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Old July 15th, 2011, 01:24 AM   #1
Timon
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Intake Lid Modification

As most of you know the new Ninjas seem to have quite a popular mod of removing the snorkel to go along with shimming the carbs. Well on the pregens it isn't quite so easy without going to a full cone filter setup. I decided I'd give a little DIY a try and see how I liked it.

I decided to modify the intake lid, as this obviously is the primary point which air enters the carbs. I'll save the DIY of removing the lid as I'm sure most people know how to do that much.

Basically I just removed the two plastic tubes on the lid to allow more air to flow into the carbs. I decided to do this as opposed to removing the lid entirely to allow me to keep the stock air box, filter, and keep the plastic bracket the holds the filter in place.

Anyway, here are the pics, don't mind the finished product, it was still wet from washing it after sanding.

Cut off one of the plastic cylinders.


Finished the second.


After the tubes were removed using a dremel cutting disc, I went back through with a grinding wheel and evened out the edges. The leftover, flappy plastic was removed with some light sanding with 300-600 grit sandpaper. To make sure no extra plastic was going to come off I took a lighter and heated the edges of the newly cut holes to melt down any rough edges and give it a smooth surface.

Shaped the new square holes and washed the intake lid.




Reinstalled on the bike.


Overall it seems to have a much more throaty tone at anything higher than 50% throttle. Idle seems to sound pretty much the same. It really growls up around the 9k mark. On the freeway you hardly notice much of a noise difference due to the wind noise.

I honestly can't say if it really helped other than the noise. Right now I'm still running the stock exhaust with the needles at one washer. I'm debating adding a second one for the time being - any thoughts on this are welcome. Eventually if I go with aftermarket pipes I'll probably add a third washer.
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Old July 15th, 2011, 06:13 AM   #2
choneofakind
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looks great! Ive wanted to do this for a while I've just been too lazy. how do the main jets feel on full throttle? aftermarket pipes lean it a bit. idk if the combination of that and this would be too much
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Old July 15th, 2011, 07:47 PM   #3
shiftdrift06
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Cool diy!

I would suggest the filter pods if you tune the carbs alot...

I hate removing that damn airbox
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Old July 15th, 2011, 11:36 PM   #4
Timon
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The low end does seem to a bit less torquey. We'll see what happens when I add another shim to the needles. I think 1 shim with this mod just puts it closer to the stock feeling.
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Old July 16th, 2011, 02:53 AM   #5
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Great diy!
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Old July 16th, 2011, 12:06 PM   #6
DaBlue1
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Can't go wrong with another shim or 2. You need a little more fuel for the large amount of air you're getting now. You probably should have just cut off the cones flush and went to a bigger opening as needed. If the engine response is not improved at WOT, a larger main jet may be needed.
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Old July 16th, 2011, 04:03 PM   #7
Timon
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I added another 2 washers to each of the fuel needles. I'll give it a go around today and see how she feels.

Edit: 2 additional washers (3 total) seemed to be a bit much, it had some power issues in the upper end. I dropped it down to 2 washers and it pulls hard all the way to redline. I'm very happy with 2 washers and this intake mod with the stock pipes for now.

Last futzed with by Timon; July 16th, 2011 at 07:32 PM.
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Old November 27th, 2011, 07:02 PM   #8
choneofakind
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I did this to my bike over thanksgiving break. LOVE IT. sounds SO throaty, and the mid-range pulls stronger than before. I've got 3 washers on the needles it pulls hard, it's just a little soupy (I think its rich). I'm gonna have to play with the jetting a bit in the spring. The top end seems a little lacking to me. I'll try some Keihin 108's (which I think will be too much. It's not THAT lean) and Precision Engineering's 102.5's. I might get an FP jet kit as well to smooth out the midrange a bit. shimming works for just getting the fuel there, but the shop says the FP/DJ needles make a huge difference

this chart gives a comparison of flow rates and sizes of different jets
http://faq.ninja250.org/wiki/Dynojet...zes_conversion
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Old March 3rd, 2012, 11:10 PM   #9
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A tip for this mod:

I filed the edges all down really carefully so they were straight and square, and then used a blowtorch back and forth lightly over the cuts. This really cleaned up the edges and looks a lot better.




Last futzed with by choneofakind; March 22nd, 2012 at 01:48 PM.
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