ninjette.org

Go Back   ninjette.org > 2008 - 2012 Ninja 250R > 2008 - 2012 Ninja 250R Tech Talk

Notices

Reply
 
Thread Tools
Old July 3rd, 2019, 11:34 PM   #1
XeJive
ninjette.org newbie
 
Name: Aaron
Location: Denver
Join Date: Jul 2018

Motorcycle(s): Ninja 250r, ZG1000

Posts: 4
Unhappy Low Speeds High RPMs HELP!

2012 Ninja 250r
Bought "used" with 70 miles on it.


The bike now has almost 3k miles on it but its had this issue since day one and I only feel like its getting worse.
The bike has no problem idling or running, but its top end speeds are greatly reduced from what I've seen other people have on similar stock bikes.
Since day one I've been trying to find the source of the problem cleaning the already flawless carbs, adjusting the Fuel/Air ratio, checking the air filter spark plugs, gear ratio, all to no avail.
I haven't paid much attention to low gears but recently I've been getting around 60-65mph at around 9.5-10k rpm, If I WOT I can squeeze around 80mph out of her at red line after probably 30 seconds from 60mph. Just today it was particularly hot outside and it dropped to 55mph at 10k rpm.
I work about 30 miles away from where I live and like the bike for its gas mileage but I hate making the engine scream just to keep up with traffic and I find it quite dangerous that I have no top end left in case of emergency.
I've scoured the web and found no real answer.
Last thing I can think to mention is that early on I discovered spotty Y hose connectors and hoses routed to the wrong places in the carb. I rectified all the problems and the routing is back to stock. After speaking with a long time bike mechanic we think the bike came from Cali and had work to meet stricter regulations there. I think this is what is causing this issue if they changed something that I haven't looked at yet but maybe not.
XeJive is offline   Reply With Quote




Old July 4th, 2019, 03:45 AM   #2
59096
ninjette.org member
 
59096's Avatar
 
Name: Garry
Location: Bungendore Australia
Join Date: Jan 2019

Motorcycle(s): GPX250 1989 model and 1990 model

Posts: 98
Quote:
Originally Posted by XeJive View Post
2012 Ninja 250r
Bought "used" with 70 miles on it.


The bike now has almost 3k miles on it but its had this issue since day one and I only feel like its getting worse.
The bike has no problem idling or running, but its top end speeds are greatly reduced from what I've seen other people have on similar stock bikes.
Since day one I've been trying to find the source of the problem cleaning the already flawless carbs, adjusting the Fuel/Air ratio, checking the air filter spark plugs, gear ratio, all to no avail.
I haven't paid much attention to low gears but recently I've been getting around 60-65mph at around 9.5-10k rpm, If I WOT I can squeeze around 80mph out of her at red line after probably 30 seconds from 60mph. Just today it was particularly hot outside and it dropped to 55mph at 10k rpm.
I work about 30 miles away from where I live and like the bike for its gas mileage but I hate making the engine scream just to keep up with traffic and I find it quite dangerous that I have no top end left in case of emergency.
I've scoured the web and found no real answer.
Last thing I can think to mention is that early on I discovered spotty Y hose connectors and hoses routed to the wrong places in the carb. I rectified all the problems and the routing is back to stock. After speaking with a long time bike mechanic we think the bike came from Cali and had work to meet stricter regulations there. I think this is what is causing this issue if they changed something that I haven't looked at yet but maybe not.
Perhaps your clutch is slipping?
__________________________________________________
Perpetua Culpa Alterna Vagus
59096 is offline   Reply With Quote


Old July 4th, 2019, 05:34 AM   #3
choneofakind
ninjette.org certified postwhore
 
Name: .
Location: .
Join Date: Feb 2011

Motorcycle(s): .

Posts: Too much.
MOTM - Feb '13, Feb '14
count your sprocket teeth. I had very similar speed vs rpm relationship when I was running +2 gearing on the rear sprocket. stock is 14/45 IIRC

but yes, check the clutch adjustment. very possible for the lever to not allow the clutch to fully disengage if the barrel adjuster is too tight.
choneofakind is offline   Reply With Quote


Old July 4th, 2019, 11:47 AM   #4
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: Mesa, AZ
Join Date: Dec 2011

Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Quote:
Originally Posted by XeJive View Post
adjusting the Fuel/Air ratio,
1. What are you doing to adjust AFR?
2. What is AFR before you adjust?
3. What is AFR after you adjust?
DannoXYZ is offline   Reply With Quote


Old July 4th, 2019, 12:16 PM   #5
ducatiman
ninjette.org certified postwhore
 
ducatiman's Avatar
 
Name: Gordon
Location: new york
Join Date: Sep 2009

Motorcycle(s): '95 DUCATI 900SS/SP '07 DUCATI SS800 '19 HONDA CBR650R

Posts: A lot.
MOTM - Nov '18, Mar '17
^ attempted adjusting of the pilot screws would make sense, no?

You need to verify the carb innards are absolutely correct and assembled correctly for your version 250, nobody been in there "modding"...screwin' around, swappin' stuff at any time....other than Mr and Mrs Keihin, that is.

On BOTH carbs verify the size of pilot jets, main jets, # on needles, visually assure the needle jets are BOTH present in all their shining glory (as these commonly "go missing" and could very well be responsible for transition issues)

Verify the pilot screw springs, washers and orings are present too.

Always remember....Clean Carbs Matter.
__________________________________________________
gordon@customcarbservices.com
Custom Carb Service
www.customcarbservices.com
ducatiman is online now   Reply With Quote


Old July 4th, 2019, 03:21 PM   #6
XeJive
ninjette.org newbie
 
Name: Aaron
Location: Denver
Join Date: Jul 2018

Motorcycle(s): Ninja 250r, ZG1000

Posts: 4
The two flat head screws on the bottoms of the carbs. I had adjusted them previously cause it was running really rich, but I put them back to stock (left 2 1/2 turns, right 1 3/4 turns)
XeJive is offline   Reply With Quote


Old July 4th, 2019, 03:29 PM   #7
XeJive
ninjette.org newbie
 
Name: Aaron
Location: Denver
Join Date: Jul 2018

Motorcycle(s): Ninja 250r, ZG1000

Posts: 4
Looks like the clutch disengages all the way and has the 2-3mm of slack. Sprockets are stock
XeJive is offline   Reply With Quote


Old July 4th, 2019, 04:34 PM   #8
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: Mesa, AZ
Join Date: Dec 2011

Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Quote:
Originally Posted by XeJive View Post
The two flat head screws on the bottoms of the carbs. I had adjusted them previously cause it was running really rich, but I put them back to stock (left 2 1/2 turns, right 1 3/4 turns)
How do you know it was running really rich?

Would be helpful to know exact AFR at time it's bogging at WOT going 55mph or 80mph.

Should inspect your slide diaphraghms for sealing issues or pinholes. Also with warmed-up engine, measure manifold vacuum at idle and 3000rpm.
DannoXYZ is offline   Reply With Quote


Old July 4th, 2019, 04:47 PM   #9
XeJive
ninjette.org newbie
 
Name: Aaron
Location: Denver
Join Date: Jul 2018

Motorcycle(s): Ninja 250r, ZG1000

Posts: 4
Youre going to hate me for this response, but I was going off of exhaust fumes (If it smelled really rich id lean it out) Which I feel caused it to be really lean because it was running pretty hot.
Im not exactly sure about your second comment but its basically constant slow acceleration up to 80. I dont really feel a loss of power its just red lining at slower speeds than I would think.
I dont really want to pull the carb again, its a pain in the ass on this bike and it seemed alright to my untrained eye (about a year ago) but if you think its a leading suspect I can give it a look. Worst case I can take it over to the shop and they can have a gander. Expensive though :/
XeJive is offline   Reply With Quote


Old July 5th, 2019, 05:59 PM   #10
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: Mesa, AZ
Join Date: Dec 2011

Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Let's step back a little....

A bike that's been ridden less than 1-mile/month for past 7-years is most likely going to have dirty and clogged carbs. Spray "carb cleaners" do not work! They no longer have chlorinated compounds and are no better at cleaning your carbs than pee! At least that has some ammonia in it and can do some actual cleaning.

These carbs ran perfectly fine when bike rolled off showroom floor. The only reason yours isn't running like scalded cat is because carbs in your bike aren't factory-fresh clean.

Quote:
Originally Posted by XeJive View Post
The two flat head screws on the bottoms of the carbs. I had adjusted them previously cause it was running really rich, but I put them back to stock (left 2 1/2 turns, right 1 3/4 turns)
Please review the following on how mechanical-computers known as carbs work.

https://www.youtube.com/watch?v=AwXRvgyFUG4
https://faq.ninja250.org/wiki/How_a_...arbs_explained

Due to limitations of mechanical-computing, carburetor needs multiple fluid circuits to deal with wide range of airflow and load conditions that exist in motorcyle engines. Some circuits deal with idle mixture, others mid-range and others fulfil WOT high-end operations.



As you can see, adjusting pilot screws for low-end makes zero effect to high-end/high-load mixtures. That's why I asked for actual air-fuel ratio while you are going full-throttle at 55mph and 80mph. AFR under those conditions will be wildly different than sitting at idle.

Again, these carbs worked great when bike left showroom floor, therefore no adjustment is needed away from factory settings. You just need to restore them to factory-fresh clean condition. Please review these threads on what actually needs to be done to fully clean and restore carbs to factory-fresh conditions. Be prepared to remove carbs from bike at least 4-5x more.

https://www.ninjette.org/forums/showthread.php?t=333176
https://www.ninjette.org/forums/showthread.php?t=334365
https://www.ninjette.org/forums/showthread.php?t=330213
https://www.ninjette.org/forums/showthread.php?t=330960
https://www.ninjette.org/forums/showthread.php?t=323737
https://www.ninjette.org/forums/showthread.php?t=323452
https://www.ninjette.org/forums/showthread.php?t=322846
https://www.ninjette.org/forums/showthread.php?t=321223
https://www.ninjette.org/forums/showthread.php?t=317977
https://www.ninjette.org/forums/showthread.php?t=317810
https://www.ninjette.org/forums/showthread.php?t=316395
https://www.ninjette.org/forums/showthread.php?t=315193
https://www.ninjette.org/forums/showthread.php?t=299855
https://www.ninjette.org/forums/showthread.php?t=280658


NOTE: there's clue in those threads on how you can get away with removing your carbs just one time more...

Last futzed with by DannoXYZ; July 6th, 2019 at 06:33 AM.
DannoXYZ is offline   Reply With Quote


Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
High revving ninja, kept at low rpms? rdrgoB Riding Skills 11 July 3rd, 2012 01:36 AM
Up and down surging/hesitation at low RPMs elicash80 1986 - 2007 Ninja 250R Tech Talk 2 August 29th, 2010 04:04 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Motorcycle Safety Foundation

All times are GMT -7. The time now is 04:25 PM.


Website uptime monitoring Host-tracker.com
Powered by vBulletin®
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
Except where otherwise noted, all site contents are © Copyright 2022 ninjette.org, All rights reserved.