March 16th, 2014, 03:19 PM | #1 |
ninjette.org member
Name: Grant
Location: Mid-Michigan
Join Date: Aug 2013 Motorcycle(s): 2006 Ninja 250 Posts: 83
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Advice Needed: Engine Bog @ ~6k 1/4 Throttle
So I bought my bike last year. Its a 2006 and had under 1,500 miles on it at the time.
The carbs were gummed up (bike didn't run) so I pulled them, cleaned them and reinstalled. I rode it all summer and put another 1,000 miles on it. One thing that always bugged me was a bog or stutter that occurred around 50mph while just cruising at ~1/4 throttle in 6th gear. It almost feels like you're hitting a heavy head-wind. The bike runs very well otherwise. WOT is perfect 0-12,000 rpms when taking off. I pulled the bike out of storage and as I wait for warmer weather (thank you Michigan) I figured maybe I could try to fix this problem. Would shimming the carb needles help this 1/4 throttle stutter in 6th gear? I'm seeking some advice before I tear into it. Thanks! |
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March 16th, 2014, 04:08 PM | #2 |
ninjette.org guru
Name: Kevin
Location: Madison
Join Date: Apr 2013 Motorcycle(s): 2004 Ninja 250 Posts: 465
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Is the bike stock?
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March 16th, 2014, 04:26 PM | #3 |
Long Time Rider
Name: Blue
Location: Charlotte, NC
Join Date: Sep 2010 Motorcycle(s): 2009 Kawasaki Ninja 250R Posts: A lot.
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Why cruise @ 50 mph in 6th gear? Why not fifth? At 1/4 throttle in 6th gear you are not getting enough fuel for necessary power.
Here's a 'lil something you can do to help determine throttle position when tuning your carbs. -From Motorcycle Carburetor Theory 101 Place a piece of tape on the throttle housing. Place another piece of tape on the throttle grip and draw a line (while the throttle is at idle) straight across from one piece of tape to the other. When these two lines are lined up, the engine will be idling. Now open the throttle to full throttle and draw another line directly across from it on the throttle housing. At this point, there should be two lines on the throttle housing, and one on the throttle grip. Now find the half-way point between both of the lines on the throttle housing. Make a mark and this will show when the throttle is at half throttle. Divide the spaces up even again until idle, 1/4, 1/2, 3/4, and full throttle positions are known. These lines will be used to quickly find the exact throttle opening while jetting. |
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March 16th, 2014, 04:40 PM | #4 |
ninjette.org member
Name: Grant
Location: Mid-Michigan
Join Date: Aug 2013 Motorcycle(s): 2006 Ninja 250 Posts: 83
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March 16th, 2014, 04:49 PM | #5 | |
ninjette.org member
Name: Grant
Location: Mid-Michigan
Join Date: Aug 2013 Motorcycle(s): 2006 Ninja 250 Posts: 83
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Quote:
What do you and others use as a normal rpm target for extended driving? |
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March 16th, 2014, 05:02 PM | #6 |
ninjette.org guru
Name: Kevin
Location: Madison
Join Date: Apr 2013 Motorcycle(s): 2004 Ninja 250 Posts: 465
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Are you running ethanol free fuel? Also the advance curve at 7 grand changes and there is a flat spot if I remember correctly. That may be part of the problem. Check out a dyno chart of the 250.
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March 16th, 2014, 05:05 PM | #7 | |
Long Time Rider
Name: Blue
Location: Charlotte, NC
Join Date: Sep 2010 Motorcycle(s): 2009 Kawasaki Ninja 250R Posts: A lot.
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Quote:
Also shimming the needles doesn't hurt either. For some bikes it may offer a small performance boost. |
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March 16th, 2014, 05:10 PM | #8 | |
ninjette.org member
Name: Grant
Location: Mid-Michigan
Join Date: Aug 2013 Motorcycle(s): 2006 Ninja 250 Posts: 83
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Quote:
Maybe this is just normal and I happen to hit it all the time because of a long 50mph stretch on my way to work. I was hoping shimming the needles would allow more fuel at the 1/4 throttle point. But first I think I need to use the grip & tape method to find out exactly where the throttle position is at this speed. The 1/4 throttle is just an estimate. |
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