Bike lacks power after installing 15 tooth sprocket...

ReDnEcK · August 19th, 2010, 10:43 PM

Installed a 15 tooth front sprocket and MT-75 tires... I have to shift into 5th now to get enough power to pass cars on the freeway. Is this how its supposed to be?
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SteveL · August 19th, 2010, 11:52 PM

Increasing the gear ratio will result in slower acceleration you just use a lower gear than before when passing other vehicles. From what I know most of the riders who have chosen the 15 tooth front are riding a lot of highway where it makes sense to drop the rpm a little.

Steve

dubojr1 · August 20th, 2010, 04:37 AM

Your bike must be black. Everyone knows green is the fastest!

I'm running the 15T on both my 250's. Most traveling here is done on the interstate. I wouldn't say I would have to switch down to 5th unless I needed to pass quickly. Is this the only issue your having?

FrugalNinja250 · August 20th, 2010, 06:22 AM

The sprocket setup multiplies engine torque, and torque is what makes the wheel turn and the bike accelerate. When you increase the front (or reduce the rear) sprocket sizes you reduce the torque multiplication and therefor reduce power available to the rear wheel. That's normal.

want1sobad · August 20th, 2010, 06:26 AM

jeff,

have you shimmed the needles and pulled the snorkel? if not, that should fix the problem

i have 15t, 2 washers, snorkel pulled, stock exhaust - no issues overtaking on the highway.

Snake · August 20th, 2010, 08:07 AM

His bike is a pregen which does not have the snorkel. Shimming the needles though is a good fix. I have a 15T on mine and 3 shims on each needle. It helped acceleration tremendously.

want1sobad · August 20th, 2010, 08:51 AM

i always forget to check if we're talking about a pregen.....

Snake · August 20th, 2010, 08:54 AM

No worries Vince.

ReDnEcK · August 20th, 2010, 09:51 AM

Quote:

Originally Posted by Snake

His bike is a pregen which does not have the snorkel. Shimming the needles though is a good fix. I have a 15T on mine and 3 shims on each needle. It helped acceleration tremendously.

Its a green '03... before they needed to breathe under water! As for shims... I dont know anything about that. Can you explain what your talking about please?
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Snake · August 20th, 2010, 10:01 AM

Two great threads to read:

http://www.ninjette.org/forums/showthread.php?t=11963

http://www.ninjette.org/forums/showthread.php?t=10208

kkim · August 20th, 2010, 01:49 PM

Quote:

Originally Posted by Snake

Two great threads to read:

http://www.ninjette.org/forums/showthread.php?t=11963

http://www.ninjette.org/forums/showthread.php?t=10208

here's another thread to help explain...
http://www.ninjette.org/forums/showthread.php?t=9465&

CZroe · August 21st, 2010, 01:05 AM

Yup. Obviously, if everything remained the same at lower RPMs/higher MPG, they'd come that way from the factory!

leesic66 · August 29th, 2010, 04:37 AM

I went up in the front and I tell you its the best thing I coulda done!!! SOOOOOmuch smoother

I also rejetted cuz the douchebag who owned the bike b4 me put the pods on and didnt rejet or tell me about it >

I have no problems smoking anything on 4 wheels and I dont even get close to 11k rpms......

Cuongism · August 29th, 2010, 09:15 AM

What gear did you pass cars on the highway before? I have a 15T and 6th gear will still accelerate 70 mph+, but just not as fast as 5th gear.

leesic66 · August 29th, 2010, 10:19 AM

5th..... U should remember thAt I live on an island...... people here dont drive like people on the mainland. in 5th at like 8.5k Im passin EVERYBODY

sprale · September 3rd, 2010, 09:13 AM

I went with a 15/41 for the highways in Texas. Makes lots of difference when cruising for long stretches. I have to drop a gear to pass, it's just a part of the change. It's a Ninja! It's not like you ever get to ride much without constantly changing gears anyway, it just happens slightly more often!

greg737 · September 3rd, 2010, 09:43 AM

I like the idea of changing the gearing to get the slightly lower highway cruising RPMs.

It's pretty obvious that if you're going to do this but you still want the bike's original level of performance, that is to say if you want the bike to "feel" the same acceleration-wise, then you've got to increase it's horsepower just a bit.

If you added an aftermarket exhaust like the Area P full-system and properly re-jetted the carbs you'd get a boost in power. Then put on the longer gearing and you'll break even on the bike's performance and get the bonus of the nice lower-RPM highway cruise.

August 19th, 2010, 10:43 PM	#1
ReDnEcK ninjette.org member Name: JeFFy Location: Ventura, CA Join Date: Jul 2010 Motorcycle(s): 2005 Kawasaki Ninja 250R Posts: 66	Bike lacks power after installing 15 tooth sprocket... Installed a 15 tooth front sprocket and MT-75 tires... I have to shift into 5th now to get enough power to pass cars on the freeway. Is this how its supposed to be? Posted via Mobile Device

August 19th, 2010, 11:52 PM	#2
SteveL old git Name: Steve Location: Geneve Switzerland Join Date: Mar 2009 Motorcycle(s): BMW K1300S Posts: 479	Increasing the gear ratio will result in slower acceleration you just use a lower gear than before when passing other vehicles. From what I know most of the riders who have chosen the 15 tooth front are riding a lot of highway where it makes sense to drop the rpm a little. Steve __________________________________________________ Some mistakes are too much fun to make only once.

August 20th, 2010, 04:37 AM	#3
dubojr1 ninjette.org certified postwhore Name: Jason Location: Jacksonville, Florida Join Date: May 2010 Motorcycle(s): 09 Ninja 250R SE, 07 Honda CRF230F, 06 Honda CRF150F Posts: A lot.	Your bike must be black. Everyone knows green is the fastest! I'm running the 15T on both my 250's. Most traveling here is done on the interstate. I wouldn't say I would have to switch down to 5th unless I needed to pass quickly. Is this the only issue your having? __________________________________________________ 09 250R SE: Paying it forward one post at a time! Don't forget to add yourself to our Member Map

September 3rd, 2010, 09:13 AM	#16
sprale Dead-thread Necromancer! Name: Levon Location: Central Texas Join Date: Sep 2008 Motorcycle(s): K5 V-Strom Posts: 144 Blog Entries: 3	I went with a 15/41 for the highways in Texas. Makes lots of difference when cruising for long stretches. I have to drop a gear to pass, it's just a part of the change. It's a Ninja! It's not like you ever get to ride much without constantly changing gears anyway, it just happens slightly more often! __________________________________________________ Dead-thread Necromancer! 2007 Kawasaki Ninja EX250 ZG250 Quarter-Concours commuter Gone 2005 Suzuki V-Strom DL1000 Big Black Vee future hack?

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August 20th, 2010, 06:22 AM	#4
FrugalNinja250 ninjette.org certified postwhore Name: Frugal Location: Dallas/Fort Worth (DFW) Join Date: Mar 2010 Motorcycle(s): Several Posts: A lot.	The sprocket setup multiplies engine torque, and torque is what makes the wheel turn and the bike accelerate. When you increase the front (or reduce the rear) sprocket sizes you reduce the torque multiplication and therefor reduce power available to the rear wheel. That's normal.

August 20th, 2010, 06:26 AM	#5
want1sobad Ninjette CPT Name: Vince Location: jacksonville, fl Join Date: May 2009 Motorcycle(s): Black 08 250r Posts: A lot.	jeff, have you shimmed the needles and pulled the snorkel? if not, that should fix the problem i have 15t, 2 washers, snorkel pulled, stock exhaust - no issues overtaking on the highway.

August 20th, 2010, 08:07 AM	#6
Snake ninjette.org certified postwhore Name: Rick Location: Alexandria, Louisiana Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much. MOTY - 2017, MOTM - Jan '19, Oct '16, May '14	His bike is a pregen which does not have the snorkel. Shimming the needles though is a good fix. I have a 15T on mine and 3 shims on each needle. It helped acceleration tremendously.

August 20th, 2010, 08:51 AM	#7
want1sobad Ninjette CPT Name: Vince Location: jacksonville, fl Join Date: May 2009 Motorcycle(s): Black 08 250r Posts: A lot.	i always forget to check if we're talking about a pregen.....

August 20th, 2010, 08:54 AM	#8
Snake ninjette.org certified postwhore Name: Rick Location: Alexandria, Louisiana Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much. MOTY - 2017, MOTM - Jan '19, Oct '16, May '14	No worries Vince.

August 20th, 2010, 10:01 AM	#10
Snake ninjette.org certified postwhore Name: Rick Location: Alexandria, Louisiana Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much. MOTY - 2017, MOTM - Jan '19, Oct '16, May '14	Two great threads to read: http://www.ninjette.org/forums/showthread.php?t=11963 http://www.ninjette.org/forums/showthread.php?t=10208

August 21st, 2010, 01:05 AM	#12
CZroe CPT Falcon Name: J.Emmett Turner Location: Newnan, GA Join Date: Apr 2009 Motorcycle(s): '08 CP Blue EX250J, '97 unpainted EX250F, 2nd '97 unpainted EX250F (no engine), '07 black EX250F Posts: A lot.	Yup. Obviously, if everything remained the same at lower RPMs/higher MPG, they'd come that way from the factory!

August 29th, 2010, 04:37 AM	#13
leesic66 ninjette.org member Name: Lee Location: Honolulu Join Date: Apr 2010 Motorcycle(s): 2005 Ninja 250 Posts: 17	I went up in the front and I tell you its the best thing I coulda done!!! SOOOOOmuch smoother I also rejetted cuz the douchebag who owned the bike b4 me put the pods on and didnt rejet or tell me about it > I have no problems smoking anything on 4 wheels and I dont even get close to 11k rpms......

August 29th, 2010, 09:15 AM	#14
Cuongism ninjette.org certified postwhore Name: Cuong Location: San Diego Join Date: Jul 2010 Motorcycle(s): 2008 Ninja 250r, 2007 Daytona 675 Posts: A lot.	What gear did you pass cars on the highway before? I have a 15T and 6th gear will still accelerate 70 mph+, but just not as fast as 5th gear.

August 29th, 2010, 10:19 AM	#15
leesic66 ninjette.org member Name: Lee Location: Honolulu Join Date: Apr 2010 Motorcycle(s): 2005 Ninja 250 Posts: 17	5th..... U should remember thAt I live on an island...... people here dont drive like people on the mainland. in 5th at like 8.5k Im passin EVERYBODY

September 3rd, 2010, 09:43 AM	#17
greg737 - Name: - Location: - Join Date: May 2009 Motorcycle(s): - Posts: A lot.	I like the idea of changing the gearing to get the slightly lower highway cruising RPMs. It's pretty obvious that if you're going to do this but you still want the bike's original level of performance, that is to say if you want the bike to "feel" the same acceleration-wise, then you've got to increase it's horsepower just a bit. If you added an aftermarket exhaust like the Area P full-system and properly re-jetted the carbs you'd get a boost in power. Then put on the longer gearing and you'll break even on the bike's performance and get the bonus of the nice lower-RPM highway cruise.