July 31st, 2015, 02:07 PM | #1 |
ninjette.org member
Name: Firstname
Location: USA
Join Date: Sep 2010 Motorcycle(s): Yamaha RD350, H-D Electraglide, BSA Lightning, Suzuki GS550 Posts: 12
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Runs lean?
Hello,
I have a 2003 Ninja 250 that my brother will hopefully be using, but it seems to have an issue where it is very slow to come back down to idle. With the enrichener on, it starts to rev higher as well, so I assume it is running very lean. I already replaced the manifolds and cleaned the carbs and all that basic stuff, but I am not sure what is going on. Everything seems to be in order. I am wondering if its the jetting of the bike now. I tried to look it up, but I can't seem to find what the stock jetting of the bike should be. I will be taking the carbs off tomorrow to check them and want to compare against what SHOULD be in there. Bike is 100% stock. Semi related, are there specific jet sizes that are recommended here for the stock bike that might differ from the stock jets as well? Aside from that, any idea what could be causing the slow to come down to idle/lean issue? I can't seem to find any air leaks either. Thanks for any help/
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03 H-D Electraglide, 75 Yamaha RD350 cafe, 79 Suzuki GS550L with sidecar hack, 71 BSA Lightning 650, 14 Ducati Monster 796 |
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July 31st, 2015, 02:16 PM | #2 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
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That's typical of a vacuum leak. Spray something around the intake boots (between the carb and the engine) and see if you get a change in RPMs.
As far as carb adjustments go, if you remove the carbs you will want to remove the caps on the idle mixture screws so you can make adjustments - http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F A good base setting is around 2 1/2 turns out, but it's usually set leaner (less turns out) from the factory. This section may have some answers - http://faq.ninja250.org/wiki/Intake |
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July 31st, 2015, 02:23 PM | #3 | |
ninjette.org member
Name: Firstname
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Join Date: Sep 2010 Motorcycle(s): Yamaha RD350, H-D Electraglide, BSA Lightning, Suzuki GS550 Posts: 12
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Quote:
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03 H-D Electraglide, 75 Yamaha RD350 cafe, 79 Suzuki GS550L with sidecar hack, 71 BSA Lightning 650, 14 Ducati Monster 796 |
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July 31st, 2015, 02:36 PM | #4 | |
in your machine
Name: Scott
Location: Summer Shade, Ky.
Join Date: Oct 2014 Motorcycle(s): 98 Ninja 250/F12 aka ZX-2R "SERENITY", 91 Ninja 500/A5 aka ZX-5R "Phoenix", 84 Honda GL1200A "SIREN" Posts: A lot.
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How did you clean the carburetors? Did you verify all fuel circuits were clear with a air compressor?
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August 1st, 2015, 12:55 PM | #5 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
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That would suggest the passages are plugged or the o-rings on the idle mixture screws are deteriorated, ripped, or not in the correct position.
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1 out of 1 members found this post helpful. |
August 2nd, 2015, 08:58 AM | #6 |
ninjette.org certified postwhore
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1) clean carbs thoroughly as suggested.
2) check for vacuum leaks by looking for broken hoses, spraying boot connections while running, etc. Stock idle jet is keihin 38, stock main is keihin 105. The enricher we have will raise the idle. It's supposed to do this. It is an enricher that draws both fuel and air, not a choke that just reduces air. |
1 out of 1 members found this post helpful. |
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