Question about main jets

Tubesock · July 8th, 2009, 04:32 PM

Hey guys I just finished my custom exhaust that I made using the instructions from a different site (sorry, I swear this is my favorite site though!!!) Ok so here's the dyno results from the original exhaust it's in a post in the upper middle of the page.
http://www.newninja.com/modification...r-(video)/135/
As you can see there is a loss of torque and horsepower in-between 8k and 10k rpms. Now I'm also going to take out the snorkel and my question is what size main jet do you guys think I should use to fix the flat spot in the rpm range?

kkim · July 8th, 2009, 04:35 PM

use the stock main jets (98).

Raise the needles on clip position (lower the clip) to take care of the flat spot.

is your jetting completely stock now?

Tubesock · July 8th, 2009, 06:05 PM

Yes it's totally stock (I'm such a slacker I haven't even shimmed the needles). But would raising the needle effect the rpm range that high? Also will #6 washers work for shimming?

Wes · July 8th, 2009, 06:30 PM

If I had to guess, I'd say you're going to need to go up on main jet size, but you should try popping a couple of washers under the needles first.

Use #4 washers. They're the right size and cost about a nickel each.

Wes

CANTFUNCTION · July 8th, 2009, 06:39 PM

Quote:

Originally Posted by Tubesock

Yes it's totally stock (I'm such a slacker I haven't even shimmed the needles). But would raising the needle effect the rpm range that high? Also will #6 washers work for shimming?

No #6 washer will not work

you need #4 or 3mm

Tubesock · July 8th, 2009, 07:22 PM

As far as the main jet goes what would be a good size to try first?

kkim · July 8th, 2009, 07:24 PM

keep the stock. the bike is rich on the top end as delivered.

you need to fatten up the midrange, which is the needle circuit.

Tubesock · July 8th, 2009, 07:26 PM

Oh ok I get what you're saying now.

MysterioX · April 20th, 2012, 11:27 PM

I have a problem of jets getting clogged. Is it the main jet I need to replace?
Someone suggested getting slow jet #38 or 40 will fix the problem.

choneofakind · April 21st, 2012, 09:10 AM

Quote:

Originally Posted by MysterioX

I have a problem of jets getting clogged

clean the carbs. problem solved.

MysterioX · April 21st, 2012, 09:42 PM

Quote:

Originally Posted by choneofakind

clean the carbs. problem solved.

Let me get this straight, so every time I have clogged jets problem I have to clean them instead of just replacing pilot jets?

Don't let me stop you, but I prefer to address fixable problems only once!

choneofakind · April 22nd, 2012, 09:10 AM

Just replacing pilot jets won't necessarily do the trick. There's little passageways that are used during various throttle openings that also get clogged. You'll only have to do it once as long as you're careful to not let it sit for months without draining the carbs and stabilizing gas.

I've only cleaned mine once and since it gets ridden regularly and properly winterized every winter, I've never had to clean them again since.

July 8th, 2009, 04:32 PM	#1
Tubesock ninjette.org member Name: David Location: Chatta-vegas Join Date: May 2009 Motorcycle(s): 2009 Kawasaki Ninja 250r Posts: 69	Question about main jets Hey guys I just finished my custom exhaust that I made using the instructions from a different site (sorry, I swear this is my favorite site though!!!) Ok so here's the dyno results from the original exhaust it's in a post in the upper middle of the page. http://www.newninja.com/modification...r-(video)/135/ As you can see there is a loss of torque and horsepower in-between 8k and 10k rpms. Now I'm also going to take out the snorkel and my question is what size main jet do you guys think I should use to fix the flat spot in the rpm range? __________________________________________________ "When I die I want mud on my jump boots, magazine empty, and barrel hot."

July 8th, 2009, 07:26 PM	#8
Tubesock ninjette.org member Name: David Location: Chatta-vegas Join Date: May 2009 Motorcycle(s): 2009 Kawasaki Ninja 250r Posts: 69	Oh ok I get what you're saying now. __________________________________________________ "When I die I want mud on my jump boots, magazine empty, and barrel hot."

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July 8th, 2009, 04:35 PM	#2
kkim Join Date: Nov 2008 Posts: Too much.	use the stock main jets (98). Raise the needles on clip position (lower the clip) to take care of the flat spot. is your jetting completely stock now?

July 8th, 2009, 06:05 PM	#3
Tubesock ninjette.org member Name: David Location: Chatta-vegas Join Date: May 2009 Motorcycle(s): 2009 Kawasaki Ninja 250r Posts: 69	Yes it's totally stock (I'm such a slacker I haven't even shimmed the needles). But would raising the needle effect the rpm range that high? Also will #6 washers work for shimming? __________________________________________________ "When I die I want mud on my jump boots, magazine empty, and barrel hot." Last futzed with by Tubesock; July 8th, 2009 at 06:20 PM. Reason: Additional question

July 8th, 2009, 06:30 PM	#4
Wes ninjette.org member Name: Wes Location: Kingston, ON Join Date: Jul 2009 Motorcycle(s): EX250-F14 Posts: 41	If I had to guess, I'd say you're going to need to go up on main jet size, but you should try popping a couple of washers under the needles first. Use #4 washers. They're the right size and cost about a nickel each. Wes

July 8th, 2009, 07:22 PM	#6
Tubesock ninjette.org member Name: David Location: Chatta-vegas Join Date: May 2009 Motorcycle(s): 2009 Kawasaki Ninja 250r Posts: 69	As far as the main jet goes what would be a good size to try first? __________________________________________________ "When I die I want mud on my jump boots, magazine empty, and barrel hot."

July 8th, 2009, 07:24 PM	#7
kkim Join Date: Nov 2008 Posts: Too much.	keep the stock. the bike is rich on the top end as delivered. you need to fatten up the midrange, which is the needle circuit.

April 20th, 2012, 11:27 PM	#9
MysterioX ninjette.org member Name: John Location: GTA Join Date: Apr 2010 Motorcycle(s): 2009 250 Ninja Posts: 24	I have a problem of jets getting clogged. Is it the main jet I need to replace? Someone suggested getting slow jet #38 or 40 will fix the problem.

April 22nd, 2012, 09:10 AM	#12
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	Just replacing pilot jets won't necessarily do the trick. There's little passageways that are used during various throttle openings that also get clogged. You'll only have to do it once as long as you're careful to not let it sit for months without draining the carbs and stabilizing gas. I've only cleaned mine once and since it gets ridden regularly and properly winterized every winter, I've never had to clean them again since.