Dead spot in rpm's

[chikenstrips]

I have a dead spot in my rpm between 8k-10k. could this be due to to big of a main jet?

[DaBlue1]

It's not so much a dead spot. It's just may be a too rich spot depending on your riding conditions. The Stock Ninja is nice and rich in that range, so it may take a bit for the bike to get past it quickly while accelerating in 6th gear. Down shift one gear to try to get past 10k.

http://www.250rider.com/Ninja-2010-1...Ninja-250r.jpg

[chikenstrips]

so if i downed the main jetfrom a dj100 to a dj98 it would richen it up a little and feel more smooth then?

[DaBlue1]

Originally Posted by chikenstrips

so if i downed the main jetfrom a dj100 to a dj98 it would richen it up a little and feel more smooth then?

If you went down to DJ#98, it would be similar to Keihin #100s. It wouldn't be as rich. I assume you have the stock airbox and shimmed and snorkel removed?

[chikenstrips]

i have a stock airbox with a k & n filter in it snorkel is still on and needle is shimmed yes

[DaBlue1]

Take out the snorkel. You need a little more air for the fuel you are putting in.

[chikenstrips]

thanks guys snorkel fixed it right up, runs like a dream now

I'm kind of having a similar problem. My 7-8k seems a little dead and when I'm just cruising in like 3rd gear it usually is at 7-8k and the bike just seems to want to go past that rpm because when I close the throttle a little the bike seems to.. idk like sputter in the slightest like it wants more gas? I guess you could call it a soft spot.

Edit: Snorkel is pulled, carbs are shimmed with 3 washers each, danmoto exhaust installed. Gonna pull the spark plugs and see if I'm lean/rich. I believe I'm still a little lean in the fuel side, should I look into Larger main jets like @choneofakind keeps bothering me to do?

[choneofakind]

surging in the midrange under partial throttle is a sign of lean mid-range. add a 4th washer and see if that smooths out your 7-8k range

Originally Posted by choneofakind

surging in the midrange under partial throttle is a sign of lean mid-range. Add a 4th washer and see if that smooths out your 7-8k range

i shall try it master.

[DaBlue1]

Originally Posted by codestp202

I'm kind of having a similar problem. My 7-8k seems a little dead and when I'm just cruising in like 3rd gear it usually is at 7-8k and the bike just seems to want to go past that rpm because when I close the throttle a little the bike seems to.. idk like sputter in the slightest like it wants more gas? I guess you could call it a soft spot.

Edit: Snorkel is pulled, carbs are shimmed with 3 washers each, danmoto exhaust installed. Gonna pull the spark plugs and see if I'm lean/rich. I believe I'm still a little lean in the fuel side, should I look into Larger main jets like @choneofakind keeps bothering me to do?

7-8k in 3rd gear is not cruising. The bike wants to run up the rpms and change gears. Try cruising at 5-6k.

Why do you feel like the bike is lean? From the 8-10k range, the stock Ninja is rich, you just tossed in more fuel from 1/4-3/4 throttle with 3 shims. The little extra air from the missing snorkel is not going to raise the air/fuel ratio all that much. Even if you got close to 13.4:1, you would still be in an acceptable range. You may in fact be running to rich.

One thing you need to consider is that elevation temps and humidity affect carburetion, so you may not get the same performance everyday. This info can help with figuring out your carb settings. (see fig. 7 & 8 Motorcycle Carburetor Theory 101)This is also another good piece of info. Pipe Jetting If you use a correction factor based on your avg elevation and temperature you may find that

You may not necessarily need larger jets. Stock jets may be just fine in some cases. http://www.ninjette.org/forums/showthread.php?t=102408 If you use a correction factor based on your avg elevation and temperature you may find that you might need smaller jets.

[choneofakind]

Originally Posted by DaBlue1

You may not necessarily need larger jets. Stock jets may be just fine in some cases. http://www.ninjette.org/forums/showthread.php?t=102408 If you use a correction factor based on your avg elevation and temperature you may find that you might need smaller jets.

yes, but I've seen dyno charts of ninja 250's in our area that have the same intake/exhaust mods that he has (plus an aftermarket filter) and the bike needed 100 mains. Since Cody and the other bike whose dyno curve I read are both located within 15 minutes of me and ride the same roads I ride, I'd say that's a relatively fair setup to consider when jetting. His mains are likely fine though because he doesn't have the aftermarket filter.

On top of that, my bike has the same mods (albeit the pregen equivalents) and the bike definitely feels better with a main jet that is a size larger.

In stock form, the bike is rich only when at WOT because the main jets are rich and everything else is lean.

Cruising at 7-8k means partial throttle; about 1/2 throttle. Partial throttle mix is controlled by the needle height. If the bike is surging in the 1/4-3/4 throttle openings, that means the needles need to be raised.

The question is if the bike is surging or bogging. That is the determiner for if the needles need raised or lowered.

Originally Posted by choneofakind

yes, but I've seen dyno charts of ninja 250's in our area that have the same intake/exhaust mods that he has (plus an aftermarket filter) and the bike needed 100 mains. Since Cody and the other bike whose dyno curve I read are both located within 15 minutes of me and ride the same roads I ride, I'd say that's a relatively fair setup to consider when jetting. His mains are likely fine though because he doesn't have the aftermarket filter.

On top of that, my bike has the same mods (albeit the pregen equivalents) and the bike definitely feels better with a main jet that is a size larger.

In stock form, the bike is rich only when at WOT because the main jets are rich and everything else is lean.

Cruising at 7-8k means partial throttle; about 1/2 throttle. Partial throttle mix is controlled by the needle height. If the bike is surging in the 1/4-3/4 throttle openings, that means the needles need to be raised.

The question is if the bike is surging or bogging. That is the determiner for if the needles need raised or lowered.

The bike is bogging by that definition. But only slightly, so I will definitely look into 1 more washer on each. and I'll order those main jets too if I'm gonna spend the time adding another washer to the dang thing.

On a happier note, my dad just asked me what I want for my birthday. Thinkin about getting some rim tape and a mount for my cell phone to my handlebars.
Thinking about putting white into the fairings. So the bike would have a blue/black/white theme

http://www.ebay.com/itm/RIM-STRIPE-W...ht_5018wt_1218
cool or gay in blue, and if I decide to paint it partially white should I do white tape?

I always go off topic.

[chikenstrips]

order k&n filter too. it sounds like your running rich. if you add a bigger main jet you will definitely need more air to offset all the fuel

Originally Posted by chikenstrips

order k&n filter too. it sounds like your running rich. if you add a bigger main jet you will definitely need more air to offset all the fuel

What was that other brand that made air filters that where cheaper and better?

Originally Posted by choneofakind

yes, but I've seen dyno charts of ninja 250's in our area that have the same intake/exhaust mods that he has (plus an aftermarket filter) and the bike needed 100 mains. Since Cody and the other bike whose dyno curve I read are both located within 15 minutes of me and ride the same roads I ride, I'd say that's a relatively fair setup to consider when jetting. His mains are likely fine though because he doesn't have the aftermarket filter.

On top of that, my bike has the same mods (albeit the pregen equivalents) and the bike definitely feels better with a main jet that is a size larger.

In stock form, the bike is rich only when at WOT because the main jets are rich and everything else is lean.

Cruising at 7-8k means partial throttle; about 1/2 throttle. Partial throttle mix is controlled by the needle height. If the bike is surging in the 1/4-3/4 throttle openings, that means the needles need to be raised.

The question is if the bike is surging or bogging. That is the determiner for if the needles need raised or lowered.

**** dude what was the link for those jets again? I thought I bookmarked it but I guess I lost it

[choneofakind]

It's bogging in that range? then take a washer off the needles to lower them again.
bogging = rich.
surging unevenly instead of cruising smoothly = lean.

http://jetsrus.com/a_jet_kit_street/...50R_Ninja.html

You might find the 98's pull better than the 100's but the 100's are worth the test, considering they're only $6.00 and one day of work on the bike.

Always make only one change at a time to the carbs to pinpoint what changes had what affect on how the bike feels.

Originally Posted by choneofakind

It's bogging in that range? then take a washer off the needles to lower them again.
bogging = rich.
surging unevenly instead of cruising smoothly = lean.

http://jetsrus.com/a_jet_kit_street/...50R_Ninja.html

You might find the 98's pull better than the 100's but the 100's are worth the test, considering they're only $6.00 and one day of work on the bike.

Always make only one change at a time to the carbs to pinpoint what changes had what affect on how the bike feels.

**** Idk if if bogging would be the right thing to call it lol. Maybe I'll just take a vid when I get home.

[choneofakind]

Vid won't do much. Put the snorkel on. Does it get better or worse in that range/that exact scenario?

LOL I kinda partially destroyed the snorkel I'm gonna put the air filter in, add a new main jet, and see how it acts with that. Then I will see if I need to add or remove a washer

[choneofakind]

gaahhh!!! 1 change at a time grasshoppa!!!!

I dont roll like that. I don't know if I'm really thinking right when I say its acting wierd in the 7-8k range. For instance, I cruise at like 40 in 3rd gear at like 7-8k, should I just shift up so it rides at like 6k?

[choneofakind]

up to you. The bike is fine either way, just maybe a bit noisy if you keep it at 8000

Originally Posted by choneofakind

up to you. The bike is fine either way, just maybe a bit noisy if you keep it at 8000

So... wanna put that ninja 400 engine in my bike for me?

[DaBlue1]

Originally Posted by codestp202

What was that other brand that made air filters that where cheaper and better?

Pipercross? UNI?
http://www.ninjette.org/wiki/Air_filters_for_newgens

Originally Posted by DaBlue1

Pipercross? UNI?
http://www.ninjette.org/wiki/Air_filters_for_newgens

Good call! Pipecross! Even checked the wiki dunno why I didnt see it..