on top of that. While new-gens can get ~20-22% more power with full-exhaust upgrade, pre-gens will only get about 1/2 of that since they're already in higher state of tune. https://www.ninjette.org/forums/showthread.php?t=13852

Only way to get significant power-increases is to swap in EX500 engine. Best bang-for-buck effort and gets you faster bike than new Ninja 400. Roughly double your existing power. No other bolt-on mod will give that kind of improvement. Not even going all-out on engine-build with big-bore pistons and high-compression will get you double power.
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Old June 18th, 2020, 11:24 AM   #5
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Speed costs money. There is nothing cheap or free you can do to your Ninja 250 to make a huge difference in performance. Just keep it in good tune, valves adjusted, ect... and accept it for what it is , a great little bike.

Just find some nice twisty roads where you can leave your Harley friends behind.

(and I have 3 Harley's and a Ninja 250 in my garage)
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Old June 18th, 2020, 02:41 PM   #6
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heh, heh... Harleys can go as fast as prudent or practical on public roads...
Adding throttle AND lean may not be safe...

Link to original page on YouTube.

Here's some threads on how to bump power on 250:
https://www.ninjette.org/forums/showthread.php?t=257420
https://www.ninjette.org/forums/showthread.php?t=187321
https://www.ninjette.org/forums/showthread.php?t=263401
https://www.ninjette.org/forums/showthread.php?t=89190 (I believe this bike & engine is for sale)

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Old June 18th, 2020, 06:19 PM   #7
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I geared mine for the quicker acceleration. I think that I went with a 14 tooth up front, and a 47 tooth on the rear ( like the ZZR250) -you need a longer chain 520-108.

I documented it in one of my posts...

Take a look at this write up
https://faq.ninja250.org/wiki/I_want...nge_my_gearing


Also, go with "smaller" tires. Stick with stock size - not the "plus" size. E.G. 120 width, not 130, and same sidewall...
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Old June 20th, 2020, 05:03 PM   #8
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Originally Posted by DannoXYZ View Post
heh, heh... Harleys can go as fast as prudent or practical on public roads...
Adding throttle AND lean may not be safe...

Link to original page on YouTube.

Here's some threads on how to bump power on 250:
https://www.ninjette.org/forums/showthread.php?t=257420
https://www.ninjette.org/forums/showthread.php?t=187321
https://www.ninjette.org/forums/showthread.php?t=263401
https://www.ninjette.org/forums/showthread.php?t=89190 (I believe this bike & engine is for sale)

The Balls!

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Old June 23rd, 2020, 04:33 AM   #9
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I own a 2006 250 ninja. Just did the valve adjustment by the way.
You have to ask yourself what can you do to an engine that will rev to 14,000 rpms. That fact alone has to tell you Kawasaki is wringing max out of that motor.

I also own a bunch of Harley’s. Harley leaves a ton of power in the motor. Why? They want to sell you all sorts of aftermarket add-ones. My Fatboy has Rush slip-one ($400 dollars), Screaming Eagle tuner (the one Harley got a $15,000,000 Million dollar fine for selling, cost $450 dollars) cam (another $500 dollars) air cleaner($250 dollars). Oh yea I forgot Dyno time, another $1,000 dollars. Gain 20 HP and 25 foot pounds in torque. That is a big price to pay to knock off a second or two in the quarter mile. Did I mention I drive my Fatboy more than a 1/4 mile at a time. Harley gets folks to think they need to get that extra HP.

Don’t confuse your 250 pregen ninja with a Harley. Kawasaki already extracted the HP. Harley survives selling add-ones, leather goods, t-shirts and all manner of shinny stuff.

About all you can do is change the sprockets to push your ride from max acceleration at One end to top speed on the other.

My advice is leave it alone, it is not a Harley! Plus open pipes on a 250 ninja is never going to sound like a Harley.
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Old June 23rd, 2020, 05:11 AM   #10
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Once you're in 1st gear and get to the max HP RPM, the lower sprocket ratio won't help anyway, since from then on you shift stay in the max HP band. You may be in 3rd when the guy with stock sprockets is still in 2nd, for example.
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Old June 23rd, 2020, 05:48 AM   #11
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Once you're in 1st gear and get to the max HP RPM, the lower sprocket ratio won't help anyway, since from then on you shift stay in the max HP band. You may be in 3rd when the guy with stock sprockets is still in 2nd, for example.
I believe you still get an advantage in acceleration in all gears due to better torque multiplication with a lower gear ratio, but it may not be worth the extra shifting and higher cruising RPMs.
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Old June 23rd, 2020, 06:02 AM   #12
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JVK
The pregen already has a low first gear. I think it is there to make it easier for beginners two get it moving forward. Just change the sprocket to make first gear more usable before to got to slam second.
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Old June 23rd, 2020, 01:37 PM   #13
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I believe you still get an advantage in acceleration in all gears due to better torque multiplication with a lower gear ratio, but it may not be worth the extra shifting and higher cruising RPMs.
I know, you and I have been though this before. When the guy with the smaller front sprocket shifts to 2nd and the other guy is still in 1st, who has the lower gear ratio? Once you're both staying near the peak HP rpm, the sprocket ratio becomes unimportant, since the overall ratio becomes, on the average, equal. In any particular gear, the small front sprocket has the advantage, but small front sprocket guy and big front sprocket guy do not shift to keep themselves in the same gear, they shift to stay near the HP peak.
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Old June 23rd, 2020, 04:39 PM   #14
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I don't believe there is a clear best answer here, other than "it depends". If the shifting was instantaneous, a 100+ gear transmission would be awesome, keeping the bike within a few dozen rpms of the power peak and accelerating the bike as quickly as possible. Theoretically that means a CVT would be optimal, but there is so much drag and loss in one that it negates any advantage. But if the shifting time took 8 minutes per shift, the best transmission would have 1 gear, and dealing with the bike running so far away from its power band for so long would still be faster than a single shift to make it better.

So everything in between is a compromise/optimization problem. The right amount of gear changes and how much it slows/speeds up acceleration compared to optimal depends on that shift speed, and also how much the engine power varies as it gets farther above and below its power peak.
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Old June 23rd, 2020, 04:46 PM   #15
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Thank you all for the suggestions. I probably will keep it the same for now....especially seeing how I went through the bike this weekend for maintenance that I have been neglecting. I am embarrassed to say the date code on my tires are 2008!!!!! Plenty of tread and no tell tale signs of them being bad but at certain times I do not feel comfortable under them. It's hard to explain, somedays they are fine while others I'm pulling over to see if anything is frickin loose. Probably should get new tires before anything!!! It's a 250 and I do abuse it to be honest. Clutchless shifts.....play the no brakes game.... only downshift to stop. That kind of thing. Don't get me wrong, she is taken care of as far as oil changes, brake fluid/pads, coolant.....

She's due for valve clearance but I figure I will do all that this Winter
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Old June 23rd, 2020, 10:25 PM   #16
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Sounds like you should check steering-bearings as well.
And wheel-bearings.

Worn-out bearings there can cause nervousness in bike's handling.
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Old June 24th, 2020, 05:56 AM   #17
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I know, you and I have been though this before. When the guy with the smaller front sprocket shifts to 2nd and the other guy is still in 1st, who has the lower gear ratio? Once you're both staying near the peak HP rpm, the sprocket ratio becomes unimportant, since the overall ratio becomes, on the average, equal. In any particular gear, the small front sprocket has the advantage, but small front sprocket guy and big front sprocket guy do not shift to keep themselves in the same gear, they shift to stay near the HP peak.
I didn't think so.

You have a mechanical advantage with lower final gearing in all gears and it helps make accelerating easier for the engine all the time. I thought it was referred to as increased "thrust".

If two of the exact same cycles are at the drag strip, the one with the lower gearing is going to accelerate quicker. If that ratio is too low the cycle with the taller gearing may eventually pass it due to the other topping-out.

We need an Engineer to chime-in and set the record straight.
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Old June 24th, 2020, 08:57 AM   #18
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It's close, but to fully calculate it still comes down to it depends. You're right - acceleration is directly related to the amount of thrust at the rear wheel. But that thrust isn't a single number, it varies based on the rpm of the engine. The way to graph it is a thrust chart, that shows thrust by RPM, and graph it for each gear on the same plot. The overall acceleration is then calculated by the area contained in that graph, for the time that all of the gears that are held during the full acceleration. Maximizing instantaneous thrust (by having the absolutely shortest gearing), isn't the same as maximizing thrust during acceleration (the shortest gearing possible taking into account how much the thrust changes above and below the peak, and taking into account shifting speed) - you want the maximum area under the curve.



The rest of that page this comes from goes into quite a bit of detail about how this is calculated, that might be interesting to some.
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Old June 24th, 2020, 09:21 AM   #19
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We need an Engineer to chime-in and set the record straight.
I keep trying to.

It's the overall ratio from the engine crankshaft to the rear wheel that matters. When you're starting off the line and haven't gotten to peak HP yet, low overall reduction ratio helps, so a greater reduction at the final drive is good. Once you get past peak HP in 1st gear and you can shift the transmission to stay near the HP peak, the sprocket ratio, which is just a part of the overall ratio, gets absorbed into the overall ratio and has little meaning.

There is the small effect of transmissions usually being designed so that the change in ratio is less between the higher gears, so with a lot of final reduction you get into higher gears with smaller differences sooner, which as Alex was saying above, lets you stay closer to the actual HP peak. That is important at the drag strip, but probably not noticeable at the seat of the pants during street riding.
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Old June 24th, 2020, 09:48 AM   #20
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Maximizing instantaneous thrust (by having the absolutely shortest gearing), isn't the same as maximizing thrust during acceleration (the shortest gearing possible taking into account how much the thrust changes above and below the peak, and taking into account shifting speed) - you want the maximum area under the curve.

Yes, that's correct. Comparing and graphing instantaneous thrust is the key, rather than looking at average-thrust over time-period you're in that gear. As mentioned before, you have to account for the time required to shift. And that extra shift may negate the improvement in acceleration depending upon the distance you're covering. Would be interesting to do that graph for Ninjette compared to Ducati. With its higher revving engine and lower-torque, we may see that it's faster to redline every gear instead of shifting earlier.

Similar to this graph I made 30-yrs ago when I was drag-racing. This was obtained with an accelerometer, so it accounts for tyre-slippage in low gears as well as aerodynamic drag in higher gears.



In this case, due to spread of gears in car, it's best to redline each gear to take advantage of higher torque-multiplication (and linear-thrust at contact patch), rather than to shift right after torque-peak. Until 4th-gear where acceleration would be faster in 5th @ 125mph. This was important data as I was hitting just around 120-122mph at end of 1/4-mile, so shifting to 5th would be faster. However, it has to be balanced with loss of time doing the shift itself. If I had more power to hit 130mph, it would probably be faster to go with taller-gearing to avoid having to shift to 5th and losing that 0.3s from shifting.

BTW - integrating graph with respect to time & distance gets you area-under-curve. which is HP at wheels on ground. Interesting thing is while torque & thrust changes with gearing, HP at wheels does not. That's because HP is force/thrust per unit time per unit distance. So higher torque (1st-gear) in less time & distance is same HP at wheels as lower-torque (2nd-gear) over longer time-period and longer distance. All those "calculators" that estimate 1/4-mile times based on just peak-HP is way, way off.
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Old June 25th, 2020, 06:17 AM   #21
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Thanks Danno - I figured you would have some insight.

But...all that data still has me confused - who is right?
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Old June 25th, 2020, 07:43 AM   #22
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Thanks Danno - I figured you would have some insight.

But...all that data still has me confused - who is right?
I'm not sure why you don't believe the point I'm making, which is once you're up to the HP peak and can stay near it, the final drive ratio has little to do with acceleration. I have a degree in mechanical engineering and have worked in the field for 40 years if that matters. I was trying to argue the point on its merits and not mine though.

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Old June 25th, 2020, 09:42 AM   #23
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Thanks Danno - I figured you would have some insight.

But...all that data still has me confused - who is right?
I think the question has become a little muddled - all of the guidance people are sharing here is generally correct. If the question is the simplest form of "If you compare bikes of the same power, will the bike with lower gearing always accelerate faster?" the answer is no. It very well may, and in most real world cases with a small difference in gearing, it might even be probable, but it's not an iron-clad rule for the reasons that have been laid out here. The bike with optimal gearing to allow the most effective power to the rear wheel throughout the entire acceleration run will accelerate the quickest. If geared too low or too high - optimized gearing on the bike next to it will triumph.
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Old June 25th, 2020, 11:06 AM   #24
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Thanks Danno - I figured you would have some insight.

But...all that data still has me confused - who is right?
Both right, just talking about different things. What most people don't account for is the time shifting. To make that apparent, you can drag-race two identical bikes and you'll see that lower-geared bike may take off faster, but has to shift sooner. Depending upon length of race, say 1/8-th mile, normal bike may do 2 shifts while one with lower-gearing has to do 3 shifts.

So it's yo-yo effect, where lowered-gear bike gets ahead, but is then overtaken when it has to shift sooner. With the minor improvement with just 1-tooth change in front or rear, I don't think you gain enough ground to make up for lost time in shifting.
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Old June 25th, 2020, 11:08 AM   #25
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I'm not sure why you don't believe the point I'm making, which is once you're up to the HP peak and can stay near it, the final drive ratio has little to do with acceleration. I have a degree in mechanical engineering and have worked in the field for 40 years if that matters. I was trying to argue the point on its merits and not mine though.
It's actually torque that accelerates. Comes from F=ma at contact-patch. Rear-wheel torque is divided out by radius of wheel+tyre to generate linear-thrust F for instantaneous acceleration. HP is result of torque over time and distance. It's cause & effect, but it starts with torque first.

Also confirmed by acceleration curves, which actually matches torque curve, not HP. Notice that peak-HP occurs near redline on Ducati Monster, but acceleration curve matches torque-curve with max-acceleration occuring at torque-peak in mid-range, not HP-peak.

2007 Ducati Monster S2R1000 - Rider Mag


We see that max-acceleration in each gear occurs in mid-range RPM, not at redline.
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Old June 25th, 2020, 01:43 PM   #26
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My intention was not to debate what can shave 1/10 of a second off quarter mile times. It was to point out that telling someone looking to improve his street performance that a greater final drive reduction ratio will provide better acceleration throughout the entire speed range is not correct.

A 250 is not limited by tire spin or keeping the front tire on the ground, so a greater final drive reduction ratio will help acceleration while in 1st gear. As I've said repeatedly, once you get to where you're around the HP peak and are shifting to try to stay near there, final drive ratio is quite unimportant for street riding. You're shifting to adjust the overall drive ratio to keep it where you need it to be.

If the final reduction is greater, it will lower the speeds at which you shift into higher gears, but on the average you will have the same overall reduction ratio as someone with a lower final drive reduction ratio. In both situations you're shifing to stay as near as possible to the max acceleration part of the HP curve, wherever that might be.

Things like the time to shift, and the fact that the ratio differences between higher gears are less than between lower gears are small effects that are important on the drag strip for getting every last bit of performance, but are not going to be felt in seat of the pants while street riding.
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Old June 25th, 2020, 05:32 PM   #27
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Yep, changing sprockets isn’t really going to make significant enough different to be worth it. The time wasted on extra shift will negate any gains.

On my track bike, i’ll actually go to taller gearing if it saves me couple extra shifts per lap.
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Old June 25th, 2020, 07:45 PM   #28
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Quote:
Originally Posted by DannoXYZ View Post
Yep, changing sprockets isn’t really going to make significant enough different to be worth it. The time wasted on extra shift will negate any gains.

On my track bike, i’ll actually go to taller gearing if it saves me couple extra shifts per lap.
That's an advantage on the street too, avoiding lots of extra shifts because you put on a small front sprocket in hopes of better acceleration.
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Old June 25th, 2020, 07:59 PM   #29
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And faster chain & sprocket wear as well.
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Old June 26th, 2020, 09:15 AM   #30
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Well, there we go then...

I've personally geared my 650 up to drop the cruising RPMs and smooth out the cruise - which it did.

It does extend my shifts, but I wouldn't say it was that noticeable. No real mileage increase to speak of. Just dropped the RPMs enough to get me out of a area that had a bit too much vibration.

I also geared the Derbi up from stock, as the bigger carb and pipe gave it a bit more pull than stock.

I agree that gearing down on the street doesn't produce big benefits, but depending on the stock gearing and other factors it could get you some improvements with certain cycles.
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Old June 26th, 2020, 09:37 AM   #31
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You can always downshift to accelerate, once you're past 1st gear. You just might need to downshift farther if you have a taller final drive ratio.
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Old July 16th, 2020, 08:24 PM   #32
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I have a buddy that thought if he took a vacuum cleaner motor and plumbed it into the intake of his truck it would boost the power. Well he didn't realize it ran on 110v AC and couldn't figure out why it worked before he took it apart but wouldn't work when it was hooked up to the truck battery!! Long story short there is very little that's free in the HP world.
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Old July 17th, 2020, 07:44 PM   #33
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hahahahah!!!

Electric supercharger resurfaces again!!!!

There was guy on Porsche boards that was marketing one about 20-yrs ago. Biggest crock ever! What he didn't realise was that electric motors aren't 100% efficient. And they don't have positive displacement (fan blades aren't sealed). So to generate just 1psi of boost, he had to draw something like 1000-amps through it and spin it madly @ 30000rpms+. Power required to run the thing was more than what was gained.

Heck, even mechanically-driven superchargers will suck up 25-35% of engine's original power to spin it.
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Old July 17th, 2020, 07:51 PM   #34
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Yeah when I drove up to his house I couldn't stop laughing!! He got mad cause I kept telling him that he needed a power inverter if he wanted it to work. He couldn't understand that the power in the car was different than what the motor needed. He kept saying that it was the fuse. It wasn't letting enough power through to power the motor. Then he wanted to hook it directly to the alternator!! I couldn't stay any longer it was just too funny and he was about to kick my butt!!
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Old July 17th, 2020, 08:05 PM   #35
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Don't laugh too hard... there are electric supercharger kits for cars that really work. They're relatively expensive though.
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Old July 17th, 2020, 08:34 PM   #36
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Quote:
Originally Posted by Triple Jim View Post
Don't laugh too hard... there are electric supercharger kits for cars that really work. They're relatively expensive though.
Well, I can see a roots-style supercharger working with electric motor. Got a link to this thing?

Pretty popular with hot-rodders to scavenge breakers for Eaton superchargers from '90s Thunderbirds. Probably easiest and cheapest way to get decent 20-25% bump in power. I had an MR2 Supercharged way back in '80s. Boy was that a fun car!
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Old July 17th, 2020, 08:37 PM   #37
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Quote:
Originally Posted by Dieseldog View Post
Yeah when I drove up to his house I couldn't stop laughing!! He got mad cause I kept telling him that he needed a power inverter if he wanted it to work. He couldn't understand that the power in the car was different than what the motor needed. He kept saying that it was the fuse. It wasn't letting enough power through to power the motor. Then he wanted to hook it directly to the alternator!! I couldn't stay any longer it was just too funny and he was about to kick my butt!!
Heheh... Not to mention diffrence between 3-phase AC motors vs a DC one!
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Old July 17th, 2020, 08:37 PM   #38
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Have you seen the guy on YouTube that tests crap like electric turbos and those inline little impeller kits that claim to boost HP. I can't remember the name but I saw a few of his videos and they're funny. His name is Cletus Macfarland or something like that.
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Old July 17th, 2020, 08:58 PM   #39
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Quote:
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Well, I can see a roots-style supercharger working with electric motor. Got a link to this thing?
You can find videos of the real ones among the silly ones on YouTube. They're centrifugal, with motors that spin like 70,000 rpm and run off 48v from separate batteries.

Edit: Here's one to get you started: https://www.youtube.com/watch?v=7a_J2X88fSE
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Old July 18th, 2020, 02:15 AM   #40
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OEMs are looking into these electric turbo's a bit more. Check out the two links below about what Mercedes is developing:

https://www.roadandtrack.com/new-car...-turbocharger/

https://www.roadandtrack.com/new-car...x-engine-tech/

They have been snake oil for years, but these developments certainly seem more legitimate.
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