To jet or not to jet, that is the question.

WoRMinator · November 9th, 2010, 01:58 PM

Let me star by saying hello to everyone on this informative site! I just purchased a 2010 250 about a month ago. So far I love it. I bought this bike because I like the sport bike look but have no need for the speed of a super sport. I just installed a PLMFG exhaust and have been reading peoples thoughts on jetting with a full exhaust. I have not done anything else to the bike yet. I plan on getting a k&n air filter.
The reason for this post is that I'm trying to figure out if I should jet carburetors. I planned on having my carburetors jetted at the dealership that sold me the bike. I just got off the phone with their service dept and they basically told me that it i do not need to jet it. I mentioned to them about what I've been reading on the forums about the bike being naturally lean and that it should be even more with the full exhaust upgrade. The fellow there said that he can richen things up by just adjusting the pilots without a need to jet.
Does any of this make sense?

HKr1 · November 9th, 2010, 02:28 PM

I would find another shop. The adjustment he is speaking of is only for the idle mixture.

g21-30 · November 9th, 2010, 02:33 PM

You either need to shim (use washers) your needles or buy a DynoJet kit and use the needles/shims only from it (install per the instructions), set your idle mixture screws to 2.5 turns out, and remove the snorkel. That's all I did and I have the PLMFG setup. Good Luck!

The OEm .098 jets are actually rich, even for a full exhaust setup.

JMcDonald · November 9th, 2010, 02:49 PM

"Jetting" the bike richens (relative to factory specs) the entire mixture from the top down. Tuning the idle mixture screws will really just get you perhaps a crisper idle and a little better response off the line. But it wont fix anything else. Shimming the needles (which they probably wouldnt do...) would give you some more, but it wont cover you at WOT very much.

Increasing flow is about getting more air in order to be able to burn more fuel. Without more fuel, you will really dont get a lot more than a louder bike.

I would do it yourself. I was timid at first about it but the DIYs are extremely informative and now I am much more confident about my upcoming projects.
Posted via Mobile Device

WoRMinator · November 9th, 2010, 06:16 PM

hmm, beginning to wonder if i should just do this myself. He was going to charge me around 400-500 to rejet or 140 just to drill and adjust the pilot holes?! wow..

JMcDonald · November 9th, 2010, 07:14 PM

I would do it yourself. Not only is that a large amount of cash, but with that attitude and apparently low level of knowledge (for a Kawi mechanic willing to charge for the service...) I wouldn't trust they would do it correctly or at least completely (might just slap in which ever jet they grab first, make sure it runs, and call it good).

In the DIYs (if you haven't read them) are many instructionals on not only how to install and tune a full jet kit, but even to drill and adjust the idle mixture screws (which turns out to be relatively easy).

ithaca00 · November 9th, 2010, 10:51 PM

Were you going to be getting a K&N pod filter or drop-in? If just a drop-in, take a look at the filter and jet kit from Sportisi. Both are good products that I have on my bike.

WoRMinator · November 10th, 2010, 06:10 PM

i was just planning on throwing a k&n filter in the stock box. I really dont plan on modifying to much of the stock setup. Just exhaust, air filter and adjust carbs to handle the exhaust and filter.

JMcDonald · November 11th, 2010, 08:38 PM

I checked my valve lash today, and while I had the bike half-apart anyways, I went ahead and finished off with putting the K&N pod filter in. It is so lean it won't rev above about 6500 RPM, and anything beyond maybe 1/4 throttle just results in massive stuttering an hesitation.

I'm going to install my Factory Pro jet kit tomorrow, though.

Unless your bike was actually tested and found to be extremely rich from the factory, I can't imagine it running nearly as well as it could with substantial flow-increasing mods--and that's if it will even run acceptably-well at all!

November 9th, 2010, 01:58 PM	#1
WoRMinator ninjette.org newbie Name: Kenneth Location: League City Join Date: Oct 2010 Motorcycle(s): 2010 Ninja 250r Posts: 5	To jet or not to jet, that is the question. Let me star by saying hello to everyone on this informative site! I just purchased a 2010 250 about a month ago. So far I love it. I bought this bike because I like the sport bike look but have no need for the speed of a super sport. I just installed a PLMFG exhaust and have been reading peoples thoughts on jetting with a full exhaust. I have not done anything else to the bike yet. I plan on getting a k&n air filter. The reason for this post is that I'm trying to figure out if I should jet carburetors. I planned on having my carburetors jetted at the dealership that sold me the bike. I just got off the phone with their service dept and they basically told me that it i do not need to jet it. I mentioned to them about what I've been reading on the forums about the bike being naturally lean and that it should be even more with the full exhaust upgrade. The fellow there said that he can richen things up by just adjusting the pilots without a need to jet. Does any of this make sense?

November 9th, 2010, 07:14 PM	#6
JMcDonald ninjette.org sage Name: J Location: Oklahoma Join Date: Sep 2010 Motorcycle(s): 2008 250R Posts: 771	I would do it yourself. Not only is that a large amount of cash, but with that attitude and apparently low level of knowledge (for a Kawi mechanic willing to charge for the service...) I wouldn't trust they would do it correctly or at least completely (might just slap in which ever jet they grab first, make sure it runs, and call it good). In the DIYs (if you haven't read them) are many instructionals on not only how to install and tune a full jet kit, but even to drill and adjust the idle mixture screws (which turns out to be relatively easy). __________________________________________________ Factory Pro Jet Kit, K&N R-0990 Pod Filter, Sportisi VR Black Exhaust, BRT TIS Ignition, White Paint, and 16/41 Sprockets. Soon: Maybe a 37T Rear Sprocket if I get things running like I'd hoped.

November 11th, 2010, 08:38 PM	#9
JMcDonald ninjette.org sage Name: J Location: Oklahoma Join Date: Sep 2010 Motorcycle(s): 2008 250R Posts: 771	I checked my valve lash today, and while I had the bike half-apart anyways, I went ahead and finished off with putting the K&N pod filter in. It is so lean it won't rev above about 6500 RPM, and anything beyond maybe 1/4 throttle just results in massive stuttering an hesitation. I'm going to install my Factory Pro jet kit tomorrow, though. Unless your bike was actually tested and found to be extremely rich from the factory, I can't imagine it running nearly as well as it could with substantial flow-increasing mods--and that's if it will even run acceptably-well at all! __________________________________________________ Factory Pro Jet Kit, K&N R-0990 Pod Filter, Sportisi VR Black Exhaust, BRT TIS Ignition, White Paint, and 16/41 Sprockets. Soon: Maybe a 37T Rear Sprocket if I get things running like I'd hoped.

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November 9th, 2010, 02:28 PM	#2
HKr1 IC2(SW) Name: Kerry Location: Pensacola Join Date: Nov 2008 Motorcycle(s): . Posts: A lot.	I would find another shop. The adjustment he is speaking of is only for the idle mixture.

November 9th, 2010, 02:33 PM	#3
g21-30 ninjette.org certified postwhore Name: Sam Location: Northern Virginia Join Date: Nov 2008 Motorcycle(s): Ninja 250R 2009 Posts: A lot.	You either need to shim (use washers) your needles or buy a DynoJet kit and use the needles/shims only from it (install per the instructions), set your idle mixture screws to 2.5 turns out, and remove the snorkel. That's all I did and I have the PLMFG setup. Good Luck! The OEm .098 jets are actually rich, even for a full exhaust setup.

November 9th, 2010, 02:49 PM	#4
JMcDonald ninjette.org sage Name: J Location: Oklahoma Join Date: Sep 2010 Motorcycle(s): 2008 250R Posts: 771	"Jetting" the bike richens (relative to factory specs) the entire mixture from the top down. Tuning the idle mixture screws will really just get you perhaps a crisper idle and a little better response off the line. But it wont fix anything else. Shimming the needles (which they probably wouldnt do...) would give you some more, but it wont cover you at WOT very much. Increasing flow is about getting more air in order to be able to burn more fuel. Without more fuel, you will really dont get a lot more than a louder bike. I would do it yourself. I was timid at first about it but the DIYs are extremely informative and now I am much more confident about my upcoming projects. Posted via Mobile Device

November 9th, 2010, 06:16 PM	#5
WoRMinator ninjette.org newbie Name: Kenneth Location: League City Join Date: Oct 2010 Motorcycle(s): 2010 Ninja 250r Posts: 5	hmm, beginning to wonder if i should just do this myself. He was going to charge me around 400-500 to rejet or 140 just to drill and adjust the pilot holes?! wow..

November 9th, 2010, 10:51 PM	#7
ithaca00 ninjette.org guru Name: Ryan Location: Sacramento, CA Join Date: May 2009 Motorcycle(s): 2007 EX250 (street), 1994 EX250 (Race), 2008 250R (Race), 2000 250 (project), 1991 EL250 (a cruiser!) Posts: 287	Were you going to be getting a K&N pod filter or drop-in? If just a drop-in, take a look at the filter and jet kit from Sportisi. Both are good products that I have on my bike.

November 10th, 2010, 06:10 PM	#8
WoRMinator ninjette.org newbie Name: Kenneth Location: League City Join Date: Oct 2010 Motorcycle(s): 2010 Ninja 250r Posts: 5	i was just planning on throwing a k&n filter in the stock box. I really dont plan on modifying to much of the stock setup. Just exhaust, air filter and adjust carbs to handle the exhaust and filter.